Google Git
Sign in
gerrit / plugins / multi-site / 89d497605c85b3422f2b6958cca1df3fc2dd532f
commit89d497605c85b3422f2b6958cca1df3fc2dd532f[log] [tgz]
authorLuca Milanesio <luca.milanesio@gmail.com>Sat Apr 20 22:24:08 2024 +0100
committerLuca Milanesio <luca.milanesio@gmail.com>Sat Apr 20 21:29:03 2024 +0000
tree3dcfe664431595b6795ad731960da44ed683f425
parent1df24549848cf15a077d54b9cea99ed8e6a8d07f [diff]
Check for existence of change's target SHA1 for reindexing

When the target branch of a change was advancing rapidly,
the reindexing retries applied by the ForwardedIndexingHandlerWithRetries
were continuing potentially forever as they were waiting to
see the target branch's expected SHA1 for the event.

Whilst it is vital to wait for a target branch SHA1 to appear before
reindexing a change on a remote site, it isn't essential to have
that SHA1 being *exactly* the tip of the target branch, as that
moment can be easily missed.

Example:
- Create two changes C1 and C2 in parallel and push them with
  %submit option
- The changes C1 and C2 will trigger the rapid advance of their
  target SHA1
- The other nodes may reindex C1 but not C2 because the target branch
  has advanced more than expected

Checking simply the existence of the target SHA1 in the repository
is enough to satisfy the conditions for the change being reindexed.

Bug: Issue 335353379
Change-Id: Ife361ec3378a60c0d1eb15df0f9570d569adc07a
1 file changed
tree: 3dcfe664431595b6795ad731960da44ed683f425
  1. .settings/
  2. e2e-tests/
  3. images/
  4. setup_local_env/
  5. src/
  6. .bazelrc
  7. .gitignore
  8. .mailmap
  9. BUILD
  10. DESIGN.md
  11. Jenkinsfile
  12. LICENSE
  13. README.md
README.md

Gerrit multi-site plugin

This plugin allows to deploy a distributed cluster of multiple Gerrit masters each using a separate site without sharing any storage. The alignment between the masters happens using the replication plugin and an external message broker.

Requirements for the Gerrit masters are:

  • Gerrit v2.16.5 or later
  • Migrated to NoteDb
  • Connected to the same message broker
  • Accessible via a load balancer (e.g. HAProxy)

NOTE: The multi-site plugin will not start if Gerrit is not yet migrated to NoteDb.

Supports multiple read/write masters across multiple sites across different geographic locations. The Gerrit nodes are kept synchronized between each other using the replication plugin and a global ref-database in order to detect and prevent split-brains.

For more details on the overall multi-site design and roadmap, please refer to the multi-site plugin DESIGN.md document

License

This plugin is released under the same Apache 2.0 license and copyright holders as of the Gerrit Code Review project.

How to build

The multi-site plugin can only be built in tree mode, by cloning Gerrit and the multi-site plugin code, and checking them out on the desired branch.

Example of cloning Gerrit and multi-site for a stable-2.16 build:

git clone -b stable-2.16 https://gerrit.googlesource.com/gerrit
git clone -b stable-2.16 https://gerrit.googlesource.com/plugins/multi-site

cd gerrit/plugins
ln -s ../../multi-site .

Example of building the multi-site plugin:

cd gerrit
bazel build plugins/multi-site

The multi-site.jar plugin is generated to bazel-bin/plugins/multi-site/multi-site.jar.

Example of testing the multi-site plugin:

cd gerrit
bazel test plugins/multi-site:multi_site_tests

NOTE: The multi-site tests include also the use of Docker containers for instantiating and using a Kafka/Zookeeper broker. Make sure you have a Docker daemon running (/var/run/docker.sock accessible) or a DOCKER_HOST pointing to a Docker server.

Pre-requisites

Each Gerrit server of the cluster must be identified with a globally unique instance-id defined in $GERRIT_SITE/etc/gerrit.config. When migrating from a multi-site configuration with Gerrit v3.3 or earlier, you must reuse the instance-id value stored under $GERRIT_SITE/data/multi-site.

Example:

[gerrit]
  instanceId = 758fe5b7-1869-46e6-942a-3ae0ae7e3bd2

How to configure

Install the multi-site plugin into the $GERRIT_SITE/lib directory of all the Gerrit servers that are part of the multi-site cluster. Create a symbolic link from $GERRIT_SITE/lib/multi-site.jar into the $GERRIT_SITE/plugins.

Add the multi-site module to $GERRIT_SITE/etc/gerrit.config as follows:

[gerrit]
  installDbModule = com.googlesource.gerrit.plugins.multisite.GitModule
  installModule = com.googlesource.gerrit.plugins.multisite.Module

For more details on the configuration settings, please refer to the multi-site configuration documentation.

You also need to setup the Git-level replication between nodes. This can be done with either pull or push replication plugin.

HTTP endpoints

For information about available HTTP endpoints please refer to the documentation.