<!--IssueSummary start--> <details> <summary> Everyone can contribute. [Help move this issue forward](https://handbook.gitlab.com/handbook/marketing/developer-relations/contributor-success/community-contributors-workflows/#contributor-links) while earning points, leveling up and collecting rewards. </summary> - [Close this issue](https://contributors.gitlab.com/manage-issue?action=close&projectId=278964&issueIid=215575) </details> <!--IssueSummary end--> ### Problem to Solve Currently validating the `.gitlab-ci.yml` file requires users to visit a special `ci/lint` URL within their project and manually copy the contents of their file. If the configuration is not valid, users have to edit that file and then finally copy/paste the valid one back to their editor and commit the changes. ### Proposal Users who are editing the `.gitlab-ci.yml` file in the Web IDE should have access to a `validate` button that runs the current contents of the file through the validator and provides feedback to users.  | Description | Error | Success | | ------ | ------ | ------ | | Default |  |  | | Dark |  |  | Clicking `Validate` would call the [Lint API](https://docs.gitlab.com/ee/api/lint.html) and then provide feedback to users in the validation tab. ### Availability and Testing The new feature will require some test coverage, system tests and possibly an E2E (depending on how much usage we expect it to get).