Remote cache hits between github actions envs and .env.local envs

[agualis]

Summary

In turbo.json I have a build task that has .env.local inside inputs option (as recommended in the official turbo docs).

  "build": {
      "dependsOn": ["^build"],
      "inputs": ["$TURBO_DEFAULT$", ".env.local"],
      "outputs": [".next/**", "!.next/cache/**"]
    },

in the same turbo.json I have some global env vars that are used in the build process:

  "globalEnv": [
    "FOO",
    "BAR",

]

My checks.yml in github actions uses those envs:

env:
  FOO:1
  BAR:2 

jobs:
  Build:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - name: Setup
        uses: ./.github/actions/setup
      - name: Run build
        run: pnpm run build # Calls turbo build

If a user runs turbo build with this .env.local content:

  FOO=1
  BAR=2 

The local build output and the CI build output should be equivalent but there will never be a cache hit cause in CI .env.local won't be defined, so turbo inputs (and generated cache) will be always different .

Is there a way to address that setup?

Thanks in advance!

Examples

Scenario 1

I have a turborepo with, for instance, a nextjs app and some packages.

I have a github action to:

1. Run the build script
2. Run e2e tests pointing to that build

If a user locally runs a build with the same envs and pushes it to the remote cache, I would expect CI to get the build from the remote cache.

Scenario 2

Vercel runs preview deployments in every PR but, even if using the same env values, it will never hit user cached builds due to the same reason above (users run builds with .env.local while vercel runs builds with plain system envs defined in the vercel console).

[anthonyshew]

We don't currently capture this in our model, but could.

For context, how it works today, we take the whole content of a file input (the .env.local) as a value itself, but don't inspect the values inside. We don't read them as "something on the environment". It's just a file like any other, so the real environment variables are an entirely different hashing input.