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Diffstat (limited to 'doc/administration/database_load_balancing.md')
| -rw-r--r-- | doc/administration/database_load_balancing.md | 45 |
1 files changed, 16 insertions, 29 deletions
diff --git a/doc/administration/database_load_balancing.md b/doc/administration/database_load_balancing.md index e9f989c96ea..7d17b22a4d7 100644 --- a/doc/administration/database_load_balancing.md +++ b/doc/administration/database_load_balancing.md @@ -31,7 +31,7 @@ sent to the primary (unless necessary), the primary (`db3`) hardly has any load. ## Requirements -For load balancing to work you will need at least PostgreSQL 11 or newer, +For load balancing to work, you need at least PostgreSQL 11 or newer, [**MySQL is not supported**](../install/requirements.md#database). You also need to make sure that you have at least 1 secondary in [hot standby](https://www.postgresql.org/docs/11/hot-standby.html) mode. @@ -42,7 +42,7 @@ you should put a load balancer in front of every database, and have GitLab conne to those load balancers. For example, say you have a primary (`db1.gitlab.com`) and two secondaries, -`db2.gitlab.com` and `db3.gitlab.com`. For this setup you will need to have 3 +`db2.gitlab.com` and `db3.gitlab.com`. For this setup, you need to have 3 load balancers, one for every host. For example: - `primary.gitlab.com` forwards to `db1.gitlab.com` @@ -56,7 +56,7 @@ means forwarding should now happen as follows: - `secondary1.gitlab.com` forwards to `db1.gitlab.com` - `secondary2.gitlab.com` forwards to `db3.gitlab.com` -GitLab does not take care of this for you, so you will need to do so yourself. +GitLab does not take care of this for you, so you need to do so yourself. Finally, load balancing requires that GitLab can connect to all hosts using the same credentials and port as configured in the @@ -72,7 +72,7 @@ different ports or credentials for different hosts is not supported. ## Enabling load balancing For the environment in which you want to use load balancing, you'll need to add -the following. This will balance the load between `host1.example.com` and +the following. This balances the load between `host1.example.com` and `host2.example.com`. **In Omnibus installations:** @@ -104,32 +104,19 @@ the following. This will balance the load between `host1.example.com` and 1. Save the file and [restart GitLab](restart_gitlab.md#installations-from-source) for the changes to take effect. -### Enable the load balancer for Sidekiq +### Load balancing for Sidekiq -Sidekiq mostly writes to the database, which means that most of its traffic hits the -primary database. +> [Introduced](https://gitlab.com/gitlab-org/gitlab/-/issues/334494) in GitLab 14.1, load balancing for Sidekick is enabled by default. -Some background jobs can use database replicas to read application state. +Sidekiq jobs mostly write to the primary database, but there are read-only jobs that can benefit +from the use of Sidekiq load balancing. +These jobs can use load balancing and database replicas to read the application state. This allows to offload the primary database. -Load balancing is disabled by default in Sidekiq. When enabled, we can define -[the data consistency](../development/sidekiq_style_guide.md#job-data-consistency-strategies) +For Sidekiq, we can define +[data consistency](../development/sidekiq_style_guide.md#job-data-consistency-strategies) requirements for a specific job. -To enable it, define the `ENABLE_LOAD_BALANCING_FOR_SIDEKIQ` variable to the environment, as shown below. - -For Omnibus installations: - -```ruby -gitlab_rails['env'] = {"ENABLE_LOAD_BALANCING_FOR_SIDEKIQ" => "true"} -``` - -For installations from source: - -```shell -export ENABLE_LOAD_BALANCING_FOR_SIDEKIQ="true" -``` - ## Service Discovery > [Introduced](https://gitlab.com/gitlab-org/gitlab/-/merge_requests/5883) in [GitLab Premium](https://about.gitlab.com/pricing/) 11.0. @@ -176,15 +163,15 @@ The following options can be set: | `disconnect_timeout` | The time in seconds after which an old connection is closed, after the list of hosts was updated. | 120 | | `use_tcp` | Lookup DNS resources using TCP instead of UDP | false | -If `record_type` is set to `SRV`, GitLab will continue to use a round-robin algorithm -and will ignore the `weight` and `priority` in the record. Since SRV records usually -return hostnames instead of IPs, GitLab will look for the IPs of returned hostnames +If `record_type` is set to `SRV`, then GitLab continues to use round-robin algorithm +and ignores the `weight` and `priority` in the record. Since SRV records usually +return hostnames instead of IPs, GitLab needs to look for the IPs of returned hostnames in the additional section of the SRV response. If no IP is found for a hostname, GitLab -will query the configured `nameserver` for ANY record for each such hostname looking for A or AAAA +needs to query the configured `nameserver` for ANY record for each such hostname looking for A or AAAA records, eventually dropping this hostname from rotation if it can't resolve its IP. The `interval` value specifies the _minimum_ time between checks. If the A -record has a TTL greater than this value, then service discovery will honor said +record has a TTL greater than this value, then service discovery honors said TTL. For example, if the TTL of the A record is 90 seconds, then service discovery waits at least 90 seconds before checking the A record again. |