Allow to disable log file rotation

On sites where log file rotation is done by an external service such
as logrotate [1], administrators may wish to disable Gerrit's default
log rotation.

Add a new setting, log.rotate, which disables log rotation when set to
false. The default is true, for backwards compatibility with current
behaviour.

[1] http://manpages.ubuntu.com/manpages/zesty/man8/logrotate.8.html

Change-Id: I76ebf086929fae7dd528e48385265722332dec0a

Documentation/config-gerrit.txt

@@ -3356,6 +3356,12 @@ If set to true, log files are compressed at server startup and then daily at 11p
 +
 Defaults to true.
 
+[[log.rotate]]log.rotate::
++
+If set to true, log files are rotated daily at midnight (GMT).
++
+Defaults to true.
+
 [[mimetype]]
 === Section mimetype
 

java/com/google/gerrit/pgm/util/ErrorLogFile.java

@@ -73,16 +73,18 @@ public class ErrorLogFile {
 
     boolean json = config.getBoolean("log", "jsonLogging", false);
     boolean text = config.getBoolean("log", "textLogging", true) || !json;
+    boolean rotate = config.getBoolean("log", "rotate", true);
 
     if (text) {
       root.addAppender(
           SystemLog.createAppender(
-              logdir, LOG_NAME, new PatternLayout("[%d] [%t] %-5p %c %x: %m%n")));
+              logdir, LOG_NAME, new PatternLayout("[%d] [%t] %-5p %c %x: %m%n"), rotate));
     }
 
     if (json) {
       root.addAppender(
-          SystemLog.createAppender(logdir, LOG_NAME + JSON_SUFFIX, new JSONEventLayoutV1()));
+          SystemLog.createAppender(
+              logdir, LOG_NAME + JSON_SUFFIX, new JSONEventLayoutV1(), rotate));
     }
   }
 }

java/com/google/gerrit/server/git/GarbageCollectionLogFile.java

@@ -15,6 +15,7 @@
 package com.google.gerrit.server.git;
 
 import com.google.gerrit.extensions.events.LifecycleListener;
+import com.google.gerrit.server.config.GerritServerConfig;
 import com.google.gerrit.server.config.SitePaths;
 import com.google.gerrit.server.util.SystemLog;
 import com.google.inject.Inject;
@@ -22,13 +23,13 @@ import java.nio.file.Path;
 import org.apache.log4j.LogManager;
 import org.apache.log4j.Logger;
 import org.apache.log4j.PatternLayout;
+import org.eclipse.jgit.lib.Config;
 
 public class GarbageCollectionLogFile implements LifecycleListener {
-
   @Inject
-  public GarbageCollectionLogFile(SitePaths sitePaths) {
+  public GarbageCollectionLogFile(SitePaths sitePaths, @GerritServerConfig Config config) {
     if (SystemLog.shouldConfigure()) {
-      initLogSystem(sitePaths.logs_dir);
+      initLogSystem(sitePaths.logs_dir, config.getBoolean("log", "rotate", true));
     }
   }
 
@@ -40,12 +41,12 @@ public class GarbageCollectionLogFile implements LifecycleListener {
     LogManager.getLogger(GarbageCollection.LOG_NAME).removeAllAppenders();
   }
 
-  private static void initLogSystem(Path logdir) {
+  private static void initLogSystem(Path logdir, boolean rotate) {
     Logger gcLogger = LogManager.getLogger(GarbageCollection.LOG_NAME);
     gcLogger.removeAllAppenders();
     gcLogger.addAppender(
         SystemLog.createAppender(
-            logdir, GarbageCollection.LOG_NAME, new PatternLayout("[%d] %-5p %x: %m%n")));
+            logdir, GarbageCollection.LOG_NAME, new PatternLayout("[%d] %-5p %x: %m%n"), rotate));
     gcLogger.setAdditivity(false);
   }
 }

java/com/google/gerrit/server/util/SystemLog.java

@@ -27,6 +27,7 @@ import java.nio.file.Path;
 import org.apache.log4j.Appender;
 import org.apache.log4j.AsyncAppender;
 import org.apache.log4j.DailyRollingFileAppender;
+import org.apache.log4j.FileAppender;
 import org.apache.log4j.Layout;
 import org.apache.log4j.LogManager;
 import org.apache.log4j.Logger;
@@ -44,19 +45,21 @@ public class SystemLog {
 
   private final SitePaths site;
   private final int asyncLoggingBufferSize;
+  private final boolean rotateLogs;
 
   @Inject
   public SystemLog(SitePaths site, @GerritServerConfig Config config) {
     this.site = site;
     this.asyncLoggingBufferSize = config.getInt("core", "asyncLoggingBufferSize", 64);
+    this.rotateLogs = config.getBoolean("log", "rotate", true);
   }
 
   public static boolean shouldConfigure() {
     return Strings.isNullOrEmpty(System.getProperty(LOG4J_CONFIGURATION));
   }
 
-  public static Appender createAppender(Path logdir, String name, Layout layout) {
+  public static Appender createAppender(Path logdir, String name, Layout layout, boolean rotate) {
-    final DailyRollingFileAppender dst = new DailyRollingFileAppender();
+    final FileAppender dst = rotate ? new DailyRollingFileAppender() : new FileAppender();
     dst.setName(name);
     dst.setLayout(layout);
     dst.setEncoding(UTF_8.name());
@@ -70,6 +73,10 @@ public class SystemLog {
   }
 
   public AsyncAppender createAsyncAppender(String name, Layout layout) {
+    return createAsyncAppender(name, layout, rotateLogs);
+  }
+
+  private AsyncAppender createAsyncAppender(String name, Layout layout, boolean rotate) {
     AsyncAppender async = new AsyncAppender();
     async.setName(name);
     async.setBlocking(true);
@@ -77,7 +84,7 @@ public class SystemLog {
     async.setLocationInfo(false);
 
     if (shouldConfigure()) {
-      async.addAppender(createAppender(site.logs_dir, name, layout));
+      async.addAppender(createAppender(site.logs_dir, name, layout, rotate));
     } else {
       Appender appender = LogManager.getLogger(name).getAppender(name);
       if (appender != null) {