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author | Achilleas Pipinellis <axilleas@axilleas.me> | 2016-11-10 15:51:13 +0100 |
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committer | Achilleas Pipinellis <axilleas@axilleas.me> | 2016-11-10 15:51:13 +0100 |
commit | fb0dff6ea848f58a068030f93e8728ce0143c592 (patch) | |
tree | 46810e7140f79370f7f7b88979ad0d503f73ccf6 | |
parent | c43b540095b6de03e679dc4dd56df97f08a6aed0 (diff) | |
download | gitlab-ce-fb0dff6ea848f58a068030f93e8728ce0143c592.tar.gz |
Move some things over
-rw-r--r-- | doc/administration/high_availability/redis.md | 195 |
1 files changed, 112 insertions, 83 deletions
diff --git a/doc/administration/high_availability/redis.md b/doc/administration/high_availability/redis.md index 3837a8a0a88..5d4dfe22779 100644 --- a/doc/administration/high_availability/redis.md +++ b/doc/administration/high_availability/redis.md @@ -1,73 +1,105 @@ # Configuring Redis for GitLab HA -High Availability with Redis is possible using a **Master** x **Slave** -topology with **Sentinel** service to watch and automatically start -failover proceedings. +High Availability with [Redis] is possible using a **Master** x **Slave** +topology with a [Redis Sentinel][sentinel] service to watch and automatically +start failover proceedings. You can choose to install and manage Redis and Sentinel yourself, use -a hosted, managed cloud solution or you can use or you can use the one -that comes bundled with Omnibus GitLab packages. +a hosted cloud solution or you can use the one that comes bundled with +Omnibus GitLab packages. -> **Note:** Redis requires authentication for High Availability. See +> **Notes:** +- Redis requires authentication for High Availability. See [Redis Security](http://redis.io/topics/security) documentation for more information. We recommend using a combination of a Redis password and tight firewall rules to secure your Redis service. +- You are highly encouraged to read the [Redis Sentinel][sentinel] documentation + before configuring Redis HA with GitLab to fully understand the topology and + architecture. <!-- START doctoc generated TOC please keep comment here to allow auto update --> <!-- DON'T EDIT THIS SECTION, INSTEAD RE-RUN doctoc TO UPDATE --> **Table of Contents** -- [Using an external Redis server](#using-an-external-redis-server) -- [High Availability with Sentinel](#high-availability-with-sentinel) - - [Prerequisites](#prerequisites) - - [Redis setup](#redis-setup) - - [Sentinel setup](#sentinel-setup) - - [Recommended setup](#recommended-setup) +- [Overview](#overview) + - [Available setups](#available-setups) + - [Using a non-Omnibus external Redis server](#using-a-non-omnibus-external-redis-server) + - [High Availability with Sentinel](#high-availability-with-sentinel) + - [Prerequisites](#prerequisites) + - [Recommended setup](#recommended-setup) +- [Redis HA configuration](#redis-ha-configuration) + - [Redis setup](#redis-setup) + - [Sentinel setup](#sentinel-setup) - [Configuring instances using Omnibus](#configuring-instances-using-omnibus) - - [Existing single-machine installation](#existing-single-machine-installation) - - [Configuring Master Redis instance](#configuring-master-redis-instance) - - [Configuring Slave Redis instances](#configuring-slave-redis-instances) - - [Configuring Sentinel instances](#configuring-sentinel-instances) - - [Community Edition](#community-edition) - - [Enterprise Edition](#enterprise-edition) - - [GitLab setup](#gitlab-setup) -- [Example Configurations](#example-configurations) - - [Configuration for Redis Master](#configuration-for-redis-master) - - [Configuration for Redis Slave](#configuration-for-redis-slave) - - [Configuration for Sentinel (EE only)](#configuration-for-sentinel-ee-only) - - [Control running services](#control-running-services) + - [Existing single-machine installation](#existing-single-machine-installation) + - [Configuring Master Redis instance](#configuring-master-redis-instance) + - [Configuring Slave Redis instances](#configuring-slave-redis-instances) + - [Configuring Sentinel instances](#configuring-sentinel-instances) + - [Community Edition](#community-edition) + - [Enterprise Edition](#enterprise-edition) + - [GitLab setup](#gitlab-setup) +- [Minimal example configuration with 1 master, 2 slaves and 3 sentinels](#minimal-example-configuration-with-1-master-2-slaves-and-3-sentinels) + - [Configuration for Redis Master](#configuration-for-redis-master) + - [Configuration for Redis Slave](#configuration-for-redis-slave) + - [Configuration for Sentinel (EE only)](#configuration-for-sentinel-ee-only) + - [Control running services](#control-running-services) - [Troubleshooting](#troubleshooting) - - [Redis replication](#redis-replication) - - [Sentinel](#sentinel) - - [Omnibus GitLab](#omnibus-gitlab) + - [Redis replication](#redis-replication) + - [Sentinel](#sentinel) + - [Omnibus GitLab](#omnibus-gitlab) - [Changelog](#changelog) - - [Experimental Redis Sentinel support](#experimental-redis-sentinel-support) + - [Experimental Redis Sentinel support](#experimental-redis-sentinel-support) <!-- END doctoc generated TOC please keep comment here to allow auto update --> -## Using an external Redis server + +## Overview + +Before diving into the details of setting up Redis and Redis Sentinel for HA, +make sure you read this section to better understand the underline architecture. + +### Available setups + +Based on your infrastructure setup, there are multiple ways to setup Redis HA +with GitLab. Omnibus GitLab packages have Redis and Redis Sentinel bundled with +them to save you the hassle to install it yourself. Pick the one that suits your +needs. + +- **Installations from source:** You need to install Redis and Redis Sentinel + yourself. Use the [Redis HA source install](redis_source.md) guide. +- **Omnibus Community Edition (CE):** Redis is bundled so you can use the + package with only the Redis service enabled (works for both master and slave + setups). +- **Omnibus Enterprise Edition (EE):** Both Redis and Redis Sentinel are bundled + in the Omnibus package so you can use only them to setup the whole Redis HA + infrastructure (master, slave and Sentinel). + +Note that with the Omnibus packages (both CE and EE), you can also use an +[external Redis server](#using-a-non-omnibus-external-redis-server). + +### Using a non-Omnibus external Redis server If you're hosting GitLab on a cloud provider, you can optionally use a managed service for Redis. For example, AWS offers a managed ElastiCache service that runs Redis. Managed services can provide High Availability using their own proprietary -technology and provide a transparent proxy, which means that GitLab doesn't -need any additional change, or will use Sentinel and manage it for you. +technology and provide a transparent proxy (which means that GitLab doesn't +need any additional change) or they will use Sentinel and manage it for you. -If your provider, uses Sentinel method, see [GitLab Setup](#gitlab-setup) +If your provider, uses Sentinel, see [GitLab Setup](#gitlab-setup) to understand where you need to provide the list of servers and credentials. If you want to setup Redis by yourself, without using Omnibus, you can -read our documentation: [Configuring Redis for GitLab HA (source install)](redis_source.md). - -## High Availability with Sentinel +read the documentation on [configuring Redis HA for source installs](redis_source.md). -> Since GitLab `8.11`, you can configure a list of Redis Sentinel servers that -will monitor a group of Redis servers to provide failover support. +### High Availability with Sentinel -> With GitLab `8.14`, we bundled Redis Sentinel as part of Omnibus package and -improved the way you use and configure it. +> +- Since GitLab `8.11`, you can configure a list of Redis Sentinel servers that + will monitor a group of Redis servers to provide failover support. +- With GitLab `8.14`, we bundled Redis Sentinel as part of Omnibus package and + improved the way you use and configure it. High Availability with Redis requires a few things: @@ -77,12 +109,12 @@ High Availability with Redis requires a few things: - Application support and visibility to all Sentinel and Redis instances Redis Sentinel can handle the most important tasks in a HA environment to help -keep servers online with minimal to no downtime: +keep servers online with minimal to no downtime. Redis Sentinel: - Monitors **Master** and **Slaves** instances to see if they are available -- Promote a **Slave** to **Master** when the **Master** fails -- Demote a **Master** to **Slave** when failed **Master** comes back online (to prevent - data-partitioning) +- Promotes a **Slave** to **Master** when the **Master** fails +- Demotes a **Master** to **Slave** when failed **Master** comes back online + (to prevent data-partitioning) - Can be queried by clients to always connect to the current **Master** server When a **Master** fails to respond, it's the client's responsibility to handle @@ -93,24 +125,16 @@ the [Redis Sentinel documentation](http://redis.io/topics/sentinel) first, as failing to configure it correctly can lead to data loss, or can bring your whole cluster down, invalidating the failover effort. -This documentation will provide you with a minimal and a recommended topology -that can resist to some levels of failure. Usually the more Redis and Sentinel -instances you have provisioned, the better will be your availability. - -The configuration consists of three parts: - -- Setup Redis Master and Slave nodes -- Setup Sentinel nodes -- Setup GitLab - ### Prerequisites You need at least `3` independent machines: physical, or VMs running into -distinct physical machines. They must be believed to fail in an -independent way. +distinct physical machines. It is essential that all master and Redis slaves +run in different machines. If you fail to provision the machines in that +specific way, any issue with the shared environment can bring your entire setup +down. -If you fail to provision the machines in that specific way, any issue with -the shared environment can bring your entire setup down. +It is OK to run a Sentinel along with a master or slave Redis instance. +No more than one though. You also need to take in consideration the underlying network topology, making sure you have redundant connectivity between Redis / Sentinel and @@ -119,6 +143,30 @@ failure. Read carefully how to configure the components below. +### Recommended setup + +For a minimal setup, you will install the Omnibus GitLab package in `3` +independent machines, both with **Redis** and **Sentinel**: + +- Redis Master + Sentinel +- Redis Slave + Sentinel +- Redis Slave + Sentinel + +Make sure you've read [Redis Setup](#redis-setup) and [Sentinel Setup](#sentinel-setup) +before, to understand how and why the amount of nodes came from. + +For a recommended setup, that can resist more failures, you will install +the Omnibus GitLab package in `5` independent machines, both with +**Redis** and **Sentinel**: + +- Redis Master + Sentinel +- Redis Slave + Sentinel +- Redis Slave + Sentinel +- Redis Slave + Sentinel +- Redis Slave + Sentinel + +## Redis HA configuration + ### Redis setup You must have at least `3` Redis servers: `1` Master, `2` Slaves, and they @@ -156,14 +204,14 @@ Initial **Slave** nodes requires `redis['master']` defined to `false` and simplified configuration by enabling `redis_slave_role['enable']`, you just need to fill in the `redis['master_ip']`. -This values doesn't have to be changed again in `/etc/gitlab/gitlab.rb` after +This values don't have to be changed again in `/etc/gitlab/gitlab.rb` after a failover, as the nodes will be managed by the Sentinels, and even after a `gitlab-ctl reconfigure`, they will get their configuration restored by the same Sentinels. ### Sentinel setup -Sentinels watches both other sentinels and Redis nodes. Whenever a Sentinel +Sentinels watch both other sentinels and Redis nodes. Whenever a Sentinel detects that a Redis node is not responding, it will announce that to the other sentinels. You have to reach the **quorum**, the minimum amount of sentinels that agrees that a node is down, to be able to start a failover. @@ -222,33 +270,12 @@ official documentation: the slaves will be reconfigured by the Sentinels anyway, but not with the exact parallel-syncs progression as specified. -### Recommended setup - -For a minimal setup, you will install the Omnibus GitLab package in `3` -independent machines, both with **Redis** and **Sentinel**: - -- Redis Master + Sentinel -- Redis Slave + Sentinel -- Redis Slave + Sentinel - -Make sure you've read [Redis Setup](#redis-setup) and [Sentinel Setup](#sentinel-setup) -before, to understand how and why the amount of nodes came from. - -For a recommended setup, that can resist more failures, you will install -the Omnibus GitLab package in `5` independent machines, both with -**Redis** and **Sentinel**: - -- Redis Master + Sentinel -- Redis Slave + Sentinel -- Redis Slave + Sentinel -- Redis Slave + Sentinel -- Redis Slave + Sentinel - ## Configuring instances using Omnibus This is a summary of what are we going to do: 1. Provision the required number of instances specified previously + - You can opt to install Redis and Sentinel in the same machine or each in independent ones. - Don't install Redis and Sentinel in the same machines your GitLab instance @@ -257,7 +284,7 @@ This is a summary of what are we going to do: connection over Redis (`6379`) and Sentinel (`26379`) ports. - GitLab machines must be able to access these machines and with the same permissions. - - Protected them from indiscriminating access from external networks (Internet), + - Protect them from access from external networks (Internet), to harden the security. 1. Download/install Omnibus GitLab using **steps 1 and 2** from @@ -394,7 +421,7 @@ which ideally should not have Redis or Sentinels in the same machine for a HA se See [example configuration](#configuration-for-gitlab) below. -## Example Configurations +## Minimal example configuration with 1 master, 2 slaves and 3 sentinels In this example we consider that all servers have an internal network interface with IPs in the `10.0.0.x` range, and that they can connect @@ -836,3 +863,5 @@ Read more on high-availability configuration: [reconfigure]: ../restart_gitlab.md#omnibus-gitlab-reconfigure [gh-531]: https://github.com/redis/redis-rb/issues/531 [gh-534]: https://github.com/redis/redis-rb/issues/534 +[redis]: http://redis.io/ +[sentinel]: http://redis.io/topics/sentinel |