| commit | c96f041041dffb7ecb79399610dacfb7daf4104e | [log] [tgz] |
|---|---|---|
| author | Luca Milanesio <luca.milanesio@gmail.com> | Wed Dec 13 22:58:42 2023 +0000 |
| committer | Luca Milanesio <luca.milanesio@gmail.com> | Wed Dec 20 18:55:40 2023 +0000 |
| tree | ae341e96d287d9acf31960985067d06742be2fcf | |
| parent | 49b4eb8c39d2f326a2e10b9938bb43f78cb74db3 [diff] |
Update the refs/multi-site/version/value once per batch-refupdate The update of refs/multi-site/version/value on the global-refdb is a very expensive operation for two reasons: - The global-refdb is a remote system, potentially with a high network latency - It needs to maintain global consistency across geographical areas which would also include sever-side synchronisation Reducing the number of updates on the global-refdb is paramount for keeping an acceptable performance in Gerrit updates. When multiple updates happen in the same batch for Gerrit, it would not make sense to update the global-refdb multiple times for the version value because globally the batch represents a unit of work and performing it as a whole means updating the version of the repository once. Move from individual stream-events to batch ref-update listener for updating the refs/multi-site/version/value, so that multiple updates would result in a single global-refdb update. Note that the batch ref-update listener is not a stream event and therefore the code does not need to check and test the instance-id anymore because all the events received are always local. For example, the upload of a new patch-set for a change was previously generating four different updates on the global-refdb for the refs/multi-site/version/value, whilst now there is only one single update generated for the whole batch. Change-Id: Ia6c7f5aa085a8e2770b40df34145bb937cf1772e
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.
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
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 .
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.
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
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.
For information about available HTTP endpoints please refer to the documentation.