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gerrit / plugins / multi-site / befad02c0b916a674e5c8000a037df69d70eefee
commitbefad02c0b916a674e5c8000a037df69d70eefee[log] [tgz]
authorLuca Milanesio <luca.milanesio@gmail.com>Tue Feb 04 11:01:40 2020 +0000
committerLuca Milanesio <luca.milanesio@gmail.com>Tue Feb 04 11:01:40 2020 +0000
treeae710725f9641bba3f7eb63a4760131febd8e81c
parentebe784b8c825ef1a116945baae05f1e53aa8e4da [diff]
parentd5f2e1f02b3c91a993405ebeadc709270423f079 [diff]
Merge branch 'stable-2.16' into stable-3.0

* stable-2.16:
  Route cache evictions routing to CacheEvictionEventRouter

Change-Id: Ib9519810491be585f1302ac4d0361e91ee9c4a6a
tree: ae710725f9641bba3f7eb63a4760131febd8e81c
  1. .settings/
  2. dockerised_local_env/
  3. images/
  4. setup_local_env/
  5. src/
  6. .bazelrc
  7. .gitignore
  8. .mailmap
  9. BUILD
  10. DESIGN.md
  11. docker-compose.kafka-broker.yaml
  12. external_plugin_deps.bzl
  13. LICENSE
  14. 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.

Currently, the only mode supported is one primary read/write master and multiple read-only masters but eventually the plan is to support multiple read/write masters. The read/write master is handling any traffic while the read-only masters are serving the Gerrit GUI assets, the HTTP GET REST API and git fetch requests (git-upload-pack). The read-only masters are kept synchronized with the read/write master in order to be always ready to become a read/write master.

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 .
rm external_plugin_deps.bzl
ln -s multi-site/external_plugin_deps.bzl .

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.

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, for more details please refer to the replication plugin documentation.