• We need to tell Turborepo to pass some environment variables into the apps in the monorepo, otherwise, the environment variables won’t be available.

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Environment variable in Turborepo and Vite

Problem: Handle environment variables correctly in the Turborepo structure in Github actions.

First, we have this workflow file. Important notice here is the CODECOV_TOKEN should NOT be prefixed with VITE_

- name: Build
  run: pnpm build --filter=main
  env:
    VITE_API_KEY: ${{ secrets.VITE_API_KEY }}
    CODECOV_TOKEN: ${{ secrets.CODECOV_TOKEN }}

And in the apps/til/vite.config.ts for example

const codecovToken = process.env.CODECOV_TOKEN;
// This is always undefined in CI servers

Root cause: turborepo does NOT automatically make custom environment variables available to the build command.

After spending hours trying and failing, I finally figured out the root cause: we need to let turborepo pass down the environment variable to the build step. We need to have this passThroughEnv options in the build step in turbo.json

{
  "$schema": "https://turborepo.org/schema.json",
  "tasks": {
    "build": {
      "outputs": ["dist/**"],
      "dependsOn": ["^build"],
      "passThroughEnv": ["CODECOV_TOKEN"]
    },
  }
}