How to pass custom environment variables to the Lightsale instance?

[Eslam Hindawy]

Hello, is it possible to set custom environment variables to be passed to the Lightsale instance?

To give more context, I'm trying to achieve the following workflow:

1. A Docker image will be built for every PR and pushed to Github Container Registry, the image will be tagged with pr-XXX where XXX: pull request number
2. Pull preview action should pull the created docker image for the PR and start the service

Since each PR would have a different image, I changed docker-compose.pullpreview.yml to read the image as an Environment variable

docker-compose.pullpreview.yml

version: "3.8"
  web:
    image: ${IMAGE:?err}

Ideally this environment variable should be set from Github action since there it's known what's the PR number and accordingly we can construct the image name

Github action (pullpreview.yml)

- name: Pullpreview action
        uses: pullpreview/action@v5
        with:
          registries: docker://${{ github.repository_owner }}:${{ secrets.GITHUB_TOKEN }}@ghcr.io
        env:
          IMAGE: ghcr.io/org/repo:pr-${{ github.event.number }}

But unfortunately this doesn't work, I always get this error:

parsing /app/docker-compose.pullpreview.yml: error while interpolating services.web.image: required variable IMAGE is missing a value: err

I also checked on the Lightsale instance, and the env variable IMAGE is not set

ssh ec2-user@x.x.x.x
printenv

P.S. I only included snippets of docker-compose.pullpreview.yml and pullpreview.yml that are relevant, if you need more details please let me know.

Thanks,
Eslam

[Cyril Rohr]

@bigsolom Hello! When the workflow starts, the pullpreview action runs on the GitHub runner, not on the lightsail instance. As such, any environment variable that you set on the action will only be seen from the GitHub runner.

2 ways to achieve your objective:

• add a step before the pullpreview action, which simply replaces the image value using sed, e.g.

steps:
  - name: Configure pullpreview
    env:
      MY_IMAGE: ...
    run: sed -i "s|image: REPLACE_ME|image: $MY_IMAGE|" docker-compose.pullpreview.yml
  - name: PullPreview
    uses: pullpreview/action@v5
    ...

• generate a compose file override with just the correct image name, and add that additional compose file to the compose_files input of the pullpreview action. Compose will then merge all the files at runtime:

steps:
  - name: Configure pullpreview
    env:
      MY_IMAGE: ...
    run: |
     echo "services: { my_service: { image: $MY_IMAGE } }" > docker-compose.pullpreview-override.yml
  - name: PullPreview
    uses: pullpreview/action@v5
    with:
      compose_files: docker-compose.pullpreview.yml,docker-compose.pullpreview-override.yml
    ...

[Cyril Rohr]

@bigsolom did it help?

[Eslam Hindawy]

Thanks for your answer @crohr , Yes it did help! I went for the first option "Replacing file contents using sed"

Should I close this issue now? or do you want to keep it open?

[Cyril Rohr]

Great to know this helped. I will close the issue now.