On Pipelines as Code we started to get a nice documentation website on :


The website is statically generated with Hugo and hosted on CloudFares Pages using the markdown files from the repository.

So far that’s a pretty standard stack, but what we wanted is to be able to get preview URLS like on Netlify or other CIs

There is a nice check box, that says “Generate Preview URL on Pull Request” which seems to do what we want but it doesn’t. So far it seems that Pull Request coming from forks are not processed only the one from branch coming from the same repository where the pull request is.

Since we do our own dogfood and we want anyway to use Pipelines as Code and Tekton as much as possible, I started to implement a preview environement mechanism to get a link with the changes from the pull request if the doc/ folder is modified inside the PR.

I have again used my toy webserver, go-simple-uploader (which we have been used previously for artifacts caching) to serve the static HTML generate with hugo, but first I had to make a few changes to it:

  • Added an OpenShift Route to directly expose it to the internet. It previously was only accessible via the local kubernetes service across pods.

  • I added a capability to be able to send a tarball when uploading, so we can upload a tarball of a folder and stream directly to go-simple-uploader which will uncompress it on the fly.

  • I modified the server to add authentication to the /upload endpoint via a username and password. Just to make sure nobody abuse from it.

So far so good and after having the new image deployed on our cluster, I modified our Pipelines as Code/Tekton template in the .tekton directory to get those preview URLS generated.

The whole bits added is here :

      - name: build-doc
          - fetchit
            - name: source
            - name: hugo-gen
              image: quay.io/thegeeklab/hugo
              workingDir: $(workspaces.source.path)
              script: |
                git fetch origin main && \
                  git diff --name-only FETCH_HEAD | grep -q '^docs/' || exit 0
                cd docs
                sed -i '1acanonifyURLs = true' config.toml
                hugo --gc --minify -d {{ revision }} -b https://preview-pipelines-as-code-ci.apps.paac.devcluster.openshift.com/docs/{{ revision }}
                echo "Preview URL: https://preview-pipelines-as-code-ci.apps.paac.devcluster.openshift.com/docs/{{ revision }}"                
            - name: upload-to-static-server
              # it has curl and we already pulled it
              image: registry.redhat.io/rhel8/go-toolset:1.16.12-7
              workingDir: $(workspaces.source.path)
                - name: HUB_TOKEN
                      name: "nightly-ci-github-hub-token"
                      key: "hub-token"
                - name: UPLOADER_UPLOAD_CREDENTIALS
                      name: "uploader-upload-credentials"
                      key: "credentials"
              script: |
                cd docs
                [[ -d {{ revision }} ]]  || exit 0
                tar czf - {{ revision }} | curl -u ${UPLOADER_UPLOAD_CREDENTIALS} -F path=docs -F targz=true -X POST -F [email protected] http://uploader:8080/upload
                # Post as status
                set +x
                curl -H "Authorization: Bearer ${HUB_TOKEN}" -H 'Accept: application/vnd.github.v3+json' -X POST https://api.github.com/repos/{{repo_owner}}/{{repo_name}}/statuses/{{revision}} -d '{"state": "success", "target_url": "https://preview-pipelines-as-code-ci.apps.paac.devcluster.openshift.com/docs/{{ revision }}", "description": "Generated with brio.", "context": "Pipelines as Code Preview URL"}'                

On the first step we start detecting if we had any changes in the doc/ folder using some git trickery with FETCH_HEAD, if we didn’t have any we will just exit 0 and skip it.

If we have some changes, we add a setting to the hugo config.toml file to set cannonifyURLs=true so we get canon urls instead of relative.

We are then generating the documentation using hugo and we add the new base which goes to our public route URL and the commit sha (via Pipelines as Code variable expansion).

We have another step just after, that would use the username and password from a secret on a cluster and tar gz the new docs/ folder on the file to go-simple-uploader which will upload it and uncompress it on the service.

At the end to be able to preview URL, I wasn’t sure which place to put it, we could do slack or as a comment of the pull request but this quickly become ignore and spammy. Instead, I used the GitHub statuses API to post the link inside the pull request in the CI status place of GitHub, just a click away to be previewed.


Preview URL on CI