Custom replication config resource provider from repository

Fetch the override replication config from the All-Projects
repository.

Also-By: Luca Milanesio <luca.milanesio@gmail.com>
Change-Id: I8fd15187fe17ce280d777374e91b2e48604aa43e

replication/replication-config-from-git.groovy

diff --git a/replication/replication-config-from-git.groovy b/replication/replication-config-from-git.groovy
new file mode 100644
index 0000000..efcb32f
--- /dev/null
+++ b/replication/replication-config-from-git.groovy
@@ -0,0 +1,147 @@
+// Copyright (C) 2024 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.
+
+import com.googlesource.gerrit.plugins.replication.*
+  import com.googlesource.gerrit.plugins.replication.FanoutConfigResource.*
+  import com.googlesource.gerrit.plugins.replication.FileConfigResource.*
+
+  import com.google.inject.*
+  import com.google.common.collect.*
+  import com.google.common.flogger.*
+  import com.google.common.io.*
+  import com.google.common.io.Files.*
+  import com.google.gerrit.entities.*
+  import com.google.gerrit.extensions.registration.*
+  import com.google.gerrit.server.config.*
+  import com.google.gerrit.server.git.*
+  import com.google.inject.*
+
+  import java.io.*
+  import java.util.*
+
+  import org.eclipse.jgit.errors.*
+  import org.eclipse.jgit.lib.*
+  import org.eclipse.jgit.lib.FileMode.*
+
+  import org.eclipse.jgit.revwalk.*
+  import org.eclipse.jgit.treewalk.*
+
+  class GitReplicationConfigOverrides implements ReplicationConfigOverrides {
+    FluentLogger logger = FluentLogger.forEnclosingClass()
+    Config EMPTY_CONFIG = new Config()
+
+    def REF_NAME = RefNames.REFS_META + "replication"
+
+    @Inject
+    AllProjectsName allProjectsName
+
+    @Inject
+    GitRepositoryManager repoManager
+
+    @Override
+    Config getConfig() {
+      Config config = EMPTY_CONFIG
+
+      Repository repo = repoManager.openRepository(allProjectsName)
+      RevWalk rw = new RevWalk(repo)
+      try {
+        Ref ref = repo.exactRef(REF_NAME)
+        if (ref) {
+          RevTree tree = rw.parseTree(ref.objectId)
+          config = addFanoutRemotes(repo, tree, getBaseConfig(repo, tree))
+        }
+      } catch (IOException e) {
+        logger.atWarning().withCause(e).log("Cannot read replication config from git repository")
+      } catch (ConfigInvalidException e) {
+        logger.atWarning().withCause(e).log("Cannot parse replication config from git repository")
+      } finally {
+        rw.close()
+        repo.close()
+      }
+
+      config
+    }
+
+    Config getBaseConfig(Repository repo, RevTree tree) {
+      TreeWalk tw = TreeWalk.forPath(repo, FileConfigResource.CONFIG_NAME, tree)
+      return tw ? new BlobBasedConfig(new Config(), repo, tw.getObjectId(0)) : EMPTY_CONFIG
+    }
+
+    Config addFanoutRemotes(Repository repo, RevTree tree, Config destination)
+    throws IOException, ConfigInvalidException {
+      TreeWalk tw = TreeWalk.forPath(repo, FanoutConfigResource.CONFIG_DIR, tree)
+      if (tw) {
+        removeRemotes(destination)
+
+        tw.enterSubtree()
+        while (tw.next()) {
+          if (tw.fileMode == FileMode.REGULAR_FILE && tw.nameString.endsWith(".config")) {
+            Config remoteConfig = new BlobBasedConfig(new Config(), repo, tw.getObjectId(0))
+            addRemoteConfig(tw.nameString, remoteConfig, destination)
+          }
+        }
+      }
+
+      destination
+    }
+
+    def removeRemotes(Config config) {
+      Set < String > remoteNames = config.getSubsections("remote")
+      if (!remoteNames) {
+        logger.atSevere().log(
+          "When replication directory is present replication.config file cannot contain remote configuration. Ignoring: %s",
+          remoteNames.join(","))
+
+        for (String name: remoteNames) {
+          config.unsetSection("remote", name)
+        }
+      }
+    }
+
+    def addRemoteConfig(String fileName, Config source, Config destination) {
+      String remoteName = Files.getNameWithoutExtension(fileName)
+      source.getNames("remote").each {
+        name ->
+          destination.setStringList(
+            "remote",
+            remoteName,
+            name,
+            Lists.newArrayList(source.getStringList("remote", null, name)))
+      }
+    }
+
+    @Override
+    String getVersion() {
+      Repository repo = repoManager.openRepository(allProjectsName)
+      try {
+        ObjectId configHead = repo.resolve(REF_NAME)
+        return configHead ? configHead.name() : ""
+      } catch (IOException e) {
+        throw new IllegalStateException("Could not open replication configuration repository", e)
+      } finally {
+        repo.close()
+      }
+    }
+  }
+
+class GitReplicationConfigModule implements Module {
+
+  @Override
+  void configure(Binder binder) {
+    DynamicItem.bind(binder, ReplicationConfigOverrides.class)
+      .to(GitReplicationConfigOverrides.class)
+  }
+}
+
+modules = [GitReplicationConfigModule]