Configuring Postgres Service Container

[ml-sherpa]

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What's the best way to configure a postgres service container in github actions. Specifically I want to configure max_locks_per_transaction when the container starts.

• I can't use an environment variable as these are not used for configuring the server.
• I can't mount a volume because services are started before the repo is checked out so I can't mount a postgresql.conf file.
• The docker container create doesn't seem to have a way to pass command arguments so I can't specify CMD ["postgres", "-c", "max_locks_per_transaction=1024"]
• docker container create will accept --entrypoint but I have the same issue as I had trying to mount postgresql.conf. The repo is not checked out.

[ghost]

Hi. Since environment variables and mounting volumes are not feasible options for you, one workaround could be to create a custom Docker image with the desired PostgreSQL configuration and then use that image in your GitHub Actions workflow. You can pre-configure the max_locks_per_transaction setting in the Dockerfile itself.

1. Now, please create a Dockerfile in your project directory:

FROM postgres:latest

# Set max_locks_per_transaction
RUN echo "max_locks_per_transaction = 1024" >> /etc/postgresql/postgresql.conf

2. Build the Docker image:

docker build -t my-custom-postgres .

3. Push the Docker image to a container registry accessible to your GitHub Actions workflow.

4. In your GitHub Actions workflow, use the custom Docker image instead of the default PostgreSQL image:

jobs:
  build:
    runs-on: ubuntu-latest

    services:
      postgres:
        image: my-custom-postgres
        ports:
          - 5432:5432
        options: --name postgresql

    steps:
      # Your steps here

By using a custom Docker image with the desired PostgreSQL configuration, you can ensure that the max_locks_per_transaction setting is applied when the container starts, even in the context of GitHub Actions.

[ml-sherpa]

Ya, that's the route I went down

FROM postgres:latest
CMD ["postgres", "-c", "max_locks_per_transaction=1024"]

[jshields]

Note when going down this path that due to other missing functionality in GitHub Actions, it is not possible to securely use OIDC with a privately hosted custom image (such as on ECR). The temporary credentials will be unmasked as plaintext and potentially exposed in logs.
https://github.com/orgs/community/discussions/25225#discussioncomment-9172039