Merge "Support easy access to global plugin configuration in own config file"

Documentation/dev-plugins.txt

@@ -497,9 +497,9 @@ $ ssh -p 29418 review.example.com sh ls
 $ ssh -p 29418 review.example.com sh ps
 ----
 
-[[configuration]]
-Configuration
--------------
+[[simple-configuration]]
+Simple Configuration in `gerrit.config`
+---------------------------------------
 
 In Gerrit, global configuration is stored in the `gerrit.config` file.
 If a plugin needs global configuration, this configuration should be
@@ -509,12 +509,12 @@ This approach of storing the plugin configuration is only suitable for
 plugins that have a simple configuration that only consists of
 key-value pairs. With this approach it is not possible to have
 subsections in the plugin configuration. Plugins that require a complex
-configuration need to store their configuration in their own
-configuration file where they can make use of subsections. On the other
-hand storing the plugin configuration in a 'plugin' subsection in the
-`gerrit.config` file has the advantage that administrators have all
-configuration parameters in one file, instead of having one
-configuration file per plugin.
+configuration need to store their configuration in their
+link:#configuration[own configuration file] where they can make use of
+subsections. On the other hand storing the plugin configuration in a
+'plugin' subsection in the `gerrit.config` file has the advantage that
+administrators have all configuration parameters in one file, instead
+of having one configuration file per plugin.
 
 To avoid conflicts with other plugins, it is recommended that plugins
 only use the `plugin` subsection with their own name. For example the
@@ -541,6 +541,49 @@ String language = cfg.getFromGerritConfig("helloworld")
                      .getString("language", "English");
 ----
 
+[[configuration]]
+Configuration in own config file
+--------------------------------
+
+Plugins can store their configuration in an own configuration file.
+This makes sense if the plugin configuration is rather complex and
+requires the usage of subsections. Plugins that have a simple
+key-value pair configuration can store their configuration in a
+link:#simple-configuration[`plugin` subsection of the `gerrit.config`
+file].
+
+The plugin configuration file must be named after the plugin and must
+be located in the `etc` folder of the review site. For example a
+configuration file for a `default-reviewer` plugin could look like
+this:
+
+.$site_path/etc/default-reviewer.config
+----
+[branch "refs/heads/master"]
+  reviewer = Project Owners
+  reviewer = john.doe@example.com
+[match "file:^.*\.txt"]
+  reviewer = My Info Developers
+----
+
+Via the `com.google.gerrit.server.config.PluginConfigFactory` class a
+plugin can easily access its configuration:
+
+[source,java]
+----
+@Inject
+private com.google.gerrit.server.config.PluginConfigFactory cfg;
+
+[...]
+
+String[] reviewers = cfg.getGlobalPluginConfig("default-reviewer")
+                        .getStringList("branch", "refs/heads/master", "reviewer");
+----
+
+The plugin configuration is loaded only once and is then cached.
+Similar to changes in 'gerrit.config', changes to the plugin
+configuration file will only become effective after a Gerrit restart.
+
 [[project-specific-configuration]]
 Project Specific Configuration
 ------------------------------

gerrit-server/src/main/java/com/google/gerrit/server/config/PluginConfigFactory.java

@@ -14,6 +14,7 @@
 
 package com.google.gerrit.server.config;
 
+import com.google.common.collect.Maps;
 import com.google.gerrit.reviewdb.client.Project;
 import com.google.gerrit.server.project.NoSuchProjectException;
 import com.google.gerrit.server.project.ProjectCache;
@@ -21,20 +22,36 @@ import com.google.gerrit.server.project.ProjectState;
 import com.google.inject.Inject;
 import com.google.inject.Singleton;
 
+import org.eclipse.jgit.errors.ConfigInvalidException;
 import org.eclipse.jgit.lib.Config;
+import org.eclipse.jgit.storage.file.FileBasedConfig;
+import org.eclipse.jgit.util.FS;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.io.File;
+import java.io.IOException;
+import java.util.Map;
 
 @Singleton
 public class PluginConfigFactory {
+  private static final Logger log =
+      LoggerFactory.getLogger(PluginConfigFactory.class);
+
+  private final SitePaths site;
   private final Config cfg;
   private final ProjectCache projectCache;
   private final ProjectState.Factory projectStateFactory;
+  private final Map<String, Config> pluginConfigs;
 
   @Inject
-  PluginConfigFactory(@GerritServerConfig Config cfg,
+  PluginConfigFactory(SitePaths site, @GerritServerConfig Config cfg,
       ProjectCache projectCache, ProjectState.Factory projectStateFactory) {
+    this.site = site;
     this.cfg = cfg;
     this.projectCache = projectCache;
     this.projectStateFactory = projectStateFactory;
+    this.pluginConfigs = Maps.newHashMap();
   }
 
   /**
@@ -128,4 +145,38 @@ public class PluginConfigFactory {
     return getFromProjectConfig(projectName, pluginName).withInheritance(
         projectStateFactory);
   }
+
+  /**
+   * Returns the configuration for the specified plugin that is stored in the
+   * plugin configuration file 'etc/<plugin-name>.config'.
+   *
+   * The plugin configuration is only loaded once and is then cached.
+   *
+   * @param pluginName the name of the plugin for which the configuration should
+   *        be returned
+   * @return the plugin configuration from the 'etc/<plugin-name>.config' file
+   */
+  public Config getGlobalPluginConfig(String pluginName) {
+    if (pluginConfigs.containsKey(pluginName)) {
+      return pluginConfigs.get(pluginName);
+    }
+
+    File pluginConfigFile = new File(site.etc_dir, pluginName + ".config");
+    FileBasedConfig cfg = new FileBasedConfig(pluginConfigFile, FS.DETECTED);
+    pluginConfigs.put(pluginName, cfg);
+    if (!cfg.getFile().exists()) {
+      log.info("No " + pluginConfigFile.getAbsolutePath() + "; assuming defaults");
+      return cfg;
+    }
+
+    try {
+      cfg.load();
+    } catch (IOException e) {
+      log.warn("Failed to load " + pluginConfigFile.getAbsolutePath(), e);
+    } catch (ConfigInvalidException e) {
+      log.warn("Failed to load " + pluginConfigFile.getAbsolutePath(), e);
+    }
+
+    return cfg;
+  }
 }