Let me help you troubleshoot this connection issue. There are a few potential problems in your Docker Compose configuration: 1. API URL Mismatch: Your external URL (

<http://prefect.example.com|prefect.example.com>

) won't work unless you have: - Proper DNS resolution for

<http://prefect.example.com|prefect.example.com>

- A reverse proxy (like nginx) handling the routing - Port forwarding configured correctly 2. Port Exposure: You haven't exposed any ports in your Docker Compose file. You need to add port mapping for the Prefect server. 3. Network Configuration: The services need to be on the same network to communicate. Here's the corrected version of your Docker Compose file:

yaml
services:
  prefect:
    image: 'prefecthq/prefect:3-latest'
    depends_on:
      postgresql:
        condition: service_healthy
    ports:
      - "4200:4200"  # Add this to expose the port
    environment:
      - 'PREFECT_API_URL=<http://0.0.0.0:4200/api>'  # Changed for direct access
      - 'PREFECT_API_DATABASE_CONNECTION_URL=<postgresql+asyncpg://postgresuser:supersecurepassword@postgresql:5432/${POSTGRES_DB:-prefect}>'
      - 'PREFECT_API_KEY=gyy789uijnbhgvytf67'
      - 'PREFECT_EXPERIMENTAL_WARN=false'
      - 'PREFECT_EXPERIMENTAL_ENABLE_SCHEDULE_CONCURRENCY=false'
      - 'PREFECT_RUNNER_SERVER_ENABLE=false'
      - 'PREFECT_DEFAULT_WORK_POOL_NAME=default'
    command:
      - prefect
      - server
      - start
      - '--host'
      - '0.0.0.0'
      - '--port'
      - '4200'
    healthcheck:
      test:
        - CMD
        - python
        - '-c'
        - "import requests as r;r.get('<http://127.0.0.1:4200/api/health>').raise_for_status()"
      interval: 5s
      timeout: 5s
      retries: 3
    networks:
      - prefect-network  # Add this

  postgresql:
    # ... (your existing postgresql config)
    networks:
      - prefect-network  # Add this

  agent:
    # ... (your existing agent config)
    networks:
      - prefect-network  # Add this

networks:
  prefect-network:    # Add this network definition
    driver: bridge

To make this work with `prefect.example.com`: 1. If you're using this locally for testing, you can access it directly at

<http://localhost:4200>

2. If you need to use

<http://prefect.example.com|prefect.example.com>

, you'll need to: - Set up a reverse proxy (like nginx) to forward requests to the Prefect server - Configure your DNS or local hosts file to resolve

<http://prefect.example.com|prefect.example.com>

- Update the

PREFECT_API_URL

to match your final access URL For a quick test to verify if the server is working: 1. After applying these changes, run

docker compose up

2. Try accessing

<http://localhost:4200>

3. You should see the Prefect UI If you specifically need to use

<http://prefect.example.com|prefect.example.com>

, let me know and I can provide additional configuration steps for setting up a reverse proxy.

Ah, I see the issue now. There are two problems here: 1. CORS (Cross-Origin Resource Sharing) issues indicated by the "access control checks" errors 2. Protocol mismatch - your browser is trying to use HTTPS but the server is running HTTP Here's how to fix your configuration:

yaml
services:
  prefect:
    image: 'prefecthq/prefect:3-latest'
    depends_on:
      postgresql:
        condition: service_healthy
    ports:
      - "4200:4200"
    environment:
      - 'PREFECT_API_URL=<http://prefect.example.com/api>'  # Remove the :4200 port
      - 'PREFECT_UI_API_URL=<http://prefect.example.com/api>'  # Add this line
      - 'PREFECT_SERVER_API_HOST=0.0.0.0'  # Add this line
      - 'PREFECT_API_DATABASE_CONNECTION_URL=<postgresql+asyncpg://postgresuser:supersecurepassword@postgresql:5432/${POSTGRES_DB:-prefect}>'
      - 'PREFECT_API_KEY=gyy789uijnbhgvytf67'
      - 'PREFECT_EXPERIMENTAL_WARN=false'
      - 'PREFECT_EXPERIMENTAL_ENABLE_SCHEDULE_CONCURRENCY=false'
      - 'PREFECT_RUNNER_SERVER_ENABLE=false'
      - 'PREFECT_DEFAULT_WORK_POOL_NAME=default'
    command:
      - prefect
      - server
      - start
      - '--host'
      - '0.0.0.0'
      - '--port'
      - '4200'
    # ... rest of your prefect service config

Additionally, since you're accessing the server through

<http://prefect.example.com|prefect.example.com>

, you'll need to set up a reverse proxy (like nginx) to handle the routing. Here's a sample nginx configuration:

nginx
server {
    listen 80;
    server_name <http://prefect.example.com|prefect.example.com>;

    location / {
        proxy_pass <http://prefect:4200;>
        proxy_set_header Host $host;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header X-Forwarded-Proto $scheme;
        
        # WebSocket support
        proxy_http_version 1.1;
        proxy_set_header Upgrade $http_upgrade;
        proxy_set_header Connection "upgrade";
    }
}

Add this nginx service to your docker-compose:

yaml
services:
  nginx:
    image: nginx:alpine
    ports:
      - "80:80"
    volumes:
      - ./nginx.conf:/etc/nginx/conf.d/default.conf:ro
    depends_on:
      - prefect
    networks:
      - prefect-network

If you need HTTPS (which is recommended for production): 1. Add SSL certificates 2. Update the nginx configuration to listen on port 443 3. Update all

PREFECT_API_URL

and

PREFECT_UI_API_URL

to use

https://

instead of

http://

Try these changes and let me know if you're still experiencing issues. Remember to: 1. Save the nginx configuration in a file named

nginx.conf

in the same directory as your docker-compose file 2. Restart all services with

docker compose down && docker compose up -d

3. Access the UI through

<http://prefect.example.com>

(or

https://

if you've configured SSL)

The error messages indicate that you're accessing the UI over HTTPS (

<https://prefect.example.com>

) but the API endpoints are still being requested over HTTP. This mixed content is being blocked by the browser. Let's fix this by ensuring everything uses HTTPS consistently. Here's the updated configuration: 1. First, update your Prefect service environment variables in docker-compose:

yaml
services:
  prefect:
    environment:
      - 'PREFECT_API_URL=<https://prefect.example.com/api>'
      - 'PREFECT_UI_API_URL=<https://prefect.example.com/api>'
      # ... other environment variables remain the same

2. Update your nginx configuration to handle HTTPS:

nginx
server {
    # Redirect HTTP to HTTPS
    listen 80;
    server_name <http://prefect.example.com|prefect.example.com>;
    return 301 https://$server_name$request_uri;
}

server {
    listen 443 ssl;
    server_name <http://prefect.example.com|prefect.example.com>;

    # SSL configuration
    ssl_certificate /etc/nginx/ssl/cert.pem;
    ssl_certificate_key /etc/nginx/ssl/key.pem;
    ssl_protocols TLSv1.2 TLSv1.3;
    ssl_ciphers HIGH:!aNULL:!MD5;

    location / {
        proxy_pass <http://prefect:4200;>
        proxy_set_header Host $host;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header X-Forwarded-Proto $scheme;
        
        # WebSocket support
        proxy_http_version 1.1;
        proxy_set_header Upgrade $http_upgrade;
        proxy_set_header Connection "upgrade";
    }
}

3. Update your nginx service in docker-compose to include SSL certificates:

yaml
services:
  nginx:
    image: nginx:alpine
    ports:
      - "80:80"
      - "443:443"  # Add HTTPS port
    volumes:
      - ./nginx.conf:/etc/nginx/conf.d/default.conf:ro
      - ./ssl:/etc/nginx/ssl:ro  # Mount SSL certificates
    depends_on:
      - prefect
    networks:
      - prefect-network

4. Update your agent configuration to use HTTPS:

yaml
services:
  agent:
    environment:
      - 'PREFECT_API_URL=<https://prefect.example.com/api>'
      # ... other environment variables remain the same

5. Make sure you have SSL certificates: - Place your SSL certificate files (

cert.pem

and

key.pem

) in an

ssl

directory next to your docker-compose file - If you don't have certificates, you can get free ones from Let's Encrypt using certbot To implement these changes: 1. Create the SSL certificate directory:

bash
mkdir ssl
# Place your cert.pem and key.pem files in this directory

2. Restart your services:

bash
docker compose down
docker compose up -d

3. Check that all services are healthy:

bash
docker compose ps

Important notes: - Make sure your SSL certificates are valid and properly configured - The certificates should match your domain name (

<http://prefect.example.com|prefect.example.com>

) - All URLs in the configuration should consistently use

https://

- If you're using a self-signed certificate for testing, you might need to add it to your browser's trusted certificates Let me know if you need help with any of these steps or if you're still experiencing issues.