Can I override Vercel system environment variables in GitHub Actions?

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Hi Jonghun!

Great question. You’ve touched on some important aspects of Vercel’s environment handling. Let me clarify a few points and suggest a workable solution:

  1. The Pro plan limitation you mentioned applies to custom environment variables, not system ones like original_environment and environment. These system variables are internal to Vercel and can’t be directly overridden, regardless of the plan.
  2. You’re correct that the API modifies original_environment and environment. This is by design and part of Vercel’s deployment process.
  3. Instead of trying to override these system values, you should:
    a) Use Vercel’s built-in environment detection
    b) Structure your application to handle environment-specific logic based on other available environment variables

Here’s an example of how you can achieve this in your GitHub Actions workflow:

name: Deploy to Vercel
on:
  push:
    branches: [main, staging]
jobs:
  deploy:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v2
      - name: Deploy to Vercel
        env:
          VERCEL_TOKEN: ${{ secrets.VERCEL_TOKEN }}
        run: |
          npx vercel --token ${VERCEL_TOKEN} \
                     --env APP_ENV=${GITHUB_REF##*/} \
                     --prod

This approach:

  1. Uses the GitHub ref to set a custom APP_ENV variable
  2. Deploys to Vercel using their CLI, which respects the automatic branch detection
  3. Allows you to use APP_ENV in your application to determine the environment, rather than relying on Vercel’s system variables

In your application code, you can then use APP_ENV (or VERCEL_ENV if you prefer Vercel’s built-in variable) to handle environment-specific logic.

Let us know how you get on!