ESLint ignores its own cache

Tell us about your environment

We have a Gitlab configured this way:

cache:
  key: $CI_COMMIT_REF_NAME
  paths:
    - .eslint

lint:
  stage: test
  script: DEBUG=eslint:cli-engine yarn lint:all

And package.json:

{
  "scripts": {
    "lint": "eslint --cache --cache-location .eslint/cache --fix --ignore-path .eslintignore",
    "lint:all": "yarn lint \"src/**/*.{js,jsx,ts,tsx}\"",
  }
}

• ESLint Version: 7.2.0

What did you expect to happen?

I can see that the ESLint cache is being successfully created on previous job launches, e.g. a file .eslint/cache is present in Gitlab Cache archive. And I expect to see that cache is used:

  eslint:cli-engine Skipping file since it hasn't changed: /xxx/src/app/core/data/stores/utils.js +0ms

What actually happened? Please include the actual, raw output from ESLint.

Looks like the cache is not used because I see output like this (for ALL the files in the repo):

  eslint:cli-engine Lint /xxx/src/app/core/data/stores/utils.js +132ms
                    ^^^^
                    this means cache was not used

But like I said, I do see the ESLint cache file being extracted from the Gitlab’s cache.

Main question to ESLint is what can cause the cache file to be ignored?

Are you willing to submit a pull request to fix this bug?

Yes, if someone points where to look.

[mdjermanovic]

Marking as “works as intended” since it isn’t a bug in the actual implementation.

I think we should improve this, probably by adding an option (e.g., as proposed in eslint/rfcs#63).

As for possible workarounds, it might be useful to track royriojas/file-entry-cache#14 (looks like it might be merged soon). It will allow for setting an env variable FILE_ENTRY_CACHE_USE_CHECKSUM which would be used directly from the file-entry-cache dependency.

[mdjermanovic]

Unfortunately, at the moment it does seem useless in this scenario. I hope we’ll be able to add better support for the use of eslint cache on CIs in some of the future versions.