Create missing repositories on the remote site

If during the replication of a ref it is found that the repository is
missing on the remote site automatically create it on the remote
site.

E.g. a repository can be missing on the remote site if the remote
site was not available at the moment when a new project was created
and hence the repository for the new project could not be created on
the remote site.

This feature can also help to simplify the setup of a new remote site.

Whether missing repositories should be created or not can be
configured per destination. By default missing repositories are
created. This is a change of the current behaviour but for most
configurations it makes sense that the missing repositories are
created which is why this should be the default.

Change-Id: I4e587cdfca09445c9b1c528b2f1edae0944aec68
Signed-off-by: Edwin Kempin <edwin.kempin@sap.com>
(cherry picked from commit a9fcff5c4d0d99d7bc209431377bdba01ee04c2c)
Reviewed-by: Ismo Haataja <ismo.haataja@digia.com>
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@theqtcompany.com>

4 files changed, 61 insertions, 8 deletions

diff --git a/src/main/java/com/googlesource/gerrit/plugins/replication/Destination.java b/src/main/java/com/googlesource/gerrit/plugins/replication/Destination.java
index 65e9631..1054aed 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/replication/Destination.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/replication/Destination.java
@@ -81,13 +81,14 @@ class Destination {
   private final PushOne.Factory opFactory;
   private final ProjectControl.Factory projectControlFactory;
   private final GitRepositoryManager gitManager;
+  private final boolean createMissingRepos;
   private final boolean replicatePermissions;
   private final String remoteNameStyle;
   private volatile WorkQueue.Executor pool;
   private final PerThreadRequestScope.Scoper threadScoper;
 
   protected static enum RetryReason {
-    TRANSPORT_ERROR, COLLISION;
+    TRANSPORT_ERROR, COLLISION, REPOSITORY_MISSING;
   }
 
   Destination(final Injector injector,
@@ -106,6 +107,8 @@ class Destination {
 
     poolThreads = Math.max(0, getInt(rc, cfg, "threads", 1));
     poolName = "ReplicateTo-" + rc.getName();
+    createMissingRepos =
+        cfg.getBoolean("remote", rc.getName(), "createMissingRepositories", true);
     replicatePermissions =
         cfg.getBoolean("remote", rc.getName(), "replicatePermissions", true);
     remoteNameStyle = Objects.firstNonNull(
@@ -438,6 +441,10 @@ class Destination {
     return false;
   }
 
+  boolean isCreateMissingRepos() {
+    return createMissingRepos;
+  }
+
   boolean isReplicatePermissions() {
     return replicatePermissions;
   }
diff --git a/src/main/java/com/googlesource/gerrit/plugins/replication/PushOne.java b/src/main/java/com/googlesource/gerrit/plugins/replication/PushOne.java
index 596d4ac..897d120 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/replication/PushOne.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/replication/PushOne.java
@@ -21,6 +21,7 @@ import com.google.common.collect.Maps;
 import com.google.common.collect.Multimap;
 import com.google.common.collect.Sets;
 import com.google.gerrit.extensions.events.GitReferenceUpdatedListener;
+import com.google.gerrit.extensions.events.NewProjectCreatedListener;
 import com.google.gerrit.reviewdb.client.Project;
 import com.google.gerrit.reviewdb.server.ReviewDb;
 import com.google.gerrit.server.git.ChangeCache;
@@ -91,6 +92,7 @@ class PushOne implements ProjectRunnable {
   private final TagCache tagCache;
   private final PerThreadRequestScope.Scoper threadScoper;
   private final ChangeCache changeCache;
+  private final ReplicationQueue replicationQueue;
 
   private final Project.NameKey projectName;
   private final URIish uri;
@@ -112,6 +114,7 @@ class PushOne implements ProjectRunnable {
       final TagCache tc,
       final PerThreadRequestScope.Scoper ts,
       final ChangeCache cc,
+      final ReplicationQueue rq,
       @Assisted final Project.NameKey d,
       @Assisted final URIish u) {
     gitManager = grm;
@@ -122,6 +125,7 @@ class PushOne implements ProjectRunnable {
     tagCache = tc;
     threadScoper = ts;
     changeCache = cc;
+    replicationQueue = rq;
     projectName = d;
     uri = u;
   }
@@ -268,7 +272,18 @@ class PushOne implements ProjectRunnable {
       log.error("Cannot replicate " + projectName + "; " + e.getMessage());
 
     } catch (NoRemoteRepositoryException e) {
-      wrappedLog.error("Cannot replicate to " + uri + "; repository not found", getStatesAsArray());
+      if (pool.isCreateMissingRepos()) {
+        try {
+          createRepository();
+          log.warn("Missing repository created; retry replication to " + uri);
+          pool.reschedule(this, Destination.RetryReason.REPOSITORY_MISSING);
+        } catch (IOException ioe) {
+          wrappedLog.error("Cannot replicate to " + uri + "; failed to create missing repository",
+              ioe, getStatesAsArray());
+        }
+      } else {
+        wrappedLog.error("Cannot replicate to " + uri + "; repository not found", getStatesAsArray());
+      }
 
     } catch (NotSupportedException e) {
       wrappedLog.error("Cannot replicate to " + uri, e, getStatesAsArray());
@@ -301,6 +316,23 @@ class PushOne implements ProjectRunnable {
     }
   }
 
+  private void createRepository() throws IOException {
+    final Ref head = git.getRef(Constants.HEAD);
+    NewProjectCreatedListener.Event event =
+        new NewProjectCreatedListener.Event() {
+          @Override
+          public String getProjectName() {
+            return projectName.get();
+          }
+
+          @Override
+          public String getHeadName() {
+            return head != null ? head.getName() : null;
+          }
+        };
+    replicationQueue.onNewProjectCreated(event);
+  }
+
   private void runImpl() throws IOException {
     Transport tn = Transport.open(git, uri);
     PushResult res;
diff --git a/src/main/java/com/googlesource/gerrit/plugins/replication/ReplicationQueue.java b/src/main/java/com/googlesource/gerrit/plugins/replication/ReplicationQueue.java
index a39d61c..502994a 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/replication/ReplicationQueue.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/replication/ReplicationQueue.java
@@ -319,9 +319,11 @@ class ReplicationQueue implements
       try {
         repo.create(true /* bare */);
 
-        RefUpdate u = repo.updateRef(Constants.HEAD);
-        u.disableRefLog();
-        u.link(head);
+        if (head != null) {
+          RefUpdate u = repo.updateRef(Constants.HEAD);
+          u.disableRefLog();
+          u.link(head);
+        }
       } finally {
         repo.close();
       }
@@ -333,9 +335,11 @@ class ReplicationQueue implements
   private static void createRemoteSsh(URIish uri, String head) {
     String quotedPath = QuotedString.BOURNE.quote(uri.getPath());
     String cmd = "mkdir -p " + quotedPath
-            + "&& cd " + quotedPath
-            + "&& git init --bare"
-            + "&& git symbolic-ref HEAD " + QuotedString.BOURNE.quote(head);
+            + " && cd " + quotedPath
+            + " && git init --bare";
+    if (head != null) {
+      cmd = cmd + " && git symbolic-ref HEAD " + QuotedString.BOURNE.quote(head);
+    }
     OutputStream errStream = newErrorBufferStream();
     try {
       RemoteSession ssh = connect(uri);
diff --git a/src/main/resources/Documentation/config.md b/src/main/resources/Documentation/config.md
index 5205025..e22409a 100644
--- a/src/main/resources/Documentation/config.md
+++ b/src/main/resources/Documentation/config.md
@@ -205,6 +205,16 @@ remote.NAME.authGroup
 	By default, replicates without group control, i.e. replicates
 	everything to all remotes.
 
+remote.NAME.createMissingRepositories
+:	If true, a repository is automatically created on the remote site
+	if during the replication of a ref it is found to be missing.
+	E.g. a repository can be missing on the remote site if the remote
+	site was not available at the moment when a new project was created
+	and hence the repository for the new project could not be created on
+	the remote site.
+
+	By default, true, missing repositories are created.
+
 remote.NAME.replicatePermissions
 :	If true, permissions-only projects and the refs/meta/config
 	branch will also be replicated to the remote site.  These