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GitLab/Gitlab Runner

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Revision as of 15:51, 3 September 2021 by imported>Jelto
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GitLab Runner is an application that works with GitLab CI/CD to run jobs in a pipeline.[1] For more information see the official GitLab Runner documentation.

Current Gitlab Runner setup (T287504)

We're currently relying on WMCS VPSs for shared runner capacity. There is a project named gitlab-runners in which to provision new instances, and a profile to help provision Docker based runners on those instances. Note that a standalone puppetmaster in the same project stores the runner registration token under /etc/puppet/secret, and Puppet autosigning is turned off to protect the token value.

Setting up a new shared runner

To set up a new shared runner, following these steps.

  1. Create a new WMCS VPS instance.
    1. Log in to [1] and navigate to the gitlab-runners project.
    2. Launch a new Debian buster instance, following the runner-{nnnn} naming convention.
    3. Add profile::gitlab::runner to the instance's Puppet Classes under the Puppet Configuration tab.
  2. Wait until the new instance has fully provisioned and you can successfully ssh to the running instance using your authorized key. (This typically takes a few minutes.)
  3. Do the little SSL dance that is required of instances that use a standalone puppetmaster.
    1. On the new runner (runner-{nnnn}
      1. Run sudo rm -rf /var/lib/puppet/ssl to remove the existing SSL certs used by the default puppetmaster.
      2. Run sudo -i puppet agent --test --verbose to have the puppet client generate a new SSL cert.
    2. On sign the new instance's SSL cert.
      1. Run sudo -i puppet cert list and find the new instance in the list.
      2. Run sudo -i puppet cert sign runner-{nnnn} to sign the client cert.
  4. Run sudo -i puppet agent --test --verbose on the runner to ensure it has fully provisioned the profile::gitlab::runner profile.
  5. Verify that the runner has successfully registered with our GitLab instance by viewing the runner list.

Future Gitlab Runner setup (T286958)

This section contains the requirements and plan for a future Gitlab-Runner setup. The goal is to find a secure, scalable and easy to build and maintain setup for the GitLab Runner infrastructure. GitLab Runner support various environments, such as Kubernetes, Docker, OpenShift or just Linux VMs. Furthermore a wide range of compute platforms can be leveraged, such as WMCS, Ganeti, bare metal hosts or public clouds. So this section tries to compare the different options and collect advantages and disadvantages. Privacy considerations can be found in the next section.

GitLab Runner environments

GitLab Runner can be installed:

The follow table tries to compare the most important GitLab Runner environments available:

Environment Advantages Disadvantages Additional considerations
  • Easy to setup
  • low maintenance
  • Similar to current solution
  • Low elasticity, difficult to scale
  • Easy to setup
  • low maintenance
  • difficult to scale
  • auto scaling needsdocker-machine
  • High elasticity/auto scaling
  • Additional Kubernetes needed (for security)
  • Additional cluster needs maintenance
  • More difficult to setup
  • Could be used to strengthen Kubernetes knowledge
  • Auto scaling needs elastic compute plattform
  • Maybe a general purpose non-production cluster can be build?
  • not in use in WMF

Compute Plattforms

The following table compares the four main computing options for the GitLab Runner setup: WMCS, Ganeti, Bare Metal or Public Cloud.

Plattform Advantages Disadvantages Additional considerations
  • High elasticity
  • Semi-trusted environment (?)
  • Kubernetes auto scaling can leverage OpenStack
  • Only in Eqiad
  • Elasticity is bound to appropriate quotas
  • Kubernetes on OpenStack is new and different from existing Kubernetes solutions
  • Trusted environment
  • medium elasticity
Bare metal
  • Trusted environment
  • Similar environment to existing Kubernetes setups
  • Low elasticity
  • Machines have to be ordered and racked
  • Could old/decommissioned machines be used as runners?
Public Cloud (e.g. GCP)
  • High elasticity
  • Low maintenance
  • Easy Kubernetes setup (e.g. GKE)
  • untrusted environment (see privacy section)
  • Dependency to cloud provider
  • Public discussion about public cloud is needed
  • Evaluation of privacy considerations is needed (see below)
Elastic demand

Privacy considerations

Whether these can safely run on a third-party platform

Monitoring of performance and usage

Gitlab-Runner export Prometheus metrics. This metrics should give insights in performance and usage. See Monitoring Gitlab Runner documentation.

However the Gitlab Runner exporter does not support authorization or https. So depending on where the Runners are hosted, a https proxy with authorization is required.