|author||Fabio Ponciroli <email@example.com>||Tue Mar 03 15:16:08 2020 +0100|
|committer||Luca Milanesio <firstname.lastname@example.org>||Thu Mar 05 13:30:23 2020 +0000|
Reload local version when in memory ref is not up to date When multiple updates are replication events might pile up and the ref carried in the RemoteRefUpdate event might be behind the one locally stored. This will lead to filter out some replication events. The situation is restored as soon as a new replication will be triggered. The repository will be out of sync until the arrival of the next replication. Read the local ref and re-try the comparison to mitigate the issue. Bug: Issue 12425 Change-Id: I579f277635eff5d5cdd1d71a090fe06f2be22c0f
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:
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
This plugin is released under the same Apache 2.0 license and copyright holders as of the Gerrit Code Review project.
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
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.
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
Add the multi-site module to
$GERRIT_SITE/etc/gerrit.config as follows:
[gerrit] installModule = com.googlesource.gerrit.plugins.multisite.Module
$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 also need to setup the Git-level replication between nodes, for more details please refer to the replication plugin documentation.