commit	d2cbd124105b7de699b837c66fc7375cfc85ac87	[log] [tgz]
author	Luca Milanesio <luca.milanesio@gmail.com>	Thu Apr 25 17:57:25 2019 +0100
committer	Luca Milanesio <luca.milanesio@gmail.com>	Wed May 01 22:52:11 2019 +0000
tree	8fbfde24e9fc4f40e24baeb6fba97b7fe00f2489
parent	3c818c067bfd0fbf05e2cdfbe89db1dc0198ee81 [diff]

Use pre-defined Gerrit EventGsonProvider

The current master of Gerrit heading to v3.1 has introduced auto-values
for many of the basic key objects, ranging from project keys, to user ids,
groups uuids and change ids.

Currently, only Change.Key is used in event classes and it is correctly
managed by the pre-defined EventGsonProvider. The stream events JSON
format is slightly different because of the adoption of the same
ProjectNameKeyAdapter used for current Gerrit stream events serialization.

With regards to the other keys, they are used only in cache evictions
and are individually custom deserialized because they are composed by
a single field.

Moving forward, Gerrit should start introducing the automatic support
for AutoValue deserialization for all types; the custom de-serialization
of keys will then be removed and the EventGsonProvider will be used
across the board.

Change-Id: I279879daee8f12ce49ef6bc49f451d4f0726923f

32 files changed

tree: 8fbfde24e9fc4f40e24baeb6fba97b7fe00f2489

README.md

Gerrit multi-site plugin

This plugin allows having multiple Gerrit masters to be deployed across various sites without having to share any storage. The alignment between the masters happens using the replication plugin and an external message broker.

The Gerrit masters requirements are:

Gerrit v2.16.5 or later
Migrated to NoteDb
Connected to the same message broker
Accessible behind 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 N 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 the git-upload-packs. The read-only masters are kept updated 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 is built like any other Gerrit plugin 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-genfiles/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.

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

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

Create the $GERRIT_SITE/etc/multi-site.config on all Gerrit servers with the following basic settings:

[kafka]
  bootstrapServers = <kafka-host>:<kafka-port>

[kafka "publisher"]
  enabled = true

[kafka "subscriber"]
  enabled = true

[ref-database]
  enabled = true

[ref-database "zookeeper"]
  connectString = "localhost:2181"

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

You need also to setup the Git-level replication between nodes, for more details please refer to the replication plugin documentation.