Lighthouse

Lighthouse is a lightweight ChatOps based webhook handler which can trigger Jenkins X Pipelines on webhooks from multiple git providers such as: GitHub, GitHub Enterprise, GitLab, and BitBucket Server. It is a successor to Prow, providing support for more SCM providers, a smaller footprint, and an easier path to adding features going forward. Lighthouse has been the default webhook handler in Jenkins X since early May, 2020.

Currently Lighthouse is focused on using Jenkins X Pipelines with tekton.

Features

Currently Lighthouse supports the common prow plugins and handles push webhooks to branches & Pull Request webhooks to then trigger Jenkins X pipelines.

Lighthouse uses the same config.yaml and plugins.yaml file structure from Prow so that we can easily migrate from prow <-> lighthouse.

This also means we get to reuse the clean generation of Prow configuration from the SourceRepository, SourceRepositoryGroup and Scheduler CRDs integrated into jx boot. e.g. here’s the default scheduler configuration which is used for any project imported into your Jenkins X cluster; without you having to touch the actual prow configuration files. You can create many schedulers and associate them to different SourceRepository resources.

We can also reuse Prow’s capability of defining many separate pipelines on a repository (for PRs or releases) via having separate contexts. Then on a Pull Request we can use /test something or /test all to trigger pipelines and use the /ok-to-test and /approve or /lgtm commands

Using Lighthouse with boot

We have integrated lighthouse into jx boot. To switch to lighthouse from prow you need to add something like this to your jx-requirements.yml file:

webhook: lighthouse

Once you have modified your jx-requirements.yml file you just need to run jx boot.

If you are using something else other than github.com as your git provider you will also require some extra YAML to configure the git provider. Here are some examples:

GitHub Enterprise

cluster:
  provider: gke
  zone: europe-west1-c
  environmentGitOwner: myowner
  gitKind: github
  gitName: ghe
  gitServer: https://my-github.com
webhook: lighthouse

BitBucket Server

cluster:
  provider: gke
  environmentGitOwner: myowner
  gitKind: bitbucketserver
  gitName: bs
  gitServer: https://my-bitbucket-server.com
webhook: lighthouse

GitLab

cluster:
  provider: gke
  environmentGitOwner: myowner
  gitKind: gitlab
  gitName: gitlab
  gitServer: https://my-gitlab-server.com
webhook: lighthouse

Comparisons to Prow

Lighthouse is based on a fork of Prow’s source code, including most of the built-in plugins from prow

The most noteworthy differences are:

• In order to support multiple SCM providers, Lighthouse uses jenkins-x/go-scm as an abstraction layer, allowing additional provider support to be implemented without needing significant changes within Lighthouse itself.
• Lighthouse has less moving parts and potential configuration than Prow, resulting in only four pods being run for Lighthouse: two webhook receiver replicas, a Keeper pod, which handles deciding when to merge and actually merging pull requests, and a Foghorn pod, which handles reporting commit statuses back to the provider.

Porting Prow commands

If there are any Prow commands you want which we’ve not yet ported over, it’s relatively easy to port Prow plugins.

We’ve reused the Prow plugin code and configuration code as the basis for Lighthouse; so its mostly a case of switching imports of k8s.io/test-infra/prow to github.com/jenkins-x/lighthouse - then modifying the github client structs from, say, github.PullRequest to scm.PullRequest.

Most of the GitHub structs map 1-1 with the jenkins-x/go-scm equivalents (e.g. Issue, Commit, PullRequest) though the go-scm API does tend to return slices to pointers to resources by default. There are some naming differences at different parts of the API though.

e.g. compare the githubClient API for the Prow lgtm versus the scmProviderClient API for the Lighthouse lgtm.

All the Prow-descended plugin related code lives in the pkg/plugins tree of packages. Mostly all we’ve done is switch to using jenkins-x/go-scm and switch out the current Prow agents and instead use a single tekton agent using the PipelineLauncher to trigger pipelines.

Environment variables

The following environment variables are used:

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