# Configuring GitLab Scaling and High Availability > **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. 1. 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 ``` 1. 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](nfs.md) 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 nfs4 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 nfs4 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 nfs4 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 nfs4 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 nfs4 defaults,soft,rsize=1048576,wsize=1048576,noatime,nofail,lookupcache=positive 0 2 ``` 1. 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 ``` 1. Download/install GitLab Omnibus using **steps 1 and 2** from [GitLab downloads](https://about.gitlab.com/downloads). Do not complete other steps on the download page. 1. 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](nfs.md) 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. ```ruby 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'] nginx['enable'] = true # 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 ``` 1. [Enable monitoring](#enable-monitoring) > **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](http://docs.gitlab.com/omnibus/settings/nginx.html#enable-https) for more information. > > **Note:** It is best to set the `uid` and `gid`s prior to the initial reconfigure of GitLab. Omnibus will not recursively `chown` directories if set after the initial reconfigure. ## 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. 1. Initialize the database by running `sudo gitlab-rake gitlab:setup`. 1. 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. 1. Configure shared secrets. These values can be obtained from the primary GitLab server in `/etc/gitlab/gitlab-secrets.json`. Copy this file to the secondary servers **prior to** running the first `reconfigure` in the steps above. ```ruby gitlab_shell['secret_token'] = 'fbfb19c355066a9afb030992231c4a363357f77345edd0f2e772359e5be59b02538e1fa6cae8f93f7d23355341cea2b93600dab6d6c3edcdced558fc6d739860' gitlab_rails['otp_key_base'] = 'b719fe119132c7810908bba18315259ed12888d4f5ee5430c42a776d840a396799b0a5ef0a801348c8a357f07aa72bbd58e25a84b8f247a25c72f539c7a6c5fa' gitlab_rails['secret_key_base'] = '6e657410d57c71b4fc3ed0d694e7842b1895a8b401d812c17fe61caf95b48a6d703cb53c112bc01ebd197a85da81b18e29682040e99b4f26594772a4a2c98c6d' gitlab_rails['db_key_base'] = 'bf2e47b68d6cafaef1d767e628b619365becf27571e10f196f98dc85e7771042b9203199d39aff91fcb6837c8ed83f2a912b278da50999bb11a2fbc0fba52964' ``` 1. Run `touch /etc/gitlab/skip-auto-reconfigure` to prevent database migrations from running on upgrade. Only the primary GitLab application server should handle migrations. 1. **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. 1. Run `sudo gitlab-ctl reconfigure` to compile the configuration. ## Enable Monitoring > [Introduced](https://gitlab.com/gitlab-org/omnibus-gitlab/issues/3786) in GitLab 12.0. If you enable Monitoring, it must be enabled on **all** GitLab servers. 1. Create/edit `/etc/gitlab/gitlab.rb` and add the following configuration: ```ruby # Enable service discovery for Prometheus consul['enable'] = true consul['monitoring_service_discovery'] = true # Replace placeholders # Y.Y.Y.Y consul1.gitlab.example.com Z.Z.Z.Z # with the addresses of the Consul server nodes consul['configuration'] = { retry_join: %w(Y.Y.Y.Y consul1.gitlab.example.com Z.Z.Z.Z), } # Set the network addresses that the exporters will listen on node_exporter['listen_address'] = '0.0.0.0:9100' gitlab_workhorse['prometheus_listen_addr'] = '0.0.0.0:9229' sidekiq['listen_address'] = "0.0.0.0" unicorn['listen'] = '0.0.0.0' # Add the monitoring node's IP address to the monitoring whitelist and allow it to scrape the NGINX metrics # Replace placeholder # monitoring.gitlab.example.com # with the addresses gathered for the monitoring node gitlab_rails['monitoring_whitelist'] = ['monitoring.gitlab.example.com'] nginx['status']['options']['allow'] = ['monitoring.gitlab.example.com'] ``` 1. Run `sudo gitlab-ctl reconfigure` to compile the configuration. > **Warning:** After changing `unicorn['listen']` in `gitlab.rb`, and running `sudo gitlab-ctl reconfigure`, it can take an extended period of time for unicorn to complete reloading after receiving a `HUP`. For more information, see the [issue](https://gitlab.com/gitlab-org/omnibus-gitlab/issues/4401). ## 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. --- ## Upgrading GitLab HA GitLab HA installations can be upgraded with no downtime, but the upgrade process must be carefully coordinated to avoid failures. See the [Omnibus GitLab multi-node upgrade document](https://docs.gitlab.com/omnibus/update/#multi-node--ha-deployment) for more details. Read more on high-availability configuration: 1. [Configure the database](database.md) 1. [Configure Redis](redis.md) 1. [Configure NFS](nfs.md) 1. [Configure the load balancers](load_balancer.md)