Allow advanced configuration of GitLab runner when installing GitLab managed apps

Problem to solve

Our current implementation of the GitLab runner chart does not allow for configuration customization.

Target audience

Operators, developers

Further details

Using the chart to install/manage runner prevents user from having to manage linked changes, such as:

• user account it runs on
• concurrency
• where a volume is expected to be

Proposal

Provide a mechanism where user can configure the global settings of the GitLab runner.

Once GitLab Runner is deployed via kubernetes configuration, allow user to pass a config.toml file to configure advanced runner options.

What does success look like, and how can we measure that?

Track default installations vs customized Track configuration changes via GitLab post-installation

Links / references

https://docs.gitlab.com/runner/configuration/advanced-configuration.html#the-global-section