Migrate httpd classes to Flogger

This is the first part of the migration to Flogger. This change migrates all classes of the 'http' module to Flogger. Other modules continue to use slf4j. They should be migrated by follow-up changes. During this migration we try to make the log statements more consistent: - avoid string concatenation - avoid usage of String.format(...) Change-Id: I473c41733b00aa1ceab92fe0dc8cd1c6b347174c Signed-off-by: Edwin Kempin <ekempin@google.com>
2018-04-30 16:29:35 +02:00
parent 2b81d71374
commit 03d2d209b1
32 changed files with 245 additions and 268 deletions
--- a/java/com/google/gerrit/httpd/BUILD
+++ b/java/com/google/gerrit/httpd/BUILD
@@ -33,11 +33,11 @@ java_library(
        "//lib/auto:auto-value-annotations",
        "//lib/commons:codec",
        "//lib/commons:lang",
+        "//lib/flogger:api",
        "//lib/guice",
        "//lib/guice:guice-assistedinject",
        "//lib/guice:guice-servlet",
        "//lib/jgit/org.eclipse.jgit.http.server:jgit-servlet",
        "//lib/jgit/org.eclipse.jgit:jgit",
-        "//lib/log:api",
    ],
 )
--- a/java/com/google/gerrit/httpd/DirectChangeByCommit.java
+++ b/java/com/google/gerrit/httpd/DirectChangeByCommit.java
@@ -4,6 +4,7 @@ package com.google.gerrit.httpd;

 import com.google.common.base.CharMatcher;
 import com.google.common.collect.ImmutableList;
+import com.google.common.flogger.FluentLogger;
 import com.google.gerrit.common.PageLinks;
 import com.google.gerrit.extensions.api.changes.Changes;
 import com.google.gerrit.extensions.common.ChangeInfo;
@@ -17,13 +18,12 @@ import java.util.List;
 import javax.servlet.http.HttpServlet;
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;

@Singleton
 class DirectChangeByCommit extends HttpServlet {
  private static final long serialVersionUID = 1L;
-  private static final Logger log = LoggerFactory.getLogger(DirectChangeByCommit.class);
+
+  private static final FluentLogger logger = FluentLogger.forEnclosingClass();

  private final Changes changes;

@@ -39,7 +39,7 @@ class DirectChangeByCommit extends HttpServlet {
    try {
      results = changes.query(query).withLimit(2).get();
    } catch (RestApiException e) {
-      log.warn("Cannot process query by URL: /r/" + query, e);
+      logger.atWarning().withCause(e).log("Cannot process query by URL: /r/%s", query);
      results = ImmutableList.of();
    }
    String token;
--- a/java/com/google/gerrit/httpd/HttpServletResponseRecorder.java
+++ b/java/com/google/gerrit/httpd/HttpServletResponseRecorder.java
@@ -14,13 +14,12 @@

 package com.google.gerrit.httpd;

+import com.google.common.flogger.FluentLogger;
 import java.io.IOException;
 import java.util.HashMap;
 import java.util.Map;
 import javax.servlet.http.HttpServletResponse;
 import javax.servlet.http.HttpServletResponseWrapper;
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;

 /**
 * HttpServletResponse wrapper to allow response status code override.
@@ -29,7 +28,7 @@ import org.slf4j.LoggerFactory;
 * override the response http status code.
 */
 public class HttpServletResponseRecorder extends HttpServletResponseWrapper {
-  private static final Logger log = LoggerFactory.getLogger(HttpServletResponseRecorder.class);
+  private static final FluentLogger logger = FluentLogger.forEnclosingClass();
  private static final String LOCATION_HEADER = "Location";

  private int status;
@@ -78,7 +77,7 @@ public class HttpServletResponseRecorder extends HttpServletResponseWrapper {

  void play() throws IOException {
    if (status != 0) {
-      log.debug("Replaying {} {}", status, statusMsg);
+      logger.atFine().log("Replaying %s %s", status, statusMsg);

      if (status == SC_MOVED_TEMPORARILY) {
        super.sendRedirect(headers.get(LOCATION_HEADER));
--- a/java/com/google/gerrit/httpd/ProjectBasicAuthFilter.java
+++ b/java/com/google/gerrit/httpd/ProjectBasicAuthFilter.java
@@ -19,6 +19,7 @@ import static javax.servlet.http.HttpServletResponse.SC_UNAUTHORIZED;

 import com.google.common.base.MoreObjects;
 import com.google.common.base.Strings;
+import com.google.common.flogger.FluentLogger;
 import com.google.gerrit.extensions.client.GitBasicAuthPolicy;
 import com.google.gerrit.extensions.registration.DynamicItem;
 import com.google.gerrit.reviewdb.client.Account;
@@ -47,8 +48,6 @@ import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
 import javax.servlet.http.HttpServletResponseWrapper;
 import org.apache.commons.codec.binary.Base64;
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;

 /**
 * Authenticates the current user by HTTP basic authentication.
@@ -62,7 +61,7 @@ import org.slf4j.LoggerFactory;
 */
@Singleton
 class ProjectBasicAuthFilter implements Filter {
-  private static final Logger log = LoggerFactory.getLogger(ProjectBasicAuthFilter.class);
+  private static final FluentLogger logger = FluentLogger.forEnclosingClass();

  public static final String REALM_NAME = "Gerrit Code Review";
  private static final String AUTHORIZATION = "Authorization";
@@ -131,10 +130,11 @@ class ProjectBasicAuthFilter implements Filter {
    Optional<AccountState> accountState =
        accountCache.getByUsername(username).filter(a -> a.getAccount().isActive());
    if (!accountState.isPresent()) {
-      log.warn(
-          "Authentication failed for "
-              + username
-              + ": account inactive or not provisioned in Gerrit");
+      logger
+          .atWarning()
+          .log(
+              "Authentication failed for %s: account inactive or not provisioned in Gerrit",
+              username);
      rsp.sendError(SC_UNAUTHORIZED);
      return false;
    }
@@ -163,17 +163,17 @@ class ProjectBasicAuthFilter implements Filter {
      if (who.checkPassword(password, username)) {
        return succeedAuthentication(who);
      }
-      log.warn(authenticationFailedMsg(username, req), e);
+      logger.atWarning().withCause(e).log(authenticationFailedMsg(username, req));
      rsp.sendError(SC_UNAUTHORIZED);
      return false;
    } catch (AuthenticationFailedException e) {
      // This exception is thrown if the user provided wrong credentials, we don't need to log a
      // stacktrace for it.
-      log.warn(authenticationFailedMsg(username, req) + ": " + e.getMessage());
+      logger.atWarning().log(authenticationFailedMsg(username, req) + ": %s", e.getMessage());
      rsp.sendError(SC_UNAUTHORIZED);
      return false;
    } catch (AccountException e) {
-      log.warn(authenticationFailedMsg(username, req), e);
+      logger.atWarning().withCause(e).log(authenticationFailedMsg(username, req));
      rsp.sendError(SC_UNAUTHORIZED);
      return false;
    }
@@ -186,10 +186,11 @@ class ProjectBasicAuthFilter implements Filter {

  private boolean failAuthentication(Response rsp, String username, HttpServletRequest req)
      throws IOException {
-    log.warn(
-        authenticationFailedMsg(username, req)
-            + ": password does not match the one stored in Gerrit",
-        username);
+    logger
+        .atWarning()
+        .log(
+            authenticationFailedMsg(username, req)
+                + ": password does not match the one stored in Gerrit");
    rsp.sendError(SC_UNAUTHORIZED);
    return false;
  }
--- a/java/com/google/gerrit/httpd/ProjectOAuthFilter.java
+++ b/java/com/google/gerrit/httpd/ProjectOAuthFilter.java
@@ -21,6 +21,7 @@ import static javax.servlet.http.HttpServletResponse.SC_UNAUTHORIZED;
 import com.google.common.base.MoreObjects;
 import com.google.common.base.Strings;
 import com.google.common.collect.Iterables;
+import com.google.common.flogger.FluentLogger;
 import com.google.gerrit.extensions.auth.oauth.OAuthLoginProvider;
 import com.google.gerrit.extensions.registration.DynamicItem;
 import com.google.gerrit.extensions.registration.DynamicMap;
@@ -54,8 +55,6 @@ import javax.servlet.http.HttpServletResponse;
 import javax.servlet.http.HttpServletResponseWrapper;
 import org.apache.commons.codec.binary.Base64;
 import org.eclipse.jgit.lib.Config;
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;

 /**
 * Authenticates the current user with an OAuth2 server.
@@ -64,8 +63,7 @@ import org.slf4j.LoggerFactory;
 */
@Singleton
 class ProjectOAuthFilter implements Filter {
-
-  private static final Logger log = LoggerFactory.getLogger(ProjectOAuthFilter.class);
+  private static final FluentLogger logger = FluentLogger.forEnclosingClass();

  private static final String REALM_NAME = "Gerrit Code Review";
  private static final String AUTHORIZATION = "Authorization";
@@ -156,9 +154,11 @@ class ProjectOAuthFilter implements Filter {
    Optional<AccountState> who =
        accountCache.getByUsername(authInfo.username).filter(a -> a.getAccount().isActive());
    if (!who.isPresent()) {
-      log.warn(
-          authenticationFailedMsg(authInfo.username, req)
-              + ": account inactive or not provisioned in Gerrit");
+      logger
+          .atWarning()
+          .log(
+              authenticationFailedMsg(authInfo.username, req)
+                  + ": account inactive or not provisioned in Gerrit");
      rsp.sendError(SC_UNAUTHORIZED);
      return false;
    }
@@ -179,7 +179,7 @@ class ProjectOAuthFilter implements Filter {
      ws.setAccessPathOk(AccessPath.REST_API, true);
      return true;
    } catch (AccountException e) {
-      log.warn(authenticationFailedMsg(authInfo.username, req), e);
+      logger.atWarning().withCause(e).log(authenticationFailedMsg(authInfo.username, req));
      rsp.sendError(SC_UNAUTHORIZED);
      return false;
    }
--- a/java/com/google/gerrit/httpd/QueryDocumentationFilter.java
+++ b/java/com/google/gerrit/httpd/QueryDocumentationFilter.java
@@ -16,6 +16,7 @@ package com.google.gerrit.httpd;

 import com.google.common.base.Strings;
 import com.google.common.collect.ImmutableListMultimap;
+import com.google.common.flogger.FluentLogger;
 import com.google.gerrit.httpd.restapi.RestApiServlet;
 import com.google.gerrit.server.documentation.QueryDocumentationExecutor;
 import com.google.gerrit.server.documentation.QueryDocumentationExecutor.DocQueryException;
@@ -32,12 +33,10 @@ import javax.servlet.ServletRequest;
 import javax.servlet.ServletResponse;
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;

@Singleton
 public class QueryDocumentationFilter implements Filter {
-  private final Logger log = LoggerFactory.getLogger(QueryDocumentationFilter.class);
+  private static final FluentLogger logger = FluentLogger.forEnclosingClass();

  private final QueryDocumentationExecutor searcher;

@@ -62,7 +61,7 @@ public class QueryDocumentationFilter implements Filter {
        List<DocResult> result = searcher.doQuery(request.getParameter("q"));
        RestApiServlet.replyJson(req, rsp, ImmutableListMultimap.of(), result);
      } catch (DocQueryException e) {
-        log.error("Doc search failed:", e);
+        logger.atSevere().withCause(e).log("Doc search failed");
        rsp.sendError(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
      }
    } else {
--- a/java/com/google/gerrit/httpd/RunAsFilter.java
+++ b/java/com/google/gerrit/httpd/RunAsFilter.java
@@ -18,6 +18,7 @@ import static com.google.gerrit.httpd.restapi.RestApiServlet.replyError;
 import static javax.servlet.http.HttpServletResponse.SC_FORBIDDEN;
 import static javax.servlet.http.HttpServletResponse.SC_INTERNAL_SERVER_ERROR;

+import com.google.common.flogger.FluentLogger;
 import com.google.gerrit.extensions.registration.DynamicItem;
 import com.google.gerrit.extensions.restapi.AuthException;
 import com.google.gerrit.reviewdb.client.Account;
@@ -41,13 +42,11 @@ import javax.servlet.ServletResponse;
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
 import org.eclipse.jgit.errors.ConfigInvalidException;
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;

 /** Allows running a request as another user account. */
@Singleton
 class RunAsFilter implements Filter {
-  private static final Logger log = LoggerFactory.getLogger(RunAsFilter.class);
+  private static final FluentLogger logger = FluentLogger.forEnclosingClass();
  private static final String RUN_AS = "X-Gerrit-RunAs";

  static class Module extends ServletModule {
@@ -99,7 +98,7 @@ class RunAsFilter implements Filter {
        replyError(req, res, SC_FORBIDDEN, "not permitted to use " + RUN_AS, null);
        return;
      } catch (PermissionBackendException e) {
-        log.warn("cannot check runAs", e);
+        logger.atWarning().withCause(e).log("cannot check runAs");
        replyError(req, res, SC_INTERNAL_SERVER_ERROR, RUN_AS + " unavailable", null);
        return;
      }
@@ -108,7 +107,7 @@ class RunAsFilter implements Filter {
      try {
        target = accountResolver.find(runas);
      } catch (OrmException | IOException | ConfigInvalidException e) {
-        log.warn("cannot resolve account for " + RUN_AS, e);
+        logger.atWarning().withCause(e).log("cannot resolve account for %s", RUN_AS);
        replyError(req, res, SC_INTERNAL_SERVER_ERROR, "cannot resolve " + RUN_AS, e);
        return;
      }
--- a/java/com/google/gerrit/httpd/WebSessionManager.java
+++ b/java/com/google/gerrit/httpd/WebSessionManager.java
@@ -29,6 +29,7 @@ import static java.util.concurrent.TimeUnit.MINUTES;
 import static java.util.concurrent.TimeUnit.SECONDS;

 import com.google.common.cache.Cache;
+import com.google.common.flogger.FluentLogger;
 import com.google.gerrit.reviewdb.client.Account;
 import com.google.gerrit.server.account.externalids.ExternalId;
 import com.google.gerrit.server.config.ConfigUtil;
@@ -43,11 +44,9 @@ import java.io.Serializable;
 import java.security.SecureRandom;
 import java.util.concurrent.TimeUnit;
 import org.eclipse.jgit.lib.Config;
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;

 public class WebSessionManager {
-  private static final Logger log = LoggerFactory.getLogger(WebSessionManager.class);
+  private static final FluentLogger logger = FluentLogger.forEnclosingClass();
  public static final String CACHE_NAME = "web_sessions";

  private final long sessionMaxAgeMillis;
@@ -69,10 +68,11 @@ public class WebSessionManager {
                SECONDS.convert(MAX_AGE_MINUTES, MINUTES),
                SECONDS));
    if (sessionMaxAgeMillis < MINUTES.toMillis(5)) {
-      log.warn(
-          String.format(
+      logger
+          .atWarning()
+          .log(
              "cache.%s.maxAge is set to %d milliseconds; it should be at least 5 minutes.",
-              CACHE_NAME, sessionMaxAgeMillis));
+              CACHE_NAME, sessionMaxAgeMillis);
    }
  }

--- a/java/com/google/gerrit/httpd/auth/container/HttpLoginServlet.java
+++ b/java/com/google/gerrit/httpd/auth/container/HttpLoginServlet.java
@@ -17,6 +17,7 @@ package com.google.gerrit.httpd.auth.container;
 import static com.google.gerrit.server.account.externalids.ExternalId.SCHEME_EXTERNAL;
 import static java.nio.charset.StandardCharsets.UTF_8;

+import com.google.common.flogger.FluentLogger;
 import com.google.gerrit.common.PageLinks;
 import com.google.gerrit.extensions.registration.DynamicItem;
 import com.google.gerrit.httpd.CanonicalWebUrl;
@@ -40,8 +41,6 @@ import javax.servlet.http.HttpServlet;
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
 import org.eclipse.jgit.errors.ConfigInvalidException;
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
 import org.w3c.dom.Document;
 import org.w3c.dom.Element;
 import org.w3c.dom.Node;
@@ -56,7 +55,7 @@ import org.w3c.dom.NodeList;
@Singleton
 class HttpLoginServlet extends HttpServlet {
  private static final long serialVersionUID = 1L;
-  private static final Logger log = LoggerFactory.getLogger(HttpLoginServlet.class);
+  private static final FluentLogger logger = FluentLogger.forEnclosingClass();

  private final DynamicItem<WebSession> webSession;
  private final CanonicalWebUrl urlProvider;
@@ -86,10 +85,12 @@ class HttpLoginServlet extends HttpServlet {
    CacheHeaders.setNotCacheable(rsp);
    final String user = authFilter.getRemoteUser(req);
    if (user == null || "".equals(user)) {
-      log.error(
-          "Unable to authenticate user by "
-              + authFilter.getLoginHeader()
-              + " request header.  Check container or server configuration.");
+      logger
+          .atSevere()
+          .log(
+              "Unable to authenticate user by %s request header."
+                  + " Check container or server configuration.",
+              authFilter.getLoginHeader());

      final Document doc =
          HtmlDomUtil.parseFile( //
@@ -118,7 +119,7 @@ class HttpLoginServlet extends HttpServlet {
    try {
      arsp = accountManager.authenticate(areq);
    } catch (AccountException e) {
-      log.error("Unable to authenticate user \"" + user + "\"", e);
+      logger.atSevere().withCause(e).log("Unable to authenticate user \"%s\"", user);
      rsp.sendError(HttpServletResponse.SC_FORBIDDEN);
      return;
    }
@@ -126,16 +127,17 @@ class HttpLoginServlet extends HttpServlet {
    String remoteExternalId = authFilter.getRemoteExternalIdToken(req);
    if (remoteExternalId != null) {
      try {
-        log.debug("Associating external identity \"{}\" to user \"{}\"", remoteExternalId, user);
+        logger
+            .atFine()
+            .log("Associating external identity \"%s\" to user \"%s\"", remoteExternalId, user);
        updateRemoteExternalId(arsp, remoteExternalId);
      } catch (AccountException | OrmException | ConfigInvalidException e) {
-        log.error(
-            "Unable to associate external identity \""
-                + remoteExternalId
-                + "\" to user \""
-                + user
-                + "\"",
-            e);
+        logger
+            .atSevere()
+            .withCause(e)
+            .log(
+                "Unable to associate external identity \"%s\" to user \"%s\"",
+                remoteExternalId, user);
        rsp.sendError(HttpServletResponse.SC_FORBIDDEN);
        return;
      }
--- a/java/com/google/gerrit/httpd/auth/container/HttpsClientSslCertAuthFilter.java
+++ b/java/com/google/gerrit/httpd/auth/container/HttpsClientSslCertAuthFilter.java
@@ -14,6 +14,7 @@

 package com.google.gerrit.httpd.auth.container;

+import com.google.common.flogger.FluentLogger;
 import com.google.gerrit.extensions.registration.DynamicItem;
 import com.google.gerrit.httpd.WebSession;
 import com.google.gerrit.server.account.AccountException;
@@ -32,14 +33,12 @@ import javax.servlet.FilterConfig;
 import javax.servlet.ServletException;
 import javax.servlet.ServletRequest;
 import javax.servlet.ServletResponse;
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;

@Singleton
 class HttpsClientSslCertAuthFilter implements Filter {
+  private static final FluentLogger logger = FluentLogger.forEnclosingClass();

  private static final Pattern REGEX_USERID = Pattern.compile("CN=([^,]*)");
-  private static final Logger log = LoggerFactory.getLogger(HttpsClientSslCertAuthFilter.class);

  private final DynamicItem<WebSession> webSession;
  private final AccountManager accountManager;
@@ -77,7 +76,7 @@ class HttpsClientSslCertAuthFilter implements Filter {
      arsp = accountManager.authenticate(areq);
    } catch (AccountException e) {
      String err = "Unable to authenticate user \"" + userName + "\"";
-      log.error(err, e);
+      logger.atSevere().withCause(e).log(err);
      throw new ServletException(err, e);
    }
    webSession.get().login(arsp, true);
--- a/java/com/google/gerrit/httpd/auth/ldap/LdapLoginServlet.java
+++ b/java/com/google/gerrit/httpd/auth/ldap/LdapLoginServlet.java
@@ -18,6 +18,7 @@ import static java.nio.charset.StandardCharsets.UTF_8;

 import com.google.common.base.MoreObjects;
 import com.google.common.base.Strings;
+import com.google.common.flogger.FluentLogger;
 import com.google.gerrit.common.Nullable;
 import com.google.gerrit.extensions.registration.DynamicItem;
 import com.google.gerrit.httpd.CanonicalWebUrl;
@@ -41,8 +42,6 @@ import javax.servlet.ServletOutputStream;
 import javax.servlet.http.HttpServlet;
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
 import org.w3c.dom.Document;
 import org.w3c.dom.Element;

@@ -50,7 +49,7 @@ import org.w3c.dom.Element;
@SuppressWarnings("serial")
@Singleton
 class LdapLoginServlet extends HttpServlet {
-  private static final Logger log = LoggerFactory.getLogger(LdapLoginServlet.class);
+  private static final FluentLogger logger = FluentLogger.forEnclosingClass();

  private final AccountManager accountManager;
  private final DynamicItem<WebSession> webSession;
@@ -130,15 +129,15 @@ class LdapLoginServlet extends HttpServlet {
    } catch (AuthenticationFailedException e) {
      // This exception is thrown if the user provided wrong credentials, we don't need to log a
      // stacktrace for it.
-      log.warn("'{}' failed to sign in: {}", username, e.getMessage());
+      logger.atWarning().log("'%s' failed to sign in: %s", username, e.getMessage());
      sendForm(req, res, "Invalid username or password.");
      return;
    } catch (AccountException e) {
-      log.warn("'{}' failed to sign in", username, e);
+      logger.atWarning().withCause(e).log("'%s' failed to sign in", username);
      sendForm(req, res, "Authentication failed.");
      return;
    } catch (RuntimeException e) {
-      log.error("LDAP authentication failed", e);
+      logger.atSevere().withCause(e).log("LDAP authentication failed");
      sendForm(req, res, "Authentication unavailable at this time.");
      return;
    }
--- a/java/com/google/gerrit/httpd/auth/oauth/BUILD
+++ b/java/com/google/gerrit/httpd/auth/oauth/BUILD
@@ -15,9 +15,9 @@ java_library(
        "//lib:gwtorm",
        "//lib:servlet-api-3_1",
        "//lib/commons:codec",
+        "//lib/flogger:api",
        "//lib/guice",
        "//lib/guice:guice-servlet",
        "//lib/jgit/org.eclipse.jgit:jgit",
-        "//lib/log:api",
    ],
 )
--- a/java/com/google/gerrit/httpd/auth/oauth/OAuthSession.java
+++ b/java/com/google/gerrit/httpd/auth/oauth/OAuthSession.java
@@ -18,6 +18,7 @@ import static javax.servlet.http.HttpServletResponse.SC_UNAUTHORIZED;

 import com.google.common.base.CharMatcher;
 import com.google.common.base.Strings;
+import com.google.common.flogger.FluentLogger;
 import com.google.gerrit.extensions.auth.oauth.OAuthServiceProvider;
 import com.google.gerrit.extensions.auth.oauth.OAuthToken;
 import com.google.gerrit.extensions.auth.oauth.OAuthUserInfo;
@@ -47,13 +48,12 @@ import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
 import org.apache.commons.codec.binary.Base64;
 import org.eclipse.jgit.errors.ConfigInvalidException;
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;

@SessionScoped
 /* OAuth protocol implementation */
 class OAuthSession {
-  private static final Logger log = LoggerFactory.getLogger(OAuthSession.class);
+  private static final FluentLogger logger = FluentLogger.forEnclosingClass();
+
  private static final SecureRandom randomState = newRandomGenerator();
  private final String state;
  private final DynamicItem<WebSession> webSession;
@@ -93,7 +93,7 @@ class OAuthSession {
  boolean login(
      HttpServletRequest request, HttpServletResponse response, OAuthServiceProvider oauth)
      throws IOException {
-    log.debug("Login " + this);
+    logger.atFine().log("Login %s", this);

    if (isOAuthFinal(request)) {
      if (!checkState(request)) {
@@ -101,19 +101,19 @@ class OAuthSession {
        return false;
      }

-      log.debug("Login-Retrieve-User " + this);
+      logger.atFine().log("Login-Retrieve-User %s", this);
      OAuthToken token = oauth.getAccessToken(new OAuthVerifier(request.getParameter("code")));
      user = oauth.getUserInfo(token);

      if (isLoggedIn()) {
-        log.debug("Login-SUCCESS " + this);
+        logger.atFine().log("Login-SUCCESS %s", this);
        authenticateAndRedirect(request, response, token);
        return true;
      }
      response.sendError(SC_UNAUTHORIZED);
      return false;
    }
-    log.debug("Login-PHASE1 " + this);
+    logger.atFine().log("Login-PHASE1 %s", this);
    redirectToken = request.getRequestURI();
    // We are here in content of filter.
    // Due to this Jetty limitation:
@@ -148,7 +148,7 @@ class OAuthSession {
      accountId = arsp.getAccountId();
      tokenCache.put(accountId, token);
    } catch (AccountException e) {
-      log.error("Unable to authenticate user \"" + user + "\"", e);
+      logger.atSevere().withCause(e).log("Unable to authenticate user \"%s\"", user);
      rsp.sendError(HttpServletResponse.SC_FORBIDDEN);
      return;
    }
@@ -169,40 +169,33 @@ class OAuthSession {
    if (claimedId.isPresent() && actualId.isPresent()) {
      if (claimedId.get().equals(actualId.get())) {
        // Both link to the same account, that's what we expected.
-        log.debug("OAuth2: claimed identity equals current id");
+        logger.atFine().log("OAuth2: claimed identity equals current id");
      } else {
        // This is (for now) a fatal error. There are two records
        // for what might be the same user.
        //
-        log.error(
-            "OAuth accounts disagree over user identity:\n"
-                + "  Claimed ID: "
-                + claimedId.get()
-                + " is "
-                + claimedIdentifier
-                + "\n"
-                + "  Delgate ID: "
-                + actualId.get()
-                + " is "
-                + user.getExternalId());
+        logger
+            .atSevere()
+            .log(
+                "OAuth accounts disagree over user identity:\n"
+                    + "  Claimed ID: %s is %s\n"
+                    + "  Delgate ID: %s is %s",
+                claimedId.get(), claimedIdentifier, actualId.get(), user.getExternalId());
        rsp.sendError(HttpServletResponse.SC_FORBIDDEN);
        return false;
      }
    } else if (claimedId.isPresent() && !actualId.isPresent()) {
      // Claimed account already exists: link to it.
      //
-      log.info("OAuth2: linking claimed identity to {}", claimedId.get().toString());
+      logger.atInfo().log("OAuth2: linking claimed identity to %s", claimedId.get().toString());
      try {
        accountManager.link(claimedId.get(), req);
      } catch (OrmException | ConfigInvalidException e) {
-        log.error(
-            "Cannot link: "
-                + user.getExternalId()
-                + " to user identity:\n"
-                + "  Claimed ID: "
-                + claimedId.get()
-                + " is "
-                + claimedIdentifier);
+        logger
+            .atSevere()
+            .log(
+                "Cannot link: %s to user identity:\n  Claimed ID: %s is %s",
+                user.getExternalId(), claimedId.get(), claimedIdentifier);
        rsp.sendError(HttpServletResponse.SC_FORBIDDEN);
        return false;
      }
@@ -215,11 +208,11 @@ class OAuthSession {
    try {
      accountManager.link(identifiedUser.get().getAccountId(), areq);
    } catch (OrmException | ConfigInvalidException e) {
-      log.error(
-          "Cannot link: "
-              + user.getExternalId()
-              + " to user identity: "
-              + identifiedUser.get().getAccountId());
+      logger
+          .atSevere()
+          .log(
+              "Cannot link: %s to user identity: %s",
+              user.getExternalId(), identifiedUser.get().getAccountId());
      rsp.sendError(HttpServletResponse.SC_FORBIDDEN);
      return false;
    } finally {
@@ -241,7 +234,7 @@ class OAuthSession {
  private boolean checkState(ServletRequest request) {
    String s = Strings.nullToEmpty(request.getParameter("state"));
    if (!s.equals(state)) {
-      log.error("Illegal request state '" + s + "' on OAuthProtocol " + this);
+      logger.atSevere().log("Illegal request state '%s' on OAuthProtocol %s", s, this);
      return false;
    }
    return true;
--- a/java/com/google/gerrit/httpd/auth/openid/BUILD
+++ b/java/com/google/gerrit/httpd/auth/openid/BUILD
@@ -17,10 +17,10 @@ java_library(
        "//lib:gwtorm",
        "//lib:servlet-api-3_1",
        "//lib/commons:codec",
+        "//lib/flogger:api",
        "//lib/guice",
        "//lib/guice:guice-servlet",
        "//lib/jgit/org.eclipse.jgit:jgit",
-        "//lib/log:api",
        "//lib/openid:consumer",
    ],
 )
--- a/java/com/google/gerrit/httpd/auth/openid/LoginForm.java
+++ b/java/com/google/gerrit/httpd/auth/openid/LoginForm.java
@@ -20,6 +20,7 @@ import com.google.common.base.MoreObjects;
 import com.google.common.base.Strings;
 import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.ImmutableSet;
+import com.google.common.flogger.FluentLogger;
 import com.google.gerrit.common.Nullable;
 import com.google.gerrit.common.PageLinks;
 import com.google.gerrit.common.auth.openid.OpenIdUrls;
@@ -47,8 +48,6 @@ import javax.servlet.http.HttpServlet;
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
 import org.eclipse.jgit.lib.Config;
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
 import org.w3c.dom.Document;
 import org.w3c.dom.Element;

@@ -56,7 +55,8 @@ import org.w3c.dom.Element;
@SuppressWarnings("serial")
@Singleton
 class LoginForm extends HttpServlet {
-  private static final Logger log = LoggerFactory.getLogger(LoginForm.class);
+  private static final FluentLogger logger = FluentLogger.forEnclosingClass();
+
  private static final ImmutableMap<String, String> ALL_PROVIDERS =
      ImmutableMap.of(
          "launchpad", OpenIdUrls.URL_LAUNCHPAD,
@@ -91,7 +91,7 @@ class LoginForm extends HttpServlet {
    this.oauthServiceProviders = oauthServiceProviders;

    if (urlProvider == null || Strings.isNullOrEmpty(urlProvider.get())) {
-      log.error("gerrit.canonicalWebUrl must be set in gerrit.config");
+      logger.atSevere().log("gerrit.canonicalWebUrl must be set in gerrit.config");
    }

    if (authConfig.getAuthType() == AuthType.OPENID_SSO) {
@@ -160,14 +160,14 @@ class LoginForm extends HttpServlet {
      mode = SignInMode.SIGN_IN;
    }

-    log.debug("mode \"{}\"", mode);
+    logger.atFine().log("mode \"%s\"", mode);
    OAuthServiceProvider oauthProvider = lookupOAuthServiceProvider(id);

    if (oauthProvider == null) {
-      log.debug("OpenId provider \"{}\"", id);
+      logger.atFine().log("OpenId provider \"%s\"", id);
      discover(req, res, link, id, remember, token, mode);
    } else {
-      log.debug("OAuth provider \"{}\"", id);
+      logger.atFine().log("OAuth provider \"%s\"", id);
      OAuthSessionOverOpenID oauthSession = oauthSessionProvider.get();
      if (!currentUserProvider.get().isIdentifiedUser() && oauthSession.isLoggedIn()) {
        oauthSession.logout();
--- a/java/com/google/gerrit/httpd/auth/openid/OAuthSessionOverOpenID.java
+++ b/java/com/google/gerrit/httpd/auth/openid/OAuthSessionOverOpenID.java
@@ -17,6 +17,7 @@ package com.google.gerrit.httpd.auth.openid;
 import static javax.servlet.http.HttpServletResponse.SC_UNAUTHORIZED;

 import com.google.common.base.Strings;
+import com.google.common.flogger.FluentLogger;
 import com.google.gerrit.extensions.auth.oauth.OAuthServiceProvider;
 import com.google.gerrit.extensions.auth.oauth.OAuthToken;
 import com.google.gerrit.extensions.auth.oauth.OAuthUserInfo;
@@ -45,14 +46,13 @@ import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
 import org.apache.commons.codec.binary.Base64;
 import org.eclipse.jgit.errors.ConfigInvalidException;
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;

 /** OAuth protocol implementation */
@SessionScoped
 class OAuthSessionOverOpenID {
+  private static final FluentLogger logger = FluentLogger.forEnclosingClass();
+
  static final String GERRIT_LOGIN = "/login";
-  private static final Logger log = LoggerFactory.getLogger(OAuthSessionOverOpenID.class);
  private static final SecureRandom randomState = newRandomGenerator();
  private final String state;
  private final DynamicItem<WebSession> webSession;
@@ -89,7 +89,7 @@ class OAuthSessionOverOpenID {
  boolean login(
      HttpServletRequest request, HttpServletResponse response, OAuthServiceProvider oauth)
      throws IOException {
-    log.debug("Login " + this);
+    logger.atFine().log("Login %s", this);

    if (isOAuthFinal(request)) {
      if (!checkState(request)) {
@@ -97,19 +97,19 @@ class OAuthSessionOverOpenID {
        return false;
      }

-      log.debug("Login-Retrieve-User " + this);
+      logger.atFine().log("Login-Retrieve-User %s", this);
      token = oauth.getAccessToken(new OAuthVerifier(request.getParameter("code")));
      user = oauth.getUserInfo(token);

      if (isLoggedIn()) {
-        log.debug("Login-SUCCESS " + this);
+        logger.atFine().log("Login-SUCCESS %s", this);
        authenticateAndRedirect(request, response);
        return true;
      }
      response.sendError(SC_UNAUTHORIZED);
      return false;
    }
-    log.debug("Login-PHASE1 " + this);
+    logger.atFine().log("Login-PHASE1 %s", this);
    redirectToken = LoginUrlToken.getToken(request);
    response.sendRedirect(oauth.getAuthorizationUrl() + "&state=" + state);
    return false;
@@ -135,50 +135,43 @@ class OAuthSessionOverOpenID {
      if (!Strings.isNullOrEmpty(claimedIdentifier)) {
        claimedId = accountManager.lookup(claimedIdentifier);
        if (!claimedId.isPresent()) {
-          log.debug("Claimed identity is unknown");
+          logger.atFine().log("Claimed identity is unknown");
        }
      }

      // Use case 1: claimed identity was provided during handshake phase
      // and user account exists for this identity
      if (claimedId.isPresent()) {
-        log.debug("Claimed identity is set and is known");
+        logger.atFine().log("Claimed identity is set and is known");
        if (actualId.isPresent()) {
          if (claimedId.get().equals(actualId.get())) {
            // Both link to the same account, that's what we expected.
-            log.debug("Both link to the same account. All is fine.");
+            logger.atFine().log("Both link to the same account. All is fine.");
          } else {
            // This is (for now) a fatal error. There are two records
            // for what might be the same user. The admin would have to
            // link the accounts manually.
-            log.error(
-                "OAuth accounts disagree over user identity:\n"
-                    + "  Claimed ID: "
-                    + claimedId.get()
-                    + " is "
-                    + claimedIdentifier
-                    + "\n"
-                    + "  Delgate ID: "
-                    + actualId.get()
-                    + " is "
-                    + user.getExternalId());
+            logger
+                .atFine()
+                .log(
+                    "OAuth accounts disagree over user identity:\n"
+                        + "  Claimed ID: %s is %s\n"
+                        + "  Delgate ID: %s is %s",
+                    claimedId.get(), claimedIdentifier, actualId.get(), user.getExternalId());
            rsp.sendError(HttpServletResponse.SC_FORBIDDEN);
            return;
          }
        } else {
          // Claimed account already exists: link to it.
-          log.debug("Claimed account already exists: link to it.");
+          logger.atFine().log("Claimed account already exists: link to it.");
          try {
            accountManager.link(claimedId.get(), areq);
          } catch (OrmException | ConfigInvalidException e) {
-            log.error(
-                "Cannot link: "
-                    + user.getExternalId()
-                    + " to user identity:\n"
-                    + "  Claimed ID: "
-                    + claimedId.get()
-                    + " is "
-                    + claimedIdentifier);
+            logger
+                .atSevere()
+                .log(
+                    "Cannot link: %s to user identity:\n  Claimed ID: %s is %s",
+                    user.getExternalId(), claimedId.get(), claimedIdentifier);
            rsp.sendError(HttpServletResponse.SC_FORBIDDEN);
            return;
          }
@@ -187,10 +180,12 @@ class OAuthSessionOverOpenID {
        // Use case 2: link mode activated from the UI
        Account.Id accountId = identifiedUser.get().getAccountId();
        try {
-          log.debug("Linking \"{}\" to \"{}\"", user.getExternalId(), accountId);
+          logger.atFine().log("Linking \"%s\" to \"%s\"", user.getExternalId(), accountId);
          accountManager.link(accountId, areq);
        } catch (OrmException | ConfigInvalidException e) {
-          log.error("Cannot link: " + user.getExternalId() + " to user identity: " + accountId);
+          logger
+              .atSevere()
+              .log("Cannot link: %s to user identity: %s", user.getExternalId(), accountId);
          rsp.sendError(HttpServletResponse.SC_FORBIDDEN);
          return;
        } finally {
@@ -202,7 +197,7 @@ class OAuthSessionOverOpenID {
      areq.setDisplayName(user.getDisplayName());
      arsp = accountManager.authenticate(areq);
    } catch (AccountException e) {
-      log.error("Unable to authenticate user \"" + user + "\"", e);
+      logger.atSevere().withCause(e).log("Unable to authenticate user \"%s\"", user);
      rsp.sendError(HttpServletResponse.SC_FORBIDDEN);
      return;
    }
@@ -223,7 +218,7 @@ class OAuthSessionOverOpenID {
  private boolean checkState(ServletRequest request) {
    String s = Strings.nullToEmpty(request.getParameter("state"));
    if (!s.equals(state)) {
-      log.error("Illegal request state '" + s + "' on OAuthProtocol " + this);
+      logger.atSevere().log("Illegal request state '%s' on OAuthProtocol %s", s, this);
      return false;
    }
    return true;
--- a/java/com/google/gerrit/httpd/auth/openid/OpenIdServiceImpl.java
+++ b/java/com/google/gerrit/httpd/auth/openid/OpenIdServiceImpl.java
@@ -14,6 +14,7 @@

 package com.google.gerrit.httpd.auth.openid;

+import com.google.common.flogger.FluentLogger;
 import com.google.gerrit.common.PageLinks;
 import com.google.gerrit.common.auth.openid.OpenIdUrls;
 import com.google.gerrit.extensions.registration.DynamicItem;
@@ -64,12 +65,10 @@ import org.openid4java.message.sreg.SRegMessage;
 import org.openid4java.message.sreg.SRegRequest;
 import org.openid4java.message.sreg.SRegResponse;
 import org.openid4java.util.HttpClientFactory;
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;

@Singleton
 class OpenIdServiceImpl {
-  private static final Logger log = LoggerFactory.getLogger(OpenIdServiceImpl.class);
+  private static final FluentLogger logger = FluentLogger.forEnclosingClass();

  static final String RETURN_URL = "OpenID";

@@ -151,7 +150,7 @@ class OpenIdServiceImpl {
    final AuthRequest aReq;
    try {
      aReq = manager.authenticate(state.discovered, state.retTo.toString());
-      log.debug("OpenID: openid-realm={}", state.contextUrl);
+      logger.atFine().log("OpenID: openid-realm=%s", state.contextUrl);
      aReq.setRealm(state.contextUrl);

      if (requestRegistration(aReq)) {
@@ -173,7 +172,7 @@ class OpenIdServiceImpl {
        aReq.addExtension(pape);
      }
    } catch (MessageException | ConsumerException e) {
-      log.error("Cannot create OpenID redirect for " + openidIdentifier, e);
+      logger.atSevere().withCause(e).log("Cannot create OpenID redirect for %s" + openidIdentifier);
      return new DiscoveryResult(DiscoveryResult.Status.ERROR);
    }

@@ -195,7 +194,7 @@ class OpenIdServiceImpl {
    try {
      return accountManager.lookup(aReq.getIdentity()) == null;
    } catch (AccountException e) {
-      log.warn("Cannot determine if user account exists", e);
+      logger.atWarning().withCause(e).log("Cannot determine if user account exists");
      return true;
    }
  }
@@ -250,17 +249,18 @@ class OpenIdServiceImpl {
      if ("Nonce verification failed.".equals(result.getStatusMsg())) {
        // We might be suffering from clock skew on this system.
        //
-        log.error(
-            "OpenID failure: "
-                + result.getStatusMsg()
-                + "  Likely caused by clock skew on this server,"
-                + " install/configure NTP.");
+        logger
+            .atSevere()
+            .log(
+                "OpenID failure: %s  Likely caused by clock skew on this server,"
+                    + " install/configure NTP.",
+                result.getStatusMsg());
        cancelWithError(req, rsp, result.getStatusMsg());

      } else if (result.getStatusMsg() != null) {
        // Authentication failed.
        //
-        log.error("OpenID failure: " + result.getStatusMsg());
+        logger.atSevere().log("OpenID failure: %s", result.getStatusMsg());
        cancelWithError(req, rsp, result.getStatusMsg());

      } else {
@@ -286,12 +286,12 @@ class OpenIdServiceImpl {
        // right now. Instead of blocking all of them log the error and
        // let the authentication complete anyway.
        //
-        log.error("Invalid PAPE response " + openidIdentifier + ": " + err);
+        logger.atSevere().log("Invalid PAPE response %s: %s", openidIdentifier, err);
        unsupported = true;
        ext = null;
      }
      if (!unsupported && ext == null) {
-        log.error("No PAPE extension response from " + openidIdentifier);
+        logger.atSevere().log("No PAPE extension response from %s", openidIdentifier);
        cancelWithError(req, rsp, "OpenID provider does not support PAPE.");
        return;
      }
@@ -354,7 +354,7 @@ class OpenIdServiceImpl {
        }

        if (!match) {
-          log.error("Domain disallowed: " + emailDomain);
+          logger.atSevere().log("Domain disallowed: %s", emailDomain);
          cancelWithError(req, rsp, "Domain disallowed");
          return;
        }
@@ -376,17 +376,13 @@ class OpenIdServiceImpl {
          // This is (for now) a fatal error. There are two records
          // for what might be the same user.
          //
-          log.error(
-              "OpenID accounts disagree over user identity:\n"
-                  + "  Claimed ID: "
-                  + claimedId.get()
-                  + " is "
-                  + claimedIdentifier
-                  + "\n"
-                  + "  Delgate ID: "
-                  + actualId.get()
-                  + " is "
-                  + areq.getExternalIdKey());
+          logger
+              .atSevere()
+              .log(
+                  "OpenID accounts disagree over user identity:\n"
+                      + "  Claimed ID: %s is %s\n"
+                      + "  Delgate ID: %s is %s",
+                  claimedId.get(), claimedIdentifier, actualId.get(), areq.getExternalIdKey());
          cancelWithError(req, rsp, "Contact site administrator");
          return;
        }
@@ -451,7 +447,7 @@ class OpenIdServiceImpl {
          }
      }
    } catch (AccountException e) {
-      log.error("OpenID authentication failure", e);
+      logger.atSevere().withCause(e).log("OpenID authentication failure");
      cancelWithError(req, rsp, "Contact site administrator");
    }
  }
@@ -531,7 +527,7 @@ class OpenIdServiceImpl {
    try {
      list = manager.discover(openidIdentifier);
    } catch (DiscoveryException e) {
-      log.error("Cannot discover OpenID " + openidIdentifier, e);
+      logger.atSevere().withCause(e).log("Cannot discover OpenID %s", openidIdentifier);
      return null;
    }
    if (list == null || list.isEmpty()) {
--- a/java/com/google/gerrit/httpd/gitweb/GitwebServlet.java
+++ b/java/com/google/gerrit/httpd/gitweb/GitwebServlet.java
@@ -34,6 +34,7 @@ import static java.nio.charset.StandardCharsets.UTF_8;

 import com.google.common.base.CharMatcher;
 import com.google.common.base.Splitter;
+import com.google.common.flogger.FluentLogger;
 import com.google.gerrit.common.PageLinks;
 import com.google.gerrit.extensions.restapi.AuthException;
 import com.google.gerrit.extensions.restapi.ResourceConflictException;
@@ -85,14 +86,12 @@ import javax.servlet.http.HttpServletResponse;
 import org.eclipse.jgit.errors.RepositoryNotFoundException;
 import org.eclipse.jgit.lib.Config;
 import org.eclipse.jgit.lib.Repository;
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;

 /** Invokes {@code gitweb.cgi} for the project given in {@code p}. */
@SuppressWarnings("serial")
@Singleton
 class GitwebServlet extends HttpServlet {
-  private static final Logger log = LoggerFactory.getLogger(GitwebServlet.class);
+  private static final FluentLogger logger = FluentLogger.forEnclosingClass();

  private static final String PROJECT_LIST_ACTION = "project_list";

@@ -137,7 +136,7 @@ class GitwebServlet extends HttpServlet {
      try {
        uri = new URI(url);
      } catch (URISyntaxException e) {
-        log.error("Invalid gitweb.url: " + url);
+        logger.atSevere().log("Invalid gitweb.url: %s", url);
      }
      gitwebUrl = uri;
    } else {
@@ -428,7 +427,7 @@ class GitwebServlet extends HttpServlet {
      sendErrorOrRedirect(req, rsp, HttpServletResponse.SC_NOT_FOUND);
      return;
    } catch (IOException | PermissionBackendException err) {
-      log.error("cannot load " + name, err);
+      logger.atSevere().withCause(err).log("cannot load %s", name);
      rsp.sendError(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
      return;
    } catch (ResourceConflictException e) {
@@ -528,13 +527,13 @@ class GitwebServlet extends HttpServlet {

      final int status = proc.exitValue();
      if (0 != status) {
-        log.error("Non-zero exit status (" + status + ") from " + gitwebCgi);
+        logger.atSevere().log("Non-zero exit status (%d) from %s", status, gitwebCgi);
        if (!rsp.isCommitted()) {
          rsp.sendError(500);
        }
      }
    } catch (InterruptedException ie) {
-      log.debug("CGI: interrupted waiting for CGI to terminate");
+      logger.atFine().log("CGI: interrupted waiting for CGI to terminate");
    }
  }

@@ -659,7 +658,7 @@ class GitwebServlet extends HttpServlet {
                  dst.close();
                }
              } catch (IOException e) {
-                log.error("Unexpected error copying input to CGI", e);
+                logger.atSevere().withCause(e).log("Unexpected error copying input to CGI");
              }
            },
            "Gitweb-InputFeeder")
@@ -679,9 +678,9 @@ class GitwebServlet extends HttpServlet {
                  }
                  b.append("CGI: ").append(line);
                }
-                log.error(b.toString());
+                logger.atSevere().log(b.toString());
              } catch (IOException e) {
-                log.error("Unexpected error copying stderr from CGI", e);
+                logger.atSevere().withCause(e).log("Unexpected error copying stderr from CGI");
              }
            },
            "Gitweb-ErrorLogger")
--- a/java/com/google/gerrit/httpd/init/BUILD
+++ b/java/com/google/gerrit/httpd/init/BUILD
@@ -27,10 +27,10 @@ java_library(
        "//lib:guava",
        "//lib:gwtorm",
        "//lib:servlet-api-3_1",
+        "//lib/flogger:api",
        "//lib/guice",
        "//lib/guice:guice-servlet",
        "//lib/jgit/org.eclipse.jgit:jgit",
-        "//lib/log:api",
        "//prolog:gerrit-prolog-common",
    ],
 )
--- a/java/com/google/gerrit/httpd/init/SiteInitializer.java
+++ b/java/com/google/gerrit/httpd/init/SiteInitializer.java
@@ -14,6 +14,7 @@

 package com.google.gerrit.httpd.init;

+import com.google.common.flogger.FluentLogger;
 import com.google.gerrit.pgm.init.BaseInit;
 import com.google.gerrit.pgm.init.PluginsDistribution;
 import java.nio.file.Path;
@@ -23,11 +24,9 @@ import java.sql.ResultSet;
 import java.sql.SQLException;
 import java.sql.Statement;
 import java.util.List;
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;

 public final class SiteInitializer {
-  private static final Logger LOG = LoggerFactory.getLogger(SiteInitializer.class);
+  private static final FluentLogger logger = FluentLogger.forEnclosingClass();

  private final String sitePath;
  private final String initPath;
@@ -49,7 +48,7 @@ public final class SiteInitializer {
    try {
      if (sitePath != null) {
        Path site = Paths.get(sitePath);
-        LOG.info("Initializing site at " + site.toRealPath().normalize());
+        logger.atInfo().log("Initializing site at %s", site.toRealPath().normalize());
        new BaseInit(site, false, true, pluginsDistribution, pluginsToInstall).run();
        return;
      }
@@ -60,7 +59,7 @@ public final class SiteInitializer {
          site = Paths.get(initPath);
        }
        if (site != null) {
-          LOG.info("Initializing site at " + site.toRealPath().normalize());
+          logger.atInfo().log("Initializing site at %s", site.toRealPath().normalize());
          new BaseInit(
                  site,
                  new ReviewDbDataSourceProvider(),
@@ -72,7 +71,7 @@ public final class SiteInitializer {
        }
      }
    } catch (Exception e) {
-      LOG.error("Site init failed", e);
+      logger.atSevere().withCause(e).log("Site init failed");
      throw new RuntimeException(e);
    }
  }
--- a/java/com/google/gerrit/httpd/init/WebAppInitializer.java
+++ b/java/com/google/gerrit/httpd/init/WebAppInitializer.java
@@ -18,6 +18,7 @@ import static com.google.inject.Scopes.SINGLETON;
 import static com.google.inject.Stage.PRODUCTION;

 import com.google.common.base.Splitter;
+import com.google.common.flogger.FluentLogger;
 import com.google.gerrit.elasticsearch.ElasticIndexModule;
 import com.google.gerrit.extensions.client.AuthType;
 import com.google.gerrit.gpg.GpgModule;
@@ -127,12 +128,10 @@ import javax.servlet.ServletResponse;
 import javax.servlet.http.HttpServletRequest;
 import javax.sql.DataSource;
 import org.eclipse.jgit.lib.Config;
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;

 /** Configures the web application environment for Gerrit Code Review. */
 public class WebAppInitializer extends GuiceServletContextListener implements Filter {
-  private static final Logger log = LoggerFactory.getLogger(WebAppInitializer.class);
+  private static final FluentLogger logger = FluentLogger.forEnclosingClass();

  private Path sitePath;
  private Injector dbInjector;
@@ -194,7 +193,7 @@ public class WebAppInitializer extends GuiceServletContextListener implements Fi
          buf.append("\nResolve above errors before continuing.");
          buf.append("\nComplete stack trace follows:");
        }
-        log.error(buf.toString(), first.getCause());
+        logger.atSevere().withCause(first.getCause()).log(buf.toString());
        throw new CreationException(Collections.singleton(first));
      }

--- a/java/com/google/gerrit/httpd/plugins/HttpPluginServlet.java
+++ b/java/com/google/gerrit/httpd/plugins/HttpPluginServlet.java
@@ -32,6 +32,7 @@ import com.google.common.base.Strings;
 import com.google.common.cache.Cache;
 import com.google.common.collect.Lists;
 import com.google.common.collect.Maps;
+import com.google.common.flogger.FluentLogger;
 import com.google.common.io.ByteStreams;
 import com.google.common.net.HttpHeaders;
 import com.google.gerrit.extensions.registration.RegistrationHandle;
@@ -92,14 +93,13 @@ import org.apache.commons.lang.StringUtils;
 import org.eclipse.jgit.lib.Config;
 import org.eclipse.jgit.util.IO;
 import org.eclipse.jgit.util.RawParseUtils;
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;

@Singleton
 class HttpPluginServlet extends HttpServlet implements StartPluginListener, ReloadPluginListener {
+  private static final FluentLogger logger = FluentLogger.forEnclosingClass();
+
  private static final int SMALL_RESOURCE = 128 * 1024;
  private static final long serialVersionUID = 1L;
-  private static final Logger log = LoggerFactory.getLogger(HttpPluginServlet.class);

  private final MimeUtilFileTypeRegistry mimeUtil;
  private final Provider<String> webUrl;
@@ -191,7 +191,7 @@ class HttpPluginServlet extends HttpServlet implements StartPluginListener, Relo
      try {
        filter = plugin.getHttpInjector().getInstance(GuiceFilter.class);
      } catch (RuntimeException e) {
-        log.warn("Plugin {} cannot load GuiceFilter", name, e);
+        logger.atWarning().withCause(e).log("Plugin %s cannot load GuiceFilter", name);
        return null;
      }

@@ -199,7 +199,7 @@ class HttpPluginServlet extends HttpServlet implements StartPluginListener, Relo
        ServletContext ctx = PluginServletContext.create(plugin, wrapper.getFullPath(name));
        filter.init(new WrappedFilterConfig(ctx));
      } catch (ServletException e) {
-        log.warn("Plugin {} failed to initialize HTTP", name, e);
+        logger.atWarning().withCause(e).log("Plugin %s failed to initialize HTTP", name);
        return null;
      }

@@ -423,12 +423,12 @@ class HttpPluginServlet extends HttpServlet implements StartPluginListener, Relo
              && (name.endsWith(".md") || name.endsWith(".html"))
              && size.isPresent()) {
            if (size.get() <= 0 || size.get() > SMALL_RESOURCE) {
-              log.warn(
-                  "Plugin {}: {} omitted from document index. Size {} out of range (0,{}).",
-                  pluginName,
-                  name.substring(prefix.length()),
-                  size.get(),
-                  SMALL_RESOURCE);
+              logger
+                  .atWarning()
+                  .log(
+                      "Plugin %s: %s omitted from document index. "
+                          + "Size %d out of range (0,%d).",
+                      pluginName, name.substring(prefix.length()), size.get(), SMALL_RESOURCE);
              return false;
            }
            return true;
@@ -450,10 +450,11 @@ class HttpPluginServlet extends HttpServlet implements StartPluginListener, Relo
        if (about == null) {
          about = entry;
        } else {
-          log.warn(
-              "Plugin {}: Multiple 'about' documents found; using {}",
-              pluginName,
-              about.getName().substring(prefix.length()));
+          logger
+              .atWarning()
+              .log(
+                  "Plugin %s: Multiple 'about' documents found; using %s",
+                  pluginName, about.getName().substring(prefix.length()));
        }
      } else {
        docs.add(entry);
@@ -731,7 +732,10 @@ class HttpPluginServlet extends HttpServlet implements StartPluginListener, Relo
        }
        return def;
      } catch (IOException e) {
-        log.warn("Error getting {} for plugin {}, using default", attr, plugin.getName(), e);
+        logger
+            .atWarning()
+            .withCause(e)
+            .log("Error getting %s for plugin %s, using default", attr, plugin.getName());
        return null;
      }
    }
--- a/java/com/google/gerrit/httpd/plugins/LfsPluginServlet.java
+++ b/java/com/google/gerrit/httpd/plugins/LfsPluginServlet.java
@@ -18,6 +18,7 @@ import static com.google.gerrit.extensions.api.lfs.LfsDefinitions.CONTENTTYPE_VN
 import static java.nio.charset.StandardCharsets.UTF_8;
 import static javax.servlet.http.HttpServletResponse.SC_NOT_IMPLEMENTED;

+import com.google.common.flogger.FluentLogger;
 import com.google.gerrit.extensions.registration.RegistrationHandle;
 import com.google.gerrit.httpd.resources.Resource;
 import com.google.gerrit.server.config.GerritServerConfig;
@@ -45,14 +46,14 @@ import javax.servlet.http.HttpServlet;
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
 import org.eclipse.jgit.lib.Config;
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;

@Singleton
 public class LfsPluginServlet extends HttpServlet
    implements StartPluginListener, ReloadPluginListener {
  private static final long serialVersionUID = 1L;
-  private static final Logger log = LoggerFactory.getLogger(LfsPluginServlet.class);
+
+  private static final FluentLogger logger = FluentLogger.forEnclosingClass();
+
  private static final String MESSAGE_LFS_NOT_CONFIGURED =
      "{\"message\":\"No LFS plugin is configured to handle LFS requests.\"}";

@@ -139,7 +140,7 @@ public class LfsPluginServlet extends HttpServlet
      try {
        guiceFilter = plugin.getHttpInjector().getInstance(GuiceFilter.class);
      } catch (RuntimeException e) {
-        log.warn("Plugin {} cannot load GuiceFilter", name, e);
+        logger.atWarning().withCause(e).log("Plugin %s cannot load GuiceFilter", name);
        return null;
      }

@@ -147,7 +148,7 @@ public class LfsPluginServlet extends HttpServlet
        ServletContext ctx = PluginServletContext.create(plugin, "/");
        guiceFilter.init(new WrappedFilterConfig(ctx));
      } catch (ServletException e) {
-        log.warn("Plugin {} failed to initialize HTTP", name, e);
+        logger.atWarning().withCause(e).log("Plugin %s failed to initialize HTTP", name);
        return null;
      }

--- a/java/com/google/gerrit/httpd/plugins/PluginServletContext.java
+++ b/java/com/google/gerrit/httpd/plugins/PluginServletContext.java
@@ -15,6 +15,7 @@
 package com.google.gerrit.httpd.plugins;

 import com.google.common.collect.Maps;
+import com.google.common.flogger.FluentLogger;
 import com.google.gerrit.common.Version;
 import com.google.gerrit.server.plugins.Plugin;
 import java.io.InputStream;
@@ -29,11 +30,9 @@ import java.util.concurrent.ConcurrentMap;
 import javax.servlet.RequestDispatcher;
 import javax.servlet.Servlet;
 import javax.servlet.ServletContext;
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;

 class PluginServletContext {
-  private static final Logger log = LoggerFactory.getLogger(PluginServletContext.class);
+  private static final FluentLogger logger = FluentLogger.forEnclosingClass();

  static ServletContext create(Plugin plugin, String contextPath) {
    return (ServletContext)
@@ -155,7 +154,7 @@ class PluginServletContext {

    @Override
    public void log(String msg, Throwable reason) {
-      log.warn("[plugin {}] {}", plugin.getName(), msg, reason);
+      logger.atWarning().withCause(reason).log("[plugin %s] %s", plugin.getName(), msg);
    }

    @Override
--- a/java/com/google/gerrit/httpd/raw/BazelBuild.java
+++ b/java/com/google/gerrit/httpd/raw/BazelBuild.java
@@ -19,6 +19,7 @@ import static java.nio.charset.StandardCharsets.UTF_8;

 import com.google.common.base.Joiner;
 import com.google.common.escape.Escaper;
+import com.google.common.flogger.FluentLogger;
 import com.google.common.html.HtmlEscapers;
 import com.google.common.io.ByteStreams;
 import com.google.gerrit.common.TimeUtil;
@@ -33,11 +34,9 @@ import java.nio.file.Path;
 import java.util.Properties;
 import javax.servlet.http.HttpServletResponse;
 import org.eclipse.jgit.util.RawParseUtils;
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;

 public class BazelBuild {
-  private static final Logger log = LoggerFactory.getLogger(BazelBuild.class);
+  private static final FluentLogger logger = FluentLogger.forEnclosingClass();

  private final Path sourceRoot;

@@ -49,7 +48,7 @@ public class BazelBuild {
  public void build(Label label) throws IOException, BuildFailureException {
    ProcessBuilder proc = newBuildProcess(label);
    proc.directory(sourceRoot.toFile()).redirectErrorStream(true);
-    log.info("building " + label.fullName());
+    logger.atInfo().log("building %s", label.fullName());
    long start = TimeUtil.nowMs();
    Process rebuild = proc.start();
    byte[] out;
@@ -67,12 +66,12 @@ public class BazelBuild {
          "interrupted waiting for: " + Joiner.on(' ').join(proc.command()));
    }
    if (status != 0) {
-      log.warn("build failed: " + new String(out, UTF_8));
+      logger.atWarning().log("build failed: %s", new String(out, UTF_8));
      throw new BuildFailureException(out);
    }

    long time = TimeUtil.nowMs() - start;
-    log.info(String.format("UPDATED    %s in %.3fs", label.fullName(), time / 1000.0));
+    logger.atInfo().log("UPDATED    %s in %.3fs", label.fullName(), time / 1000.0);
  }

  // Represents a label in bazel.
--- a/java/com/google/gerrit/httpd/raw/HostPageServlet.java
+++ b/java/com/google/gerrit/httpd/raw/HostPageServlet.java
@@ -18,6 +18,7 @@ import static com.google.gerrit.common.FileUtil.lastModified;
 import static java.nio.charset.StandardCharsets.UTF_8;

 import com.google.common.base.Strings;
+import com.google.common.flogger.FluentLogger;
 import com.google.common.hash.Hasher;
 import com.google.common.hash.Hashing;
 import com.google.common.primitives.Bytes;
@@ -60,8 +61,6 @@ import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
 import org.eclipse.jgit.errors.ConfigInvalidException;
 import org.eclipse.jgit.lib.Config;
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
 import org.w3c.dom.Document;
 import org.w3c.dom.Element;
 import org.w3c.dom.Node;
@@ -70,7 +69,7 @@ import org.w3c.dom.Node;
@SuppressWarnings("serial")
@Singleton
 public class HostPageServlet extends HttpServlet {
-  private static final Logger log = LoggerFactory.getLogger(HostPageServlet.class);
+  private static final FluentLogger logger = FluentLogger.forEnclosingClass();

  private static final String HPD_ID = "gerrit_hostpagedata";
  private static final int DEFAULT_JS_LOAD_TIMEOUT = 5000;
@@ -141,7 +140,7 @@ public class HostPageServlet extends HttpServlet {
        }
        src += "?content=" + md.hash().toString();
      } else {
-        log.debug("No " + src + " in webapp root; keeping noncache.js URL");
+        logger.atFine().log("No %s in webapp root; keeping noncache.js URL", src);
      }
    } catch (IOException e) {
      throw new IOException("Failed reading " + src, e);
@@ -173,7 +172,7 @@ public class HostPageServlet extends HttpServlet {
        page = p;
      }
    } catch (IOException e) {
-      log.error("Cannot refresh site header/footer", e);
+      logger.atSevere().withCause(e).log("Cannot refresh site header/footer");
    }
    return p;
  }
@@ -225,7 +224,7 @@ public class HostPageServlet extends HttpServlet {
        | ConfigInvalidException
        | IOException
        | PermissionBackendException e) {
-      log.warn("Cannot query account diff preferences", e);
+      logger.atWarning().withCause(e).log("Cannot query account diff preferences");
    }
    return DiffPreferencesInfo.defaults();
  }
--- a/java/com/google/gerrit/httpd/raw/ResourceServlet.java
+++ b/java/com/google/gerrit/httpd/raw/ResourceServlet.java
@@ -30,6 +30,7 @@ import com.google.common.annotations.VisibleForTesting;
 import com.google.common.base.CharMatcher;
 import com.google.common.cache.Cache;
 import com.google.common.collect.ImmutableMap;
+import com.google.common.flogger.FluentLogger;
 import com.google.common.hash.Hashing;
 import com.google.gerrit.common.Nullable;
 import com.google.gerrit.httpd.HtmlDomUtil;
@@ -47,8 +48,6 @@ import java.util.zip.GZIPOutputStream;
 import javax.servlet.http.HttpServlet;
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;

 /**
 * Base class for serving static resources.
@@ -58,7 +57,7 @@ import org.slf4j.LoggerFactory;
 public abstract class ResourceServlet extends HttpServlet {
  private static final long serialVersionUID = 1L;

-  private static final Logger log = LoggerFactory.getLogger(ResourceServlet.class);
+  private static final FluentLogger logger = FluentLogger.forEnclosingClass();

  private static final int CACHE_FILE_SIZE_LIMIT_BYTES = 100 << 10;

@@ -161,7 +160,7 @@ public abstract class ResourceServlet extends HttpServlet {
        r = cache.get(p, newLoader(p));
      }
    } catch (ExecutionException e) {
-      log.warn("Cannot load static resource {}", req.getPathInfo(), e);
+      logger.atWarning().withCause(e).log("Cannot load static resource %s", req.getPathInfo());
      CacheHeaders.setNotCacheable(rsp);
      rsp.setStatus(SC_INTERNAL_SERVER_ERROR);
      return;
@@ -214,12 +213,12 @@ public abstract class ResourceServlet extends HttpServlet {
    try {
      Path p = getResourcePath(name);
      if (p == null) {
-        log.warn("Path doesn't exist {}", name);
+        logger.atWarning().log("Path doesn't exist %s", name);
        return null;
      }
      return cache.get(p, newLoader(p));
    } catch (ExecutionException | IOException e) {
-      log.warn("Cannot load static resource {}", name, e);
+      logger.atWarning().withCause(e).log("Cannot load static resource %s", name);
      return null;
    }
  }
--- a/java/com/google/gerrit/httpd/raw/StaticModule.java
+++ b/java/com/google/gerrit/httpd/raw/StaticModule.java
@@ -21,6 +21,7 @@ import static java.nio.file.Files.isReadable;

 import com.google.common.cache.Cache;
 import com.google.common.collect.ImmutableList;
+import com.google.common.flogger.FluentLogger;
 import com.google.gerrit.common.Nullable;
 import com.google.gerrit.extensions.client.UiType;
 import com.google.gerrit.httpd.XsrfCookieFilter;
@@ -57,11 +58,9 @@ import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletRequestWrapper;
 import javax.servlet.http.HttpServletResponse;
 import org.eclipse.jgit.lib.Config;
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;

 public class StaticModule extends ServletModule {
-  private static final Logger log = LoggerFactory.getLogger(StaticModule.class);
+  private static final FluentLogger logger = FluentLogger.forEnclosingClass();

  public static final String CACHE = "static_content";
  public static final String GERRIT_UI_COOKIE = "GERRIT_UI";
@@ -184,7 +183,7 @@ public class StaticModule extends ServletModule {
        if (exists(configPath) && isReadable(configPath)) {
          return new SingleFileServlet(cache, configPath, true);
        }
-        log.warn("Cannot read httpd.robotsFile, using default");
+        logger.atWarning().log("Cannot read httpd.robotsFile, using default");
      }
      Paths p = getPaths();
      if (p.warFs != null) {
--- a/java/com/google/gerrit/httpd/restapi/RestApiServlet.java
+++ b/java/com/google/gerrit/httpd/restapi/RestApiServlet.java
@@ -58,6 +58,7 @@ import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.Iterables;
 import com.google.common.collect.ListMultimap;
 import com.google.common.collect.Lists;
+import com.google.common.flogger.FluentLogger;
 import com.google.common.io.BaseEncoding;
 import com.google.common.io.CountingOutputStream;
 import com.google.common.math.IntMath;
@@ -164,12 +165,11 @@ import org.eclipse.jgit.http.server.ServletUtils;
 import org.eclipse.jgit.lib.Config;
 import org.eclipse.jgit.util.TemporaryBuffer;
 import org.eclipse.jgit.util.TemporaryBuffer.Heap;
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;

 public class RestApiServlet extends HttpServlet {
  private static final long serialVersionUID = 1L;
-  private static final Logger log = LoggerFactory.getLogger(RestApiServlet.class);
+
+  private static final FluentLogger logger = FluentLogger.forEnclosingClass();

  /** MIME type used for a JSON response body. */
  private static final String JSON_TYPE = "application/json";
@@ -1192,7 +1192,7 @@ public class RestApiServlet extends HttpServlet {
    if (!Strings.isNullOrEmpty(req.getQueryString())) {
      uri += "?" + req.getQueryString();
    }
-    log.error("Error in {} {}", req.getMethod(), uri, err);
+    logger.atSevere().withCause(err).log("Error in %s %s", req.getMethod(), uri);

    if (!res.isCommitted()) {
      res.reset();
--- a/java/com/google/gerrit/httpd/rpc/GerritJsonServlet.java
+++ b/java/com/google/gerrit/httpd/rpc/GerritJsonServlet.java
@@ -16,6 +16,7 @@ package com.google.gerrit.httpd.rpc;

 import com.google.common.collect.ListMultimap;
 import com.google.common.collect.MultimapBuilder;
+import com.google.common.flogger.FluentLogger;
 import com.google.gerrit.common.TimeUtil;
 import com.google.gerrit.common.audit.Audit;
 import com.google.gerrit.common.auth.SignInRequired;
@@ -38,13 +39,12 @@ import java.lang.reflect.Field;
 import java.lang.reflect.Method;
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;

 /** Base JSON servlet to ensure the current user is not forged. */
@SuppressWarnings("serial")
 final class GerritJsonServlet extends JsonServlet<GerritJsonServlet.GerritCall> {
-  private static final Logger log = LoggerFactory.getLogger(GerritJsonServlet.class);
+  private static final FluentLogger logger = FluentLogger.forEnclosingClass();
+
  private static final ThreadLocal<GerritCall> currentCall = new ThreadLocal<>();
  private static final ThreadLocal<MethodHandle> currentMethod = new ThreadLocal<>();
  private final DynamicItem<WebSession> session;
@@ -141,7 +141,7 @@ final class GerritJsonServlet extends JsonServlet<GerritJsonServlet.GerritCall>
                result));
      }
    } catch (Throwable all) {
-      log.error("Unable to log the call", all);
+      logger.atSevere().withCause(all).log("Unable to log the call");
    }
  }

@@ -190,7 +190,7 @@ final class GerritJsonServlet extends JsonServlet<GerritJsonServlet.GerritCall>
        declaredField = clazz.getDeclaredField(fieldName);
        declaredField.setAccessible(true);
      } catch (Exception e) {
-        log.error("Unable to expose RPS/JSON result field");
+        logger.atSevere().log("Unable to expose RPS/JSON result field");
      }
      return declaredField;
    }
@@ -205,9 +205,9 @@ final class GerritJsonServlet extends JsonServlet<GerritJsonServlet.GerritCall>
        Method method = (Method) methodField.get(this.getMethod());
        return method.getDeclaringClass();
      } catch (IllegalArgumentException e) {
-        log.error("Cannot access result field");
+        logger.atSevere().log("Cannot access result field");
      } catch (IllegalAccessException e) {
-        log.error("No permissions to access result field");
+        logger.atSevere().log("No permissions to access result field");
      }

      return null;
@@ -222,9 +222,9 @@ final class GerritJsonServlet extends JsonServlet<GerritJsonServlet.GerritCall>
      try {
        return resultField.get(this);
      } catch (IllegalArgumentException e) {
-        log.error("Cannot access result field");
+        logger.atSevere().log("Cannot access result field");
      } catch (IllegalAccessException e) {
-        log.error("No permissions to access result field");
+        logger.atSevere().log("No permissions to access result field");
      }

      return null;
--- a/java/com/google/gerrit/httpd/rpc/SystemInfoServiceImpl.java
+++ b/java/com/google/gerrit/httpd/rpc/SystemInfoServiceImpl.java
@@ -14,6 +14,7 @@

 package com.google.gerrit.httpd.rpc;

+import com.google.common.flogger.FluentLogger;
 import com.google.gerrit.common.data.SshHostKey;
 import com.google.gerrit.common.data.SystemInfoService;
 import com.google.gerrit.server.ssh.SshInfo;
@@ -26,11 +27,9 @@ import com.jcraft.jsch.JSch;
 import java.util.ArrayList;
 import java.util.List;
 import javax.servlet.http.HttpServletRequest;
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;

 class SystemInfoServiceImpl implements SystemInfoService {
-  private static final Logger log = LoggerFactory.getLogger(SystemInfoServiceImpl.class);
+  private static final FluentLogger logger = FluentLogger.forEnclosingClass();

  private static final JSch JSCH = new JSch();

@@ -63,7 +62,7 @@ class SystemInfoServiceImpl implements SystemInfoService {
    HttpServletRequest r = httpRequest.get();
    String ua = r.getHeader("User-Agent");
    message = message.replaceAll("\n", "\n  ");
-    log.error("Client UI JavaScript error: User-Agent=" + ua + ": " + message);
+    logger.atSevere().log("Client UI JavaScript error: User-Agent=%s: %s", ua, message);
    callback.onSuccess(VoidResult.INSTANCE);
  }
 }
--- a/java/com/google/gerrit/httpd/template/SiteHeaderFooter.java
+++ b/java/com/google/gerrit/httpd/template/SiteHeaderFooter.java
@@ -17,6 +17,7 @@ package com.google.gerrit.httpd.template;
 import static com.google.gerrit.common.FileUtil.lastModified;

 import com.google.common.base.Strings;
+import com.google.common.flogger.FluentLogger;
 import com.google.gerrit.httpd.HtmlDomUtil;
 import com.google.gerrit.server.config.GerritServerConfig;
 import com.google.gerrit.server.config.SitePaths;
@@ -25,14 +26,12 @@ import com.google.inject.Singleton;
 import java.io.IOException;
 import java.nio.file.Path;
 import org.eclipse.jgit.lib.Config;
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
 import org.w3c.dom.Document;
 import org.w3c.dom.Element;

@Singleton
 public class SiteHeaderFooter {
-  private static final Logger log = LoggerFactory.getLogger(SiteHeaderFooter.class);
+  private static final FluentLogger logger = FluentLogger.forEnclosingClass();

  private final boolean refreshHeaderFooter;
  private final SitePaths sitePaths;
@@ -48,7 +47,7 @@ public class SiteHeaderFooter {
      t.load();
      template = t;
    } catch (IOException e) {
-      log.warn("Cannot load site header or footer", e);
+      logger.atWarning().withCause(e).log("Cannot load site header or footer");
    }
  }

@@ -60,7 +59,7 @@ public class SiteHeaderFooter {
        t.load();
        template = t;
      } catch (IOException e) {
-        log.warn("Cannot refresh site header or footer", e);
+        logger.atWarning().withCause(e).log("Cannot refresh site header or footer");
        t = template;
      }
    }