When building Python applications with Poetry in a Docker container, we sometimes encounter issues accessing private packages stored in the Google Artifact Registry (GAR). Locally, this challenge arises because docker build cannot directly handle the Google Cloud credentials in the same way as our CI/CD pipeline, where we leverage service accounts and the Kaniko action for secure builds. To resolve this for local development, we'll configure Google Cloud credentials within Docker using Docker Compose, enabling secure access to the GAR repository during the build process.

Non-Containerized

Pre-requirements

• Python ^3.12
• Poetry ^1.7.1
• Google Cloud SDK ^489.0.0
• Keyring ^24.0.0
• keyrings.google-artifactregistry-auth ^1.0.0
• Read access to your GAR Python repository
• Logged into GCP (gcloud auth application-default login)

Setup

1. Keyring Setup

   Install keyring support for Google Artifact Registry:

   pip install keyring
   pip install keyrings.google-artifactregistry-auth
   

2. Connect Poetry to your GAR repo

   Access to the private repository in the Google Artifact Registry can be managed through Poetry. First, configure a custom source in Poetry for the GAR repository by running:

   poetry source add --priority=explicit <PACKAGE_NAME> https://<REGION>-python.pkg.dev/<PROJECT>/<REGISTRY>/simple
   

Be sure to append /simple to the repository URL for compatibility.

Now you can install packages from your private repo:

poetry add --source <PACKAGE_NAME> [email protected]

Notes

In some cases, accessing the repository may require setting an explicit OAuth token for authentication in Poetry. Use the following command to configure this globally in Poetry:

poetry config http-basic.<PACKAGE_NAME> oauth2accesstoken $(gcloud auth print-access-token)

Containerized

Pre-requirements

• Docker ^20.10
• Docker Compose ^2.0
• Google Cloud SDK ^489.0.0
• Read access to your GAR Python repository
• Logged into GCP (gcloud auth application-default login)

Setup

1. Secrets Configuration

   First, define a secret in docker-compose.yaml using the local path to your credentials file:

   secrets:
     gcloud_credentials:
       file: ~/.config/gcloud/application_default_credentials.json
   

   • We define gcloud_credentials.file as a consistent path for Unix-like environments in docker-compose.yaml:

   • This configuration securely passes the credentials file from your local machine to the build context without exposing sensitive data.

2. Dockerfile Adjustments

   In the Dockerfile, we handle credentials with the following setup:

   ARG GOOGLE_APPLICATION_CREDENTIALS
   ENV GOOGLE_APPLICATION_CREDENTIALS=${GOOGLE_APPLICATION_CREDENTIALS}
   
   RUN --mount=type=secret,id=gcloud_credentials \
       mkdir -p $(dirname ${GOOGLE_APPLICATION_CREDENTIALS}) && \
       cp /run/secrets/gcloud_credentials ${GOOGLE_APPLICATION_CREDENTIALS}
   

   • --mount=type=secret,id=gcloud_credentials: Securely mounts the credentials during the build process.

   • GOOGLE_APPLICATION_CREDENTIALS: Specifies the credential file's path within the container.

3. Service Configurations

   Here, gcloud_credentials is the secret mounted at build time, as specified in the secrets configuration.

   some-service:
     build:
       context: .
       dockerfile: ./Dockerfile.local
       args:
         GOOGLE_APPLICATION_CREDENTIALS: /tmp/application_default_credentials.json
       secrets:
         - gcloud_credentials
   

Usage

Just run:

docker-compose up --build

Conclusion

This approach allows local Docker builds to access private GAR resources securely, ensuring that credentials are handled appropriately and remain protected.