# GitLab Geo database replication This document describes the minimal steps you have to take in order to replicate your GitLab database into another server. You may have to change some values according to your database setup, how big it is, etc. The GitLab primary node where the write operations happen will act as `master`, and the secondary ones which are read-only will act as `slaves`. >**Note:** To be on par with GitLab's notation, we will use `primary` to denote the `master` server, and `secondary` for the `slave`. <!-- 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** *generated with [DocToc](https://github.com/thlorenz/doctoc)* - [PostgreSQL replication](#postgresql-replication) - [PostgreSQL - Configure the primary server](#postgresql-configure-the-primary-server) - [PostgreSQL - Configure the secondary server](#postgresql-configure-the-secondary-server) - [PostgreSQL - Initiate the replication process](#postgresql-initiate-the-replication-process) - [MySQL replication](#mysql-replication) <!-- END doctoc generated TOC please keep comment here to allow auto update --> ## PostgreSQL replication The following guide assumes that: - You are using PostgreSQL 9.1 or later which includes the [`pg_basebackup` tool][pgback]. As of this writing, the latest Omnibus packages (8.5) have version 9.2. - You have a primary server already set up, running PostgreSQL 9.2.x, and you have a new secondary server set up on the same OS and PostgreSQL version. If you are using Omnibus, make sure the GitLab version is the same on all nodes. - The IP of the primary server for our examples will be `1.2.3.4`, whereas the secondary's IP will be `5.6.7.8`. [pgback]: http://www.postgresql.org/docs/9.2/static/app-pgbasebackup.html ### PostgreSQL - Configure the primary server **For installations from source** 1. Login as root and create a replication user: ```bash sudo -u postgres psql -c "CREATE USER gitlab_replicator REPLICATION ENCRYPTED PASSWORD 'thepassword';" ``` 1. Edit `postgresql.conf` to configure the primary server for streaming replication (for Debian/Ubuntu that would be `/etc/postgresql/9.2/main/postgresql.conf`): ```bash listen_address = '1.2.3.4' wal_level = hot_standby max_wal_senders = 5 checkpoint_segments = 10 wal_keep_segments = 10 hot_standby = on ``` Edit the `wal` values as you see fit. 1. Set the access control on the primary to allow TCP connections using the server's public IP and set the connection from the secondary to require a password. Edit `pg_hba.conf` (for Debian/Ubuntu that would be `/etc/postgresql/9.2/main/pg_hba.conf`): ```bash host all all 127.0.0.1/32 trust host all all 1.2.3.4/32 trust host replication gitlab_replicator 5.6.7.8/32 md5 ``` Where `1.2.3.4` is the public IP address of the primary server, and `5.6.7.8` the public IP address of the secondary one. 1. Restart PostgreSQL for the changes to take effect --- **For Omnibus installations** 1. Omnibus GitLab has already a replicator user called `gitlab_replicator`. You must set its password manually: ```bash sudo -u gitlab-psql /opt/gitlab/embedded/bin/psql -h /var/opt/gitlab/postgresql \ -d template1 \ -c "ALTER USER gitlab_replicator WITH ENCRYPTED PASSWORD 'thepassword'" ``` 1. Edit `/etc/gitlab/gitlab.rb` and add the following: ```ruby postgresql['listen_address'] = "1.2.3.4" postgresql['trust_auth_cidr_addresses'] = ['127.0.0.1/32','1.2.3.4/32'] postgresql['md5_auth_cidr_addresses'] = ['5.6.7.8/32'] postgresql['sql_replication_user'] = "gitlab_replicator" postgresql['wal_level'] = "hot_standby" postgresql['max_wal_senders'] = 10 postgresql['wal_keep_segments'] = 10 postgresql['hot_standby'] = "on" ``` Where `1.2.3.4` is the public IP address of the primary server, and `5.6.7.8` the public IP address of the secondary one. Edit the `wal` values as you see fit. 1. [Reconfigure GitLab][] for the changes to take effect. --- Now that the PostgreSQL server is set up to accept remote connections, run `netstat -plnt` to make sure that PostgreSQL is listening to the server's public IP. Test that the remote connection works by going to the secondary server and running: ``` # For Omnibus installations sudo -u gitlab-psql /opt/gitlab/embedded/bin/psql -h 1.2.3.4 -U gitlab_replicator -d gitlabhq_production -W # For source installations sudo -u postgres psql -h 1.2.3.4 -U gitlab_replicator -d gitlabhq_production -W ``` When prompted enter the password you set in the first step for the `gitlab_replicator` user. If all worked correctly, you should see the database prompt. ### PostgreSQL - Configure the secondary server **For installations from source** 1. Edit `postgresql.conf` to configure the secondary for streaming replication (for Debian/Ubuntu that would be `/etc/postgresql/9.2/main/postgresql.conf`): ```bash wal_level = hot_standby max_wal_senders = 5 checkpoint_segments = 10 wal_keep_segments = 10 hot_standby = on ``` 1. Restart PostgreSQL for the changes to take effect --- **For Omnibus installations** 1. Edit `/etc/gitlab/gitlab.rb` and add the following: ```ruby postgresql['wal_level'] = "hot_standby" postgresql['max_wal_senders'] = 10 postgresql['wal_keep_segments'] = 10 postgresql['hot_standby'] = "on" ``` 1. [Reconfigure GitLab][] for the changes to take effect. ### PostgreSQL - Initiate the replication process Below we provide a script that connects to the primary server, replicates the database and creates the needed files for replication. The directories used are the defaults that are set up in Omnibus. Configure it as you see fit replacing the directories and paths. >**Warning:** Make sure to run this on the _**secondary**_ server as it removes all PostgreSQL's data before running `pg_basebackup`. ```bash #!/bin/bash PORT="5432" USER="gitlab_replicator" echo Enter ip of primary postgresql server read HOST echo Enter password for $USER@$HOST read -s PASSWORD echo Stopping PostgreSQL gitlab-ctl stop echo Backup postgresql.conf sudo -u gitlab-psql mv /var/opt/gitlab/postgresql/data/postgresql.conf /var/opt/gitlab/postgresql/ echo Cleaning up old cluster directory sudo -u gitlab-psql rm -rf /var/opt/gitlab/postgresql/data rm -f /tmp/postgresql.trigger echo Starting base backup as replicator echo Enter password for $USER@$HOST sudo -u gitlab-psql /opt/gitlab/embedded/bin/pg_basebackup -h $HOST -D /var/opt/gitlab/postgresql/data -U gitlab_replicator -v -x -P echo Writing recovery.conf file sudo -u gitlab-psql bash -c "cat > /var/opt/gitlab/postgresql/data/recovery.conf <<- _EOF1_ standby_mode = 'on' primary_conninfo = 'host=$HOST port=$PORT user=$USER password=$PASSWORD' trigger_file = '/tmp/postgresql.trigger' _EOF1_ " echo Restore postgresql.conf sudo -u gitlab-psql mv /var/opt/gitlab/postgresql/postgresql.conf /var/opt/gitlab/postgresql/data/ echo Starting PostgreSQL gitlab-ctl start ``` When prompted, enter the password you set up for the `gitlab_replicator` user. ## MySQL replication TODO [reconfigure gitlab]: ../restart_gitlab.md#omnibus-gitlab-reconfigure