Great question. Here’s a Docker Compose setup that runs Prefect Server and a Prefect Kubernetes worker against a local MicroK8s cluster. This assumes Prefect 3.x and Linux (since we use host networking to reach MicroK8s via 127.0.0.1). Before you start: - Make sure MicroK8s is ready and your kubeconfig points to it: -

microk8s status --wait-ready

-

mkdir -p ~/.kube && microk8s config > ~/.kube/config

- Important: MicroK8s kubeconfig usually uses 127.0.0.1 as the API server. The worker uses

network_mode: host

so that 127.0.0.1 resolves to the host (Linux only). If you prefer not to use host networking, update your kubeconfig to use your host IP instead of 127.0.0.1 and remove

network_mode: host

below. docker-compose.yaml:

version: "3.9"

services:
  prefect-server:
    image: prefecthq/prefect:3-latest
    container_name: prefect-server
    command: >
      bash -lc "prefect server start --host 0.0.0.0 --ui"
    ports:
      - "4200:4200"  # API
      - "4433:4433"  # UI
    environment:
      # These help the UI link to the API correctly from your browser
      - PREFECT_UI_URL=<http://localhost:4433>
      - PREFECT_API_URL=<http://localhost:4200/api>
    volumes:
      - prefect_data:/root/.prefect
    restart: unless-stopped

  create-pool:
    image: prefecthq/prefect:3-latest
    depends_on:
      - prefect-server
    environment:
      # Talk to the server via the Docker network
      - PREFECT_API_URL=<http://prefect-server:4200/api>
    command: >
      bash -lc "prefect work-pool create my-k8s --type kubernetes --overwrite"
    restart: "no"

  k8s-worker:
    image: prefecthq/prefect:3-latest
    # The worker needs to reach the MicroK8s API at 127.0.0.1; host networking is the simplest approach on Linux
    network_mode: host
    depends_on:
      - create-pool
    environment:
      # The worker talks to the Prefect API via the host-published port
      - PREFECT_API_URL=<http://localhost:4200/api>
      # Point kubernetes client to the mounted kubeconfig
      - KUBECONFIG=/root/.kube/config
    volumes:
      # Mount your host kubeconfig (created from microk8s config)
      - ~/.kube/config:/root/.kube/config:ro
    command: >
      bash -lc "pip install --no-cache-dir 'prefect[kubernetes]' && prefect worker start -p my-k8s"
    restart: unless-stopped

volumes:
  prefect_data:

How to use: 1) Start everything:

docker compose up -d

2) Open the UI at http://localhost:4433 and confirm: - Work Pools → “my-k8s” exists (created by the create-pool init container) - Workers → a worker is online for “my-k8s” 3) Deploy flows to the pool: - Use

flow.from_source(...).deploy(work_pool_name="my-k8s", ...)

- Ensure the image for your deployments is pullable by MicroK8s nodes (default Prefect images are fine for a quick start) Notes and tips: - If you don’t want to use host networking for the worker, edit your kubeconfig to replace 127.0.0.1 with your host’s IP (or configure MicroK8s to advertise a non-loopback address), then remove

network_mode: host

and set

PREFECT_API_URL=<http://prefect-server:4200/api>

for the worker. - The compose file installs

prefect[kubernetes]

at container start. For faster restarts, consider building a tiny custom image that already includes the kubernetes extra and use that image in the worker.