Is it possible to invalidate build cache on a given branch?

Question

I'm using Gitlab CI on one of my projects and I face the following problem :

• My master build fails since a lot of time...
• I push a new branch built from the master (no new commits) and push it, the build works.

I think that it's related to build cache because the codebase is strictly the same... The latest valid build cache may make the current code base failed...

Is there a way to clean the build cache on a specific branch ? In my case the master ? From the API ?

Answer 1

Finally, the Gitlab Team gave me the solution on Twitter : https://twitter.com/gitlab/status/832674380790394880

Since my repository is hosted on gitlab.com, I can't remove the cache by myself. But on the .gitlab-ci.yml file documentation, it's explained that we can use a cache:key entry.

This cache:key is used to determine how the cache entry is named so I can change the default value to start on a blank cache 😊.

Below a sample of my .gitlab-ci.yml file :

my-asset-build:
  cache:
    key: "$CI_COMMIT_REF_NAME-assets"

With that configuration, my cache is related to the current ref (so a build on the same ref will use the cache) with a suffix !

Thanks to the Gitlab Team for their quick answer on Twitter !

If you have trouble with the variable name, maybe you need to check this page : https://docs.gitlab.com/ce/ci/variables/README.html#9-0-renaming

Also, since Gitlab 10.4, we have a "Clear runner cache" button in the pipeline list. Clicking on that button will have the same effect than changing variable name without polluting commit history.