Getting started with an offline GitLab Installation

This is a step-by-step guide that helps you install, configure, and use a self-managed GitLab instance entirely offline.

Installation

NOTE: Note: This guide assumes the server is Ubuntu 18.04. Instructions for other servers may vary.

NOTE: Note: This guide assumes the server host resolves as my-host, which you should replace with your server's name.

Follow the installation instructions as outlined in the omnibus install guide, but make sure to specify an http URL for the EXTERNAL_URL installation step. Once installed, we will manually configure the SSL ourselves.

It is strongly recommended to setup a domain for IP resolution rather than bind to the server's IP address. This better ensures a stable target for our certs' CN and will make long-term resolution simpler.

sudo EXTERNAL_URL="http://my-host.internal" install gitlab-ee

Enabling SSL

Follow these steps to enable SSL for your fresh instance. Note that these steps reflect those for manually configuring SSL in Omnibus's NGINX configuration:

Make the following changes to /etc/gitlab/gitlab.rb:

# Update external_url from "http" to "https"
external_url "https://example.gitlab.com"

# Set Let's Encrypt to false
letsencrypt['enable'] = false

Create the following directories with the appropriate permissions for generating self-signed certificates:

sudo mkdir -p /etc/gitlab/ssl
sudo chmod 755 /etc/gitlab/ssl
sudo openssl req -x509 -nodes -days 365 -newkey rsa:2048 -keyout /etc/gitlab/ssl/my-host.internal.key -out /etc/gitlab/ssl/my-host.internal.crt

Reconfigure your instance to apply the changes:
```
sudo gitlab-ctl reconfigure
```

Enabling the GitLab Container Registry

Follow these steps to enable the container registry. Note that these steps reflect those for configuring the container registry under an existing domain:

Make the following changes to /etc/gitlab/gitlab.rb:

# Change external_registry_url to match external_url, but append the port 4567
external_url "https://example.gitlab.com"
registry_external_url "https://example.gitlab.com:4567"

Reconfigure your instance to apply the changes:
```
sudo gitlab-ctl reconfigure
```

Allow the Docker daemon to trust the registry and GitLab Runner

Provide your Docker daemon with your certs by following the steps for using trusted certificates with your registry:

sudo mkdir -p /etc/docker/certs.d/my-host.internal:5000

sudo cp /etc/gitlab/ssl/my-host.internal.crt /etc/docker/certs.d/my-host.internal:5000/ca.crt

Provide your GitLab Runner (to be installed next) with your certs by following the steps for using trusted certificates with your Runner:

sudo mkdir -p /etc/gitlab-runner/certs

sudo cp /etc/gitlab/ssl/my-host.internal.crt /etc/gitlab-runner/certs/ca.crt

Enabling GitLab Runner

$ sudo docker run --rm -it -v /etc/gitlab-runner:/etc/gitlab-runner gitlab/gitlab-runner register
Updating CA certificates...
Runtime platform                                    arch=amd64 os=linux pid=7 revision=1b659122 version=12.8.0
Running in system-mode.

Please enter the gitlab-ci coordinator URL (e.g. https://gitlab.com/):
https://my-host.internal
Please enter the gitlab-ci token for this runner:
XXXXXXXXXXX
Please enter the gitlab-ci description for this runner:
[eb18856e13c0]:
Please enter the gitlab-ci tags for this runner (comma separated):

Registering runner... succeeded                     runner=FSMwkvLZ
Please enter the executor: custom, docker, virtualbox, kubernetes, docker+machine, docker-ssh+machine, docker-ssh, parallels, shell, ssh:
docker
Please enter the default Docker image (e.g. ruby:2.6):
ruby:2.6
Runner registered successfully. Feel free to start it, but if it's running already the config should be automatically reloaded!

Now we must add some additional configuration to our runner:

Make the following changes to /etc/gitlab-runner/config.toml:

Add Docker socket to volumes volumes = ["/var/run/docker.sock:/var/run/docker.sock", "/cache"]
Add pull_policy = "if-not-present" to the executor configuration

Now we can start our Runner:

sudo docker run -d --restart always --name gitlab-runner -v /etc/gitlab-runner:/etc/gitlab-runner -v /var/run/docker.sock:/var/run/docker.sock gitlab/gitlab-runner:latest
90646b6587127906a4ee3f2e51454c6e1f10f26fc7a0b03d9928d8d0d5897b64

Authenticating the registry against the host OS

As noted in Docker's registry authentication documentation, certain versions of Docker require trusting the certificate chain at the OS level.

In the case of Ubuntu, this involves using update-ca-certificates:

sudo cp /etc/docker/certs.d/my-host.internal\:5000/ca.crt /usr/local/share/ca-certificates/my-host.internal.crt

sudo update-ca-certificates

If all goes well, this is what you should see:

1 added, 0 removed; done.
Running hooks in /etc/ca-certificates/update.d...
done.

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