This is a demo Python server written with FastAPI. The server connects to PostgreSQL and exposes Prometheus metrics.

The server is packaged as a "rock" using Canonical's OCI-compliant format for container images.

Build and run the container image

You'll need Rockcraft and Docker.

By default, Docker requires sudo. To use Docker as a regular user, run sudo usermod -aG docker $USER then log out and log back in again.

1. Build the container image from source:

   rockcraft pack
   

   This creates a .rock file. The name of the .rock file depends on your system architecture.

2. Make the container image available to Docker:

   rockcraft.skopeo --insecure-policy \
       copy "oci-archive:<rock>" "docker-daemon:api-demo-server:integration"
   

   Where <rock> is the path to the .rock file.

3. Run the container image alongside PostgreSQL:

   docker compose up
   

4. In a separate terminal, check that the server is available:

   curl http://localhost:8000/version
   

   This returns a JSON object that contains the server's version number.

The server has several other API endpoints, including:

• API docs - http://localhost:8000/docs
• Prometheus metrics - http://localhost:8000/metrics

Run automated tests

If you modify the server, rebuild the container image and run the PostgreSQL integration tests:

rockcraft pack
make integration

The integration tests require Docker.

Alternatively, run rockcraft test. This builds the container image and runs the integration tests inside a LXD container. It's slower, but you don't need Docker on your system.

Server environment variables

• DEMO_SERVER_LOGFILE - Path to the file where logs should be written
• DEMO_SERVER_DB_HOST - IP address of the database host
• DEMO_SERVER_DB_PORT - Port of the database host
• DEMO_SERVER_DB_USER - Username that has access to the database
• DEMO_SERVER_DB_PASSWORD - Password for the DEMO_SERVER_DB_USER user

Deploy the container image as a Juju charm

See From zero to hero: Write your first Kubernetes charm