Runtime env variables with git branch filter

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1

I use GitHub actions to deploy preview versions with custom git branch (per this guide). Specifically, I provide --git-branch flag when pulling env variables:

vercel pull --yes --environment=preview --git-branch=my-feature

After deploying, all build-time env variables are correctly filtered by git-branch=my-feature and inlined into output bundle.
But server-side (runtime) env variables are taken from preview env without filtering by --git-branch=my-feature. Actually, the final deployment is a mix that uses branch-filtered env variables on client and non-branch-filtered variables on server. It leads to bugs in our application and obviously is invalid output.

I know about --env flag for vercel deploy. But it defines only single env variable. After vercel pull I have all my variables in .vercel/.env.preview.local. I don’t see a flag to provide a whole env file to vercel deploy. I can write a script that iterates all variables in env file and passes them as --env arguments. But this is quite weird solution.

Do you have any suggestions how to provide branch-filtered env variables to vercel runtime similar to build-time?

2

Hi, @vitaliypotapov! Welcome to the Vercel Community :smile:

Thank you for providing such detailed information!

Instead of relying on the .vercel/.env.preview.local file created by vercel pull, you can use the vercel env pull command to fetch the environment variables specific to your branch. This command supports the --git-branch flag .

 vercel env pull .env.production --environment=preview --git-branch=my-featurevercel env pull .env.production --environment=preview --git-branch=my-feature

This will create a .env.production file with the branch-specific variables.

After pulling the environment variables, you can use the --env-file flag with vercel deploy to specify the file containing your environment variables .

 vercel deploy --prebuilt --env-file=.env.productionvercel deploy --prebuilt --env-file=.env.production

You can modify your GitHub Action workflow to include these steps:

 - name: Pull Vercel Environment Information- name: Pull Vercel Environment Information
  run: vercel pull --yes --environment=preview --git-branch=${{ github.head_ref }}

- name: Pull Branch-Specific Environment Variables
  run: vercel env pull .env.production --environment=preview --git-branch=${{ github.head_ref }}

- name: Build Project Artifacts
  run: vercel build --prod --token=${{ secrets.VERCEL_TOKEN }}

- name: Deploy Project Artifacts to Vercel
  run: vercel deploy --prebuilt --prod --token=${{ secrets.VERCEL_TOKEN }} --env-file=.env.production

This approach should ensure that both build-time and runtime environment variables are correctly filtered by the git branch.

Some relevant guides that may help:

Let us know how you get on!

3

This does not help, I’m getting an error:

Vercel CLI 37.14.0
Error: unknown or unexpected option: --env-file
4

@pawlean could you check my response?

5

Can you remove the option --env-file in your command? Does it work then?

6

When I remove --env-file option, vercel deploy command works, but it uses incorrect env variables (see my initial message).

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