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diff --git a/doc/administration/high_availability/redis.md b/doc/administration/high_availability/redis.md index f6153216f33..1adc681e98b 100644 --- a/doc/administration/high_availability/redis.md +++ b/doc/administration/high_availability/redis.md @@ -3,6 +3,113 @@ You can choose to install and manage Redis yourself, or you can use GitLab Omnibus packages to help. +## Experimental Redis Sentinel support + +Since 8.10 release, you can configure a list of Redis Sentinel servers that +will monitor a group of Redis servers to provide you with a standard failover +support. + +There is currently one exception to the Sentinel support: **mail_room**, the +component that process incoming emails. + +It doesn't support Sentinel yet, but we hope to integrate a future release +that does support it. + +To get a better understanding on how to correctly setup Sentinel, please read +[Redis Sentinel documentation](http://redis.io/topics/sentinel) first, as +faling to configure it correctly can lead to data-loss. + +### Redis setup + +You must have at least 2 Redis servers: 1 Master, 1 or more Slaves. +They should be configured the same way and with similar server specs, as +in a failover situation, any Slave can be elected as the new Master by +the Sentinels servers. + +In a minimal setup, the only required change for the slaves in `redis.conf` +is the addition of a `slaveof` line pointing to the initial master like this: + +```conf +slaveof 192.168.1.1 6379 +``` + +You can increase the security by defining a `requirepass` configuration in +the master: + +```conf +requirepass "<password> +``` + +and adding this line to all the slave servers: + +```conf +masterauth "<password>" +``` + +> **Note** This setup is not safe to be used by a machine accessible by the +internet. Use it in combination with tight firewall rules. + +### Sentinel setup + +The support for Sentinel in ruby have some [caveats](https://github.com/redis/redis-rb/issues/531). +While you can give any name for the `master-group-name` part of the +configuration, as in this example: + +```conf +sentinel monitor <master-group-name> <ip> <port> <quorum>` +``` + +For it to work in ruby, you have to use the "hostname" of the master redis +server otherwhise you will get an error message like this one: +`Redis::CannotConnectError: No sentinels available.`. + + +Here is an example configuration file (`sentinel.conf`) for a Sentinel node: + +```conf +port 26379 +sentinel monitor master-redis.example.com 10.10.10.10 6379 1 +sentinel down-after-milliseconds master-redis.example.com 10000 +sentinel config-epoch master-redis.example.com 0 +sentinel leader-epoch locmaster-redis.example.comalhost 0 +``` + +### GitLab setup + +You can enable or disable sentinel support at any time in new or existing +installs. From the GitLab application perspective, all it requires is +the correct credentials for the Master redis and for a few Sentinels nodes. + +It doesn't require a list of all sentinel nodes, as in case of a failure, +the application will need to query only one of them. + +For a source based install, you must change `/home/git/gitlab/config/resque.yml`, +following the example in `/home/git/gitlab/config/resque.yml.example` and +uncommenting the sentinels line, changing to the correct server credentials, +and resstart GitLab. + +For a Omnibus install you have to add/change this lines from the +`/etc/gitlab/gitlab.rb` configuration file: + +```ruby +gitlab['gitlab-rails']['redis_host'] = "master-redis.example.com" +gitlab['gitlab-rails']['redis_port'] = 6379 +gitlab['gitlab-rails']['redis_password'] = "redis-secure-password-here" +gitlab['gitlab-rails']['redis_socket'] = nil +gitlab['gitlab-rails']['redis_sentinels'] = [ + {'host' => '10.10.10.1', 'port' => 26379}, + {'host' => '10.10.10.2', 'port' => 26379}, + {'host' => '10.10.10.3', 'port' => 26379} +] +``` + +After the change run the reconfigure command: + +```bash +sudo gitlab-ctl reconfigure + +``` + ## Configure your own Redis server If you're hosting GitLab on a cloud provider, you can optionally use a |