Staging

How staging.kernelci.org works

While the production instance is hosted on linux.kernelci.org, another independent instance is hosted on staging.kernelci.org. This is where all the changes to the KernelCI code and configuration get tested before getting merged and deployed in production. It consists of a Jenkins instance on bot.staging.kernelci.org, a Mongo database with a kernelci-backend instance and a kernelci-frontend instance for the web dashboard.

Jobs are run every 8h on staging, using all the code from open pull requests on GitHub. The kernel revisions being tested are rotating between mainline, stable and linux-next. An extra commit and a staging tag is created on top of each branch to artifically create a new revision in the KernelCI kernel tree even if there was no changes upstream, to ensure that jobs are run with a separate set of results. A reduced set of build configurations is used to limit the resources used on staging and to get results quicker.

There is also a plain mainline build every day, and a full linux-next build every Friday to at least have some complete coverage and potentially catch issues that can’t be seen with the reduced number of configs in staging builds.

GitHub pull requests

A special feature of the staging instance is the ability to test code from open GitHub pull requests before they get merged. This is handled by tools in the kernelci-deploy project, to pull all the open pull requests for a given project, apply some arbitrary patches and push a resulting staging.kernelci.org branch back to the repository with a tag. This branch is being replaced (force-pushed) every time the tool is run.

Things to note:

  • Pull requests are only merged from users that are on a trusted list, stored in the kernelci-deploy configuration files.
  • Pull requests are merged in chronological order, so older ones take precedence.
  • Pull requests that fail to merge are ignored and will not be tested.
  • Pull requests will be skipped and not merged if they have the staging-skip label set.
  • If any patch from kernelci-deploy doesn’t apply, the resulting branch is not pushed. It is required that all the patches always apply since some of them are necessary to adjust the staging behaviour (say, to not send bisection email reports). They will need to get updated if they conflict with pending PRs.
  • A tag is created with the current date and pushed with the branch.

Jenkins: bot.staging.kernelci.org

The staging instance is running Jenkins, just like production. The main difference is that the staging one is publicly visible, read-only for anonymous users: bot.staging.kernelci.org

This allows for the job logs to be inspected. Also, some developers have a personal folder there to run modified versions of the Jenkins job but still using the available resources (builders, API tokens to submit jobs in test labs…).

Run every 8h

There is a timer on the staging.kernelci.org server which starts a job every 8h, so 3 times per day. The job does the following:

  1. update staging branch for kernelci-jenkins
  2. recreate Jenkins jobs by running the job-dsl “seed” job
  3. update staging branch for kernelci-core
  4. update staging branch for kernelci-backend
  5. update the kernelci-backend service using Ansible from kernelci-backend-config with the staging branch
  6. update staging branch for kernelci-frontend
  7. update the kernelci-frontend service using Ansible from kernelci-frontend-config with the staging branch
  8. create and push a staging.kernelci.org branch with a tag to the KernelCI kernel repo
  9. trigger a monitor job in Jenkins with the kernelci_staging config

The last step should cause the monitor job to detect that the staging kernel branch has been updated, and run a kernel build trigger job which in turn will cause tests to be run. Builds and test results will be sent to the staging backend instance, and results will be available on the staging web dashboard. Regressions will cause bisections to be run on the staging instance, and results to be sent to the kernelci-results-staging@groups.io mailing list.

Last modified July 22, 2021