GitLab Geo configuration

Note: This is the documentation for the Omnibus GitLab packages. For installations from source, follow the GitLab Geo nodes configuration for installations from source guide.

Note: Stages of the setup process must be completed in the documented order. Before attempting the steps in this stage, complete all prior stages.

Install GitLab Enterprise Edition on the server that will serve as the secondary Geo node. Do not login or set up anything else in the secondary node for the moment.
Upload the GitLab License to the primary Geo Node to unlock GitLab Geo.
Setup the database replication (primary (read-write) <-> secondary (read-only) topology).
Configure SSH authorizations to use the database
Configure GitLab to set the primary and secondary nodes.
Optional: Configure a secondary LDAP server for the secondary.
Follow the after setup steps.

This is the final step you need to follow in order to setup a Geo node.

You are encouraged to first read through all the steps before executing them in your testing/production environment.

Setting up GitLab

Notes:

Do not setup any custom authentication in the secondary nodes, this will be handled by the primary node.

Do not add anything in the secondaries Geo nodes admin area (Admin Area ➔ Geo Nodes). This is handled solely by the primary node.

After having installed GitLab Enterprise Edition in the instance that will serve as a Geo node and set up the database replication, the next steps can be summed up to:

Replicate some required configurations between the primary and the secondaries
Configure a second, tracking database on each secondary
Start GitLab on the secondary node's machine

Prerequisites

This is the last step of configuring a Geo secondary node. Make sure you have followed the first two steps of the Setup instructions:

You have already installed on the secondary server the same version of GitLab Enterprise Edition that is present on the primary server.
You have set up the database replication.
Your secondary node is allowed to communicate via HTTP/HTTPS with your primary node (make sure your firewall is not blocking that).
Your nodes must have an NTP service running to synchronize the clocks. You can use different timezones, but the hour relative to UTC can't be more than 60 seconds off from each node.

Step 1. Copying the database encryption key

GitLab stores a unique encryption key in disk that we use to safely store sensitive data in the database. Any secondary node must have the exact same value for db_key_base as defined in the primary one.

SSH into the primary node and login as root:
```
sudo -i
```
Execute the command below to display the current encryption key and copy it:
```
 gitlab-rake geo:db:show_encryption_key
```
SSH into the secondary node and login as root:
```
sudo -i
```
Add the following to /etc/gitlab/gitlab.rb, replacing encryption-key with the output of the previous command:
```
 gitlab_rails['db_key_base'] = "encryption-key"
```
Reconfigure the secondary node for the change to take effect:
```
gitlab-ctl reconfigure
```

Once reconfigured, the secondary will start automatically replicating missing data from the primary in a process known as backfill. Meanwhile, the primary node will start to notify changes to the secondary, which will act on those notifications immediately. Make sure the secondary instance is running and accessible.

Step 2. Enabling hashed storage (from GitLab 10.0)

Warning Hashed storage is in Beta. It is considered experimental and not production-ready. For the latest updates, check issue. Hashed Storage is not required to run GitLab Geo, but in some edge cases race conditions can lead to errors and Geo to break. Known issues are renaming a project multiple times in short succession, deleting a project and recreating with the same name very quickly.

Using hashed storage significantly improves Geo replication - project and group renames no longer require synchronization between nodes.

Visit the primary node's Admin Area ➔ Settings (/admin/application_settings) in your browser
In the Repository Storages section, check Create new projects using hashed storage paths:

Step 3. (Optional) Configuring the secondary to trust the primary

You can safely skip this step if your primary uses a CA-issued HTTPS certificate.

If your primary is using a self-signed certificate for HTTPS support, you will need to add that certificate to the secondary's trust store. Retrieve the certificate from the primary and follow these instructions on the secondary.

Step 4. Managing the secondary GitLab node

You can monitor the status of the syncing process on a secondary node by visiting the primary node's Admin Area ➔ Geo Nodes (/admin/geo_nodes) in your browser.

Please note that if git_data_dirs is customized on the primary for multiple repository shards you must duplicate the same configuration on the secondary.

Disabling a secondary node stops the syncing process.

The two most obvious issues that replication can have here are:

Database replication not working well
Instance to instance notification not working. In that case, it can be something of the following:
- You are using a custom certificate or custom CA (see the Troubleshooting section)
- Instance is firewalled (check your firewall rules)

Currently, this is what is synced:

Git repositories
Wikis
LFS objects
Issue, merge request, snippet and comment attachments
User, group, and project avatars

Next steps

Your nodes should now be ready to use. You can login to the secondary node with the same credentials as used in the primary. Visit the secondary node's Admin Area ➔ Geo Nodes (/admin/geo_nodes) in your browser to check if it's correctly identified as a secondary Geo node and if Geo is enabled.

If your installation isn't working properly, check the troubleshooting section.

Point your users to the after setup steps.

Selective replication

With GitLab 9.5, GitLab Geo now supports the first iteration of selective replication, which allows admins to choose which groups should be replicated by secondary nodes.

It is important to notice that selective replication:

Does not restrict permissions from secondary nodes.
Does not hide projects metadata from secondary nodes. Since Geo currently relies on PostgreSQL replication, all project metadata gets replicated to secondary nodes, but repositories that have not been selected will be empty.
Secondary nodes won't pull repositories that do not belong to the selected groups to be replicated.

Replicating wikis and repositories over SSH

Warning: In GitLab 10.2, replicating repositories and wikis over SSH was deprecated. Support for SSH replication will be removed in 10.3. These instructions should only be used if you need to add a new secondary in the short term.

SSH into the secondary node and login as root:
```
sudo -i
```
Add the primary's SSH key fingerprint to the known_hosts file.
```
sudo -u git -H ssh git@<primary-node-url>
```
Replace <primary-node-url> with the FQDN of the primary node. You should manually check the displayed fingerprint against a trusted record of the expected value before accepting it!

Generate a passphraseless SSH keypair for the git user, and capture the public component:

test -e ~git/.ssh/id_rsa || sudo -u git -H ssh-keygen -q -t rsa -b 4096 -f ~git/.ssh/id_rsa
cat ~git/.ssh/id_rsa.pub

Follow the steps above to set up the new Geo node. When you reach Step 4: Enabling the secondary GitLab node select "SSH (deprecated)" instead of "HTTP/HTTPS", and populate the "Public Key" with the output of the previous command (beginning ssh-rsa AAAA...).

Upgrading Geo

See the updating the Geo nodes document.

Troubleshooting

See the troubleshooting document.