Configuring GitLab for HA

Assuming you have already configured a database, Redis, and NFS, you can configure the GitLab application server(s) now. Complete the steps below for each GitLab application server in your environment.

Note: There is some additional configuration near the bottom for additional GitLab application servers. It's important to read and understand these additional steps before proceeding with GitLab installation.

If necessary, install the NFS client utility packages using the following commands:

# Ubuntu/Debian
apt-get install nfs-common

# CentOS/Red Hat
yum install nfs-utils nfs-utils-lib

Specify the necessary NFS shares. Mounts are specified in /etc/fstab. The exact contents of /etc/fstab will depend on how you chose to configure your NFS server. See NFS documentation for the various options. Here is an example snippet to add to /etc/fstab:

10.1.0.1:/var/opt/gitlab/.ssh /var/opt/gitlab/.ssh nfs defaults,soft,rsize=1048576,wsize=1048576,noatime,nofail,lookupcache=positive 0 2
10.1.0.1:/var/opt/gitlab/gitlab-rails/uploads /var/opt/gitlab/gitlab-rails/uploads nfs defaults,soft,rsize=1048576,wsize=1048576,noatime,nofail,lookupcache=positive 0 2
10.1.0.1:/var/opt/gitlab/gitlab-rails/shared /var/opt/gitlab/gitlab-rails/shared nfs defaults,soft,rsize=1048576,wsize=1048576,noatime,nofail,lookupcache=positive 0 2
10.1.0.1:/var/opt/gitlab/gitlab-ci/builds /var/opt/gitlab/gitlab-ci/builds nfs defaults,soft,rsize=1048576,wsize=1048576,noatime,nofail,lookupcache=positive 0 2
10.1.0.1:/var/opt/gitlab/git-data /var/opt/gitlab/git-data nfs defaults,soft,rsize=1048576,wsize=1048576,noatime,nofail,lookupcache=positive 0 2

Create the shared directories. These may be different depending on your NFS mount locations.

mkdir -p /var/opt/gitlab/.ssh /var/opt/gitlab/gitlab-rails/uploads /var/opt/gitlab/gitlab-rails/shared /var/opt/gitlab/gitlab-ci/builds /var/opt/gitlab/git-data

Download/install GitLab Omnibus using steps 1 and 2 from GitLab downloads. Do not complete other steps on the download page.
Create/edit /etc/gitlab/gitlab.rb and use the following configuration. Be sure to change the external_url to match your eventual GitLab front-end URL. Depending your the NFS configuration, you may need to change some GitLab data locations. See NFS documentation for /etc/gitlab/gitlab.rb configuration values for various scenarios. The example below assumes you've added NFS mounts in the default data locations. Additionally the UID and GIDs given are just examples and you should configure with your preferred values.
```
external_url 'https://gitlab.example.com'

# Prevent GitLab from starting if NFS data mounts are not available
high_availability['mountpoint'] = '/var/opt/gitlab/git-data'

# Disable components that will not be on the GitLab application server
roles ['application_role']

# PostgreSQL connection details
gitlab_rails['db_adapter'] = 'postgresql'
gitlab_rails['db_encoding'] = 'unicode'
gitlab_rails['db_host'] = '10.1.0.5' # IP/hostname of database server
gitlab_rails['db_password'] = 'DB password'

# Redis connection details
gitlab_rails['redis_port'] = '6379'
gitlab_rails['redis_host'] = '10.1.0.6' # IP/hostname of Redis server
gitlab_rails['redis_password'] = 'Redis Password'

# Ensure UIDs and GIDs match between servers for permissions via NFS
user['uid'] = 9000
user['gid'] = 9000
web_server['uid'] = 9001
web_server['gid'] = 9001
registry['uid'] = 9002
registry['gid'] = 9002
```
Note: To maintain uniformity of links across HA clusters, the external_url on the first application server as well as the additional application servers should point to the external url that users will use to access GitLab. In a typical HA setup, this will be the url of the load balancer which will route traffic to all GitLab application servers in the HA cluster.

Note: When you specify https in the external_url, as in the example above, GitLab assumes you have SSL certificates in /etc/gitlab/ssl/. If certificates are not present, Nginx will fail to start. See Nginx documentation for more information.

First GitLab application server

As a final step, run the setup rake task only on the first GitLab application server. Do not run this on additional application servers.

Initialize the database by running sudo gitlab-rake gitlab:setup.
Run sudo gitlab-ctl reconfigure to compile the configuration.

WARNING: Only run this setup task on NEW GitLab instances because it will wipe any existing data.

Extra configuration for additional GitLab application servers

Additional GitLab servers (servers configured after the first GitLab server) need some extra configuration.

Configure shared secrets. These values can be obtained from the primary GitLab server in /etc/gitlab/gitlab-secrets.json. Add these to /etc/gitlab/gitlab.rb prior to running the first reconfigure.

gitlab_shell['secret_token'] = 'fbfb19c355066a9afb030992231c4a363357f77345edd0f2e772359e5be59b02538e1fa6cae8f93f7d23355341cea2b93600dab6d6c3edcdced558fc6d739860'
gitlab_rails['otp_key_base'] = 'b719fe119132c7810908bba18315259ed12888d4f5ee5430c42a776d840a396799b0a5ef0a801348c8a357f07aa72bbd58e25a84b8f247a25c72f539c7a6c5fa'
gitlab_rails['secret_key_base'] = '6e657410d57c71b4fc3ed0d694e7842b1895a8b401d812c17fe61caf95b48a6d703cb53c112bc01ebd197a85da81b18e29682040e99b4f26594772a4a2c98c6d'
gitlab_rails['db_key_base'] = 'bf2e47b68d6cafaef1d767e628b619365becf27571e10f196f98dc85e7771042b9203199d39aff91fcb6837c8ed83f2a912b278da50999bb11a2fbc0fba52964'

Run touch /etc/gitlab/skip-auto-migrations to prevent database migrations from running on upgrade. Only the primary GitLab application server should handle migrations.
Optional Configure host keys. Copy all contents(primary and public keys) inside /etc/ssh/ on the primary application server to /etc/ssh on all secondary servers. This prevents false man-in-the-middle-attack alerts when accessing servers in your High Availability cluster behind a load balancer.
Run sudo gitlab-ctl reconfigure to compile the configuration.

Troubleshooting

mount: wrong fs type, bad option, bad superblock on

You have not installed the necessary NFS client utilities. See step 1 above.

mount: mount point /var/opt/gitlab/... does not exist

This particular directory does not exist on the NFS server. Ensure the share is exported and exists on the NFS server and try to remount.

Read more on high-availability configuration: