Allow to configure mandatory plugins

In gerrit.config we can now define a list of mandatory plugins:

  [plugins]
    mandatory = replication
    mandatory = hooks

If a mandatory plugin does not load, either because it is not present in
the plugins directory or because it fails to load, Gerrit start will
fail.

Change-Id: I26c578051b0f91844bab0a9b46e0fac34d88a15e

Documentation/config-gerrit.txt

@@ -3481,6 +3481,11 @@ Enable remote installation, enable and disable of plugins over HTTP
 and SSH.  If set to true Administrators can install new plugins
 remotely, or disable existing plugins.  Defaults to false.
 
+[[plugins.mandatory]]plugins.mandatory::
++
+List of mandatory plugins. If a plugin from this list does not load,
+Gerrit start will fail.
+
 [[plugins.jsLoadTimeout]]plugins.jsLoadTimeout::
 +
 Set the timeout value for loading JavaScript plugins in Gerrit UI.

java/com/google/gerrit/acceptance/AbstractDaemonTest.java

@@ -215,7 +215,8 @@ public abstract class AbstractDaemonTest {
               beforeTest(description);
               ProjectResetter.Config input = requireNonNull(resetProjects());
 
-              try (ProjectResetter resetter = projectResetter.builder().build(input)) {
+              try (ProjectResetter resetter =
+                  projectResetter != null ? projectResetter.builder().build(input) : null) {
                 AbstractDaemonTest.this.resetter = resetter;
                 base.evaluate();
               } finally {
@@ -298,12 +299,16 @@ public abstract class AbstractDaemonTest {
 
   @Before
   public void clearSender() {
-    sender.clear();
+    if (sender != null) {
+      sender.clear();
+    }
   }
 
   @Before
   public void startEventRecorder() {
-    eventRecorder = eventRecorderFactory.create(admin);
+    if (eventRecorderFactory != null) {
+      eventRecorder = eventRecorderFactory.create(admin);
+    }
   }
 
   @Before
@@ -318,7 +323,9 @@ public abstract class AbstractDaemonTest {
 
   @After
   public void closeEventRecorder() {
-    eventRecorder.close();
+    if (eventRecorder != null) {
+      eventRecorder.close();
+    }
   }
 
   @AfterClass

java/com/google/gerrit/server/plugins/MissingMandatoryPluginsException.java

@@ -0,0 +1,30 @@
+// Copyright (C) 2019 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.gerrit.server.plugins;
+
+import java.util.Collection;
+
+/** Raised when one or more mandatory plugins are missing. */
+public class MissingMandatoryPluginsException extends RuntimeException {
+  private static final long serialVersionUID = 1L;
+
+  public MissingMandatoryPluginsException(Collection<String> pluginNames) {
+    super(getMessage(pluginNames));
+  }
+
+  private static String getMessage(Collection<String> pluginNames) {
+    return String.format("Cannot find or load the following mandatory plugins: %s", pluginNames);
+  }
+}

java/com/google/gerrit/server/plugins/PluginLoader.java

@@ -20,6 +20,7 @@ import com.google.common.base.MoreObjects;
 import com.google.common.base.Strings;
 import com.google.common.collect.ComparisonChain;
 import com.google.common.collect.ImmutableList;
+import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.Iterables;
 import com.google.common.collect.LinkedHashMultimap;
 import com.google.common.collect.Lists;
@@ -50,8 +51,10 @@ import java.nio.file.Paths;
 import java.util.AbstractMap;
 import java.util.ArrayDeque;
 import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.Collection;
 import java.util.Comparator;
+import java.util.HashSet;
 import java.util.Iterator;
 import java.util.List;
 import java.util.Map;
@@ -87,6 +90,7 @@ public class PluginLoader implements LifecycleListener {
   private final Provider<String> urlProvider;
   private final PersistentCacheFactory persistentCacheFactory;
   private final boolean remoteAdmin;
+  private final Set<String> mandatoryPlugins;
   private final UniversalServerPluginProvider serverPluginFactory;
   private final GerritRuntime gerritRuntime;
 
@@ -114,6 +118,8 @@ public class PluginLoader implements LifecycleListener {
     serverPluginFactory = pluginFactory;
 
     remoteAdmin = cfg.getBoolean("plugins", null, "allowRemoteAdmin", false);
+    mandatoryPlugins =
+        ImmutableSet.copyOf(Arrays.asList(cfg.getStringList("plugins", null, "mandatory")));
     this.gerritRuntime = gerritRuntime;
 
     long checkFrequency =
@@ -381,50 +387,57 @@ public class PluginLoader implements LifecycleListener {
   }
 
   public synchronized void rescan() {
+    Set<String> loadedPlugins = new HashSet<>();
     SetMultimap<String, Path> pluginsFiles = prunePlugins(pluginsDir);
-    if (pluginsFiles.isEmpty()) {
-      return;
+
+    if (!pluginsFiles.isEmpty()) {
+      syncDisabledPlugins(pluginsFiles);
+
+      Map<String, Path> activePlugins = filterDisabled(pluginsFiles);
+      for (Map.Entry<String, Path> entry : jarsFirstSortedPluginsSet(activePlugins)) {
+        String name = entry.getKey();
+        Path path = entry.getValue();
+        String fileName = path.getFileName().toString();
+        if (!isUiPlugin(fileName) && !serverPluginFactory.handles(path)) {
+          logger.atWarning().log(
+              "No Plugin provider was found that handles this file format: %s", fileName);
+          continue;
+        }
+
+        FileSnapshot brokenTime = broken.get(name);
+        if (brokenTime != null && !brokenTime.isModified(path.toFile())) {
+          continue;
+        }
+
+        Plugin active = running.get(name);
+        if (active != null && !active.isModified(path)) {
+          loadedPlugins.add(name);
+          continue;
+        }
+
+        if (active != null) {
+          logger.atInfo().log("Reloading plugin %s", active.getName());
+        }
+
+        try {
+          Plugin loadedPlugin = runPlugin(name, path, active);
+          if (!loadedPlugin.isDisabled()) {
+            loadedPlugins.add(name);
+            logger.atInfo().log(
+                "%s plugin %s, version %s",
+                active == null ? "Loaded" : "Reloaded",
+                loadedPlugin.getName(),
+                loadedPlugin.getVersion());
+          }
+        } catch (PluginInstallException e) {
+          logger.atWarning().withCause(e.getCause()).log("Cannot load plugin %s", name);
+        }
+      }
     }
 
-    syncDisabledPlugins(pluginsFiles);
-
-    Map<String, Path> activePlugins = filterDisabled(pluginsFiles);
-    for (Map.Entry<String, Path> entry : jarsFirstSortedPluginsSet(activePlugins)) {
-      String name = entry.getKey();
-      Path path = entry.getValue();
-      String fileName = path.getFileName().toString();
-      if (!isUiPlugin(fileName) && !serverPluginFactory.handles(path)) {
-        logger.atWarning().log(
-            "No Plugin provider was found that handles this file format: %s", fileName);
-        continue;
-      }
-
-      FileSnapshot brokenTime = broken.get(name);
-      if (brokenTime != null && !brokenTime.isModified(path.toFile())) {
-        continue;
-      }
-
-      Plugin active = running.get(name);
-      if (active != null && !active.isModified(path)) {
-        continue;
-      }
-
-      if (active != null) {
-        logger.atInfo().log("Reloading plugin %s", active.getName());
-      }
-
-      try {
-        Plugin loadedPlugin = runPlugin(name, path, active);
-        if (!loadedPlugin.isDisabled()) {
-          logger.atInfo().log(
-              "%s plugin %s, version %s",
-              active == null ? "Loaded" : "Reloaded",
-              loadedPlugin.getName(),
-              loadedPlugin.getVersion());
-        }
-      } catch (PluginInstallException e) {
-        logger.atWarning().withCause(e.getCause()).log("Cannot load plugin %s", name);
-      }
+    Set<String> missingMandatory = Sets.difference(mandatoryPlugins, loadedPlugins);
+    if (!missingMandatory.isEmpty()) {
+      throw new MissingMandatoryPluginsException(missingMandatory);
     }
 
     cleanInBackground();

javatests/com/google/gerrit/acceptance/api/plugin/PluginLoaderIT.java

@@ -0,0 +1,42 @@
+// Copyright (C) 2019 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.gerrit.acceptance.api.plugin;
+
+import com.google.gerrit.acceptance.AbstractDaemonTest;
+import com.google.gerrit.acceptance.GerritConfig;
+import com.google.gerrit.acceptance.NoHttpd;
+import com.google.gerrit.server.plugins.MissingMandatoryPluginsException;
+import org.junit.Test;
+import org.junit.runner.Description;
+
+@NoHttpd
+public class PluginLoaderIT extends AbstractDaemonTest {
+
+  Description testDescription;
+
+  @Override
+  protected void beforeTest(Description description) throws Exception {
+    this.testDescription = description;
+  }
+
+  @Override
+  protected void afterTest() throws Exception {}
+
+  @Test(expected = MissingMandatoryPluginsException.class)
+  @GerritConfig(name = "plugins.mandatory", value = "my-mandatory-plugin")
+  public void shouldFailToStartGerritWhenMandatoryPluginsAreMissing() throws Exception {
+    super.beforeTest(testDescription);
+  }
+}