Let me help you with this PostgreSQL adapter issue in your Prefect server setup. This is a common challenge when working with PostgreSQL and Docker containers. The issue you're experiencing is related to how

psycopg2

is being installed and the underlying system dependencies. Here are two approaches to resolve this: 1. Recommended Approach: Use the Official Postgres Image as Base Modify your Dockerfile or compose file to use the official Postgres-ready Python image:

dockerfile
FROM python:3.12-slim

# Install system dependencies for psycopg2
RUN apt-get update && apt-get install -y \
    libpq-dev \
    gcc \
    && rm -rf /var/lib/apt/lists/*

# Then install psycopg2-binary
RUN pip install psycopg2-binary

2. Alternative: Modify Your Current Setup If you want to stick with the prefect base image, modify your command to install the required system dependencies first:

yaml
prefect-server:
    image: prefecthq/prefect:3-python3.12
    command: >
      sh -c "apt-get update && apt-get install -y libpq-dev gcc && 
             pip install psycopg2-binary && 
             prefect server start"

A few additional notes about your configuration: 1. The

PREFECT_UI_API_URL

should match your actual domain setup. Make sure the URL is accessible from where your clients will connect. 2. Your Traefik configuration looks good, but the Host rule has some formatting issues. It should be:

yaml
- "traefik.http.routers.prefect.rule=Host(`prefect.nicstack.dev`)"

3. For production environments, consider using a more specific version tag for the Prefect image rather than just

3-python3.12

. 4. The healthcheck is well configured, but you might want to increase the interval slightly if you're running in production. If you're still experiencing issues after implementing these changes, please share: 1. The exact error message you're getting 2. Whether you're using Docker Compose or Docker Swarm 3. The contents of your Dockerfile if you're using one This will help me provide more specific guidance for your setup.

@Marvin i am using the prefecthq/prefect:3-python3.12 on docker swarm - should thus not be sued for server?

Actually, the

prefecthq/prefect:3-python3.12

image is perfectly fine to use for running Prefect Server 3.x in Docker Swarm. However, there are a few important adjustments you should make to your setup: 1. Database Dependencies: Instead of installing

psycopg2-binary

at runtime, you should use a multi-stage build or modify your command to properly install the system dependencies first. Here's the corrected version of your service definition:

yaml
prefect-server:
    image: prefecthq/prefect:3-python3.12
    command: >
      sh -c "apt-get update && 
             apt-get install -y libpq-dev gcc curl && 
             pip install psycopg2-binary && 
             prefect server start"
    environment:
      - PREFECT_API_DATABASE_CONNECTION_URL=${PREFECT_API_DATABASE_CONNECTION_URL}
      - PREFECT_UI_API_URL=<https://prefect.nicstack.dev/api>
      - PREFECT_SERVER_API_HOST=0.0.0.0
    volumes:
      - prefect_data:/root/.prefect
    networks:
      - core_network
    healthcheck:
      test: ["CMD", "curl", "-f", "<http://localhost:4200/api/health>"]
      interval: 30s
      timeout: 10s
      retries: 5
    deploy:
      replicas: 1
      placement:
        constraints: [node.role == manager]
      labels:
        - "traefik.enable=true"
        - "traefik.http.routers.prefect.rule=Host(`prefect.nicstack.dev`)"
        - "traefik.http.routers.prefect.entrypoints=websecure"
        - "traefik.http.routers.prefect.tls.certresolver=letsencrypt"
        - "traefik.http.routers.prefect.middlewares=ad-auth"
        - "traefik.http.services.prefect.loadbalancer.server.port=4200"

Key changes and notes: 1. Added

PREFECT_SERVER_API_HOST=0.0.0.0

to ensure the server listens on all interfaces 2. Added

curl

to the apt-get install list since it's needed for the healthcheck 3. Fixed the Host rule formatting in the Traefik labels 4. Included system dependencies installation before the pip install The image is officially supported for running Prefect Server, and many organizations successfully use it in production. The issues you're experiencing are related to the PostgreSQL adapter installation rather than the base image itself. If you continue to experience issues, please share the exact error message you're seeing, and I can provide more specific guidance.

@Marvin i get 1. Containers 2. / 3. processing_prefect-server.1.p9xyvafp7xhhjaohkhqgmc3qy processing_prefect-server.1.p9xyvafp7xhhjaohkhqgmc3qy e6b783111b52 prefecthq/prefect:3-python3.12 STATUS Exited (3) (1 second ago) File "/usr/local/lib/python3.12/site-packages/alembic/util/pyfiles.py", line 116, in load_python_file module = load_module_py(module_id, path) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/usr/local/lib/python3.12/site-packages/alembic/util/pyfiles.py", line 136, in load_module_py spec.loader.exec_module(module) # type: ignore ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "<frozen importlib._bootstrap_external>", line 999, in exec_module File "<frozen importlib._bootstrap>", line 488, in _call_with_frames_removed File "/usr/local/lib/python3.12/site-packages/prefect/server/database/_migrations/env.py", line 201, in <module> run_async_from_worker_thread(apply_migrations) File "/usr/local/lib/python3.12/site-packages/prefect/utilities/asyncutils.py", line 254, in run_async_from_worker_thread return anyio.from_thread.run(call) ^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/usr/local/lib/python3.12/site-packages/anyio/from_thread.py", line 59, in run return async_backend.run_async_from_thread(func, args, token=token) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/usr/local/lib/python3.12/site-packages/anyio/_backends/_asyncio.py", line 2510, in run_async_from_thread return f.result() ^^^^^^^^^^ File "/usr/local/lib/python3.12/concurrent/futures/_base.py", line 456, in result return self.__get_result() ^^^^^^^^^^^^^^^^^^^ File "/usr/local/lib/python3.12/concurrent/futures/_base.py", line 401, in __get_result raise self._exception File "/usr/local/lib/python3.12/site-packages/anyio/_backends/_asyncio.py", line 2497, in task_wrapper return await func(*args) ^^^^^^^^^^^^^^^^^ File "/usr/local/lib/python3.12/site-packages/prefect/server/database/_migrations/env.py", line 186, in apply_migrations engine = await db_interface.engine() ^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/usr/local/lib/python3.12/site-packages/prefect/server/database/interface.py", line 107, in engine engine = await self.database_config.engine() ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/usr/local/lib/python3.12/site-packages/prefect/server/database/configurations.py", line 294, in engine engine = create_async_engine( ^^^^^^^^^^^^^^^^^^^^ File "/usr/local/lib/python3.12/site-packages/sqlalchemy/ext/asyncio/engine.py", line 121, in create_async_engine return AsyncEngine(sync_engine) ^^^^^^^^^^^^^^^^^^^^^^^^ File "/usr/local/lib/python3.12/site-packages/sqlalchemy/ext/asyncio/engine.py", line 1033, in init raise exc.InvalidRequestError( sqlalchemy.exc.InvalidRequestError: The asyncio extension requires an async driver to be used. The loaded 'psycopg2' is not async. ERROR: Application startup failed. Exiting. Server stopped! (Reading database ... 5% (Reading database ... 10% (Reading database ... 15% (Reading database ... 20% (Reading database ... 25% (Reading database ... 30% (Reading database ... 35% (Reading database ... 40% (Reading database ... 45% (Reading database ... 50% (Reading database ... 55% (Reading database ... 60% (Reading database ... 65% (Reading database ... 70% (Reading database ... 75% (Reading database ... 80% (Reading database ... 85% (Reading database ... 90% (Reading database ... 95% (Reading database ... 100% (Reading database ... 13899 files and directories currently installed.) now

Ah, I see the issue now. The error is because Prefect 3.x uses async database connections, but we're installing the wrong PostgreSQL driver. Instead of

psycopg2-binary

, we need to use

psycopg

(the async version) or

asyncpg

. Here's the corrected service definition:

yaml
prefect-server:
    image: prefecthq/prefect:3-python3.12
    command: >
      sh -c "apt-get update && 
             apt-get install -y libpq-dev gcc curl && 
             pip install asyncpg && 
             prefect server start"
    environment:
      - PREFECT_API_DATABASE_CONNECTION_URL=${PREFECT_API_DATABASE_CONNECTION_URL}
      - PREFECT_UI_API_URL=<https://prefect.nicstack.dev/api>
      - PREFECT_SERVER_API_HOST=0.0.0.0
    volumes:
      - prefect_data:/root/.prefect
    networks:
      - core_network
    healthcheck:
      test: ["CMD", "curl", "-f", "<http://localhost:4200/api/health>"]
      interval: 30s
      timeout: 10s
      retries: 5
    deploy:
      replicas: 1
      placement:
        constraints: [node.role == manager]
      labels:
        - "traefik.enable=true"
        - "traefik.http.routers.prefect.rule=Host(`prefect.nicstack.dev`)"
        - "traefik.http.routers.prefect.entrypoints=websecure"
        - "traefik.http.routers.prefect.tls.certresolver=letsencrypt"
        - "traefik.http.routers.prefect.middlewares=ad-auth"
        - "traefik.http.services.prefect.loadbalancer.server.port=4200"

Key changes: 1. Replaced

psycopg2-binary

with

asyncpg

2. Make sure your

PREFECT_API_DATABASE_CONNECTION_URL

uses the

postgresql+asyncpg://

prefix instead of just

postgresql://

Your connection string should look something like this:

PREFECT_API_DATABASE_CONNECTION_URL=<postgresql+asyncpg://username:password@hostname:5432/database_name>

This should resolve the async driver error you're seeing. The error occurred because Prefect 3.x uses SQLAlchemy's async features, which require an async-compatible database driver.

Based on the research, you should definitely use workers instead of agents in Prefect 3.x. Here's the corrected service definition for your setup:

yaml
prefect-worker:
    image: prefecthq/prefect:3-python3.12
    command: prefect worker start --pool 'your-work-pool-name' --type docker
    environment:
      - PREFECT_API_URL=<http://prefect-server:4200/api>
      # Optional: Configure worker polling interval
      - PREFECT_WORKER_QUERY_SECONDS=15
    volumes:
      - /var/run/docker.sock:/var/run/docker.sock
      - prefect_flows:/opt/prefect/flows
    networks:
      - core_network
      - data_network
    deploy:
      replicas: 1
      placement:
        constraints: [node.role == worker]
      restart_policy:
        condition: on-failure
        delay: 5s

Important notes about workers in Prefect 3.x: 1. Work Pool Creation: - You need to create a work pool before starting the worker - You can create it via the UI or CLI:

bash
   prefect work-pool create 'your-work-pool-name' --type docker

2. Worker Types: - Docker (for container-based deployments) - Process (for local process execution) - Kubernetes (for k8s deployments) 3. Key Differences from Agents: - Workers are more infrastructure-aware - Better handling of concurrent runs - Improved visibility into worker status - Built-in infrastructure management 4. Optional Configuration:

bash
   # Limit concurrent runs
   prefect worker start --pool 'your-work-pool-name' --type docker --limit 5

   # Configure prefetch time
   prefect worker start --pool 'your-work-pool-name' --type docker --prefetch-seconds 30

The server doesn't automatically start workers - you need to explicitly start them. However, you can: 1. Run multiple worker replicas using Docker Swarm's replicas feature 2. Configure auto-scaling using Docker Swarm's update policies 3. Use health checks to automatically restart failed workers Would you like me to provide more specific details about any of these aspects of worker configuration?

Let me help you fix the worker startup issue. For a Docker worker, we need to install the Docker worker package first. Here's the corrected service definition:

yaml
prefect-worker:
    image: prefecthq/prefect:3-python3.12
    command: >
      sh -c "pip install prefect-docker &&
             prefect worker start --pool 'your-work-pool-name' --type docker"
    environment:
      - PREFECT_API_URL=<http://prefect-server:4200/api>
      - PREFECT_WORKER_QUERY_SECONDS=15
      # Add Docker socket path to allow worker to find Docker
      - DOCKER_HOST=unix:///var/run/docker.sock
    volumes:
      - /var/run/docker.sock:/var/run/docker.sock
      - prefect_flows:/opt/prefect/flows
    networks:
      - core_network
      - data_network
    deploy:
      replicas: 1
      placement:
        constraints: [node.role == worker]
      restart_policy:
        condition: on-failure
        delay: 5s

Key changes: 1. Added

pip install prefect-docker

to install the required Docker worker dependency 2. Added

DOCKER_HOST

environment variable to ensure the worker can communicate with Docker 3. Combined commands using

sh -c

to allow for multiple commands Before starting the worker, make sure you've created the work pool:

bash
# Create the Docker work pool first (run this once)
prefect work-pool create 'your-work-pool-name' --type docker

If you're still having issues, please share the full error message you're seeing, and I can provide more specific guidance.