With GitLab Pages, you can publish static websites directly from a repository in GitLab. By default, we cannot have preview pages: if a job deploys the pages, this overwrites previous content, which disallows preview mode.
Some article on the internet show how to get around that with artifacts, knowing that GitLab can display artifacts. But this trick has disadvantages, mainly highly technical links, that have to be shared again after changes on the branch.
Some Github gist points into the right direction, but in a complex way and with too few side features.
In this article, we will get around the limitation by taking advantage of the cache mechanism, and be able to display per-branch content, with the side benefit of obfuscating the path to ephemeral branches content, if desired.
The solution can be broken down to these steps :
- Generate files for current branch
- Get previous branches generation from GitLab cache
- Merge and update cache
- Auto delete obsolete cache on branch deletion, using GitLab environments
We assume you already have a way of generating your HTML static content, and just want to serve the files using GitLab Pages.
For the code to work, your cache must be centralized, either by using gitlab.com runners, by having a single runner, or by sharing caches between multiple private runners.
You need to accept a global cache by deactivating the GiLab option
Use separate caches for protected branches in Settings -> CICD -> General Pipelines.
workflow: rules: # disable tag pipelines and duplicate MR pipelines - if: $CI_COMMIT_BRANCH variables: EPHEMERAL_BRANCHES_PATH: preview # subpath to ephemeral branches content for preview, anything will work pages: stage: build image: alpine:3.18 cache: key: gitlab-pages paths: [public] before_script: # default available 'tree' app in alpine image does not work as intended - apk add tree # CURRENT_CONTENT_PATH is defined in rules, different between main branch and ephemeral branches - mkdir -p public/$CURRENT_CONTENT_PATH && ls public/$CURRENT_CONTENT_PATH/.. - | # avoid deleting main branch content when cache has been erased if [ "$CI_COMMIT_BRANCH" != "$CI_DEFAULT_BRANCH" ] && [ ! -d public/$CI_DEFAULT_BRANCH ]; then echo -e "💥\e[91;1m Unable to retrieve $CI_DEFAULT_BRANCH generated files from cache ; please regenerate $CI_DEFAULT_BRANCH files first\e[0m" exit 1 fi - rm -rf public/$CURRENT_CONTENT_PATH || true # remove last version of current branch script: - ./generate-my-html.sh --output build-docs || true # insert here your code that generates documentation - mv --verbose build-docs public/$CURRENT_CONTENT_PATH - cd public/$EPHEMERAL_BRANCHES_PATH - tree -d -H '.' -L 1 --noreport --charset utf-8 -T "Versions" -o index.html # generate a root HTML listing all previews for easier access environment: name: pages/$CI_COMMIT_BRANCH action: start url: $CI_PAGES_URL/$CURRENT_CONTENT_PATH on_stop: pages-clean-preview rules: # 'main branch' is exposed at GitLab Pages root - if: $CI_COMMIT_BRANCH == $CI_DEFAULT_BRANCH variables: CURRENT_CONTENT_PATH: "." # other (short-lived) branches generation are exposed in 'EPHEMERAL_BRANCHES_PATH/branch-name-sanitized' sub path - variables: CURRENT_CONTENT_PATH: $EPHEMERAL_BRANCHES_PATH/$CI_COMMIT_REF_SLUG artifacts: paths: [public] expire_in: 1h pages-clean-preview: stage: build image: alpine:3.18 cache: key: gitlab-pages paths: [public] variables: GIT_STRATEGY: none # git files not available after branch deletion FOLDER_TO_DELETE: $EPHEMERAL_BRANCHES_PATH/$CI_COMMIT_REF_SLUG # an indirection to allow arbitrary deletion when launching this job script: - rm -rf public/$FOLDER_TO_DELETE environment: name: pages/$CI_COMMIT_BRANCH action: stop rules: - if: $CI_COMMIT_BRANCH != $CI_DEFAULT_BRANCH when: manual allow_failure: true
The above code has below features :
maincontent is exposed on
$CI_PAGES_URLand the path is configurable with
- Per-branch preview content is exposed on
$CI_PAGES_URL/preview, with a homepage to easily navigate to branches content
- Path to root preview folder is configurable with
$EPHEMERAL_BRANCHES_PATHvariable to hide preview content by obfuscation
- Generated pages are associated with environments to take advantage of auto-cleaning on branch deletion
- To avoid disturbing already existing environments, pages environment are placed under a
maincontent has not been generated in current cache, or if the cache has been deleted, an error is triggered, to avoid accidental deletion
- Deletion job can be triggered manually with any cache path as input, to clean outdated data
- Code can safely be added to an existing project pipeline without causing trouble with already existing jobs
workflow:rulescan be deleted if you already have your own, or updated to match your flow
- The job must be named
pagesand the artifact must be a
publicfolder to be deployed to GitLab Pages (or you can use the pages:publish keyword)
Given the piece of yaml provided, using it in your pipeline, you should be able to share your GitLab Pages on a per-branch basis, on the path you want, while serving the stable content from the root context.
For any question or remark, please use below comment section 🤓.
If you need information to choose better runner architecture, you can read GitLab Runners topologies: pros and cons.
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