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<@ULVA73B9P> Please provide a docker compose file ...
# marvin-ai
j
@Marvin Please provide a docker compose file to run prefect 3 in a docker container
m
Here's a basic 
docker-compose.yaml
file to run Prefect 3 in a Docker container:
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yaml
version: '3.8'

services:
  prefect:
    image: prefecthq/prefect:3.0.0rc2-python3.12
    environment:
      PREFECT_HOME: /data
    command: prefect server start --host 0.0.0.0
    ports:
      - "4200:4200"
    volumes:
      - prefect-data:/data
      - .:/app

volumes:
  prefect-data: {}
To use this setup, you can run the following commands: 1. Start the Prefect service:
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bash
   docker compose up -d
2. Stream the logs if needed:
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bash
   docker compose logs -f
3. Stop the service:
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bash
   docker compose down
Make sure you replace any necessary configuration details with your own, especially if you are using Prefect Cloud. You may need to set the 
PREFECT_API_URL
and 
PREFECT_API_KEY
environment variables accordingly. For further information, you can refer to the Prefect Docker Compose Example.
j
@Marvin Will that container be accessible from my local network?
m
Yes, the configuration provided in the 
docker-compose.yaml
file will expose the Prefect server on port 4200. By binding to 
0.0.0.0
, the server is accessible from any network interface on the host machine, including your local network. Just ensure that your network settings and firewall rules allow traffic on port 4200. If everything is configured correctly, you should be able to access the Prefect server from other devices on your local network by navigating to 
http://<host_machine_ip>:4200
in a web browser.
j
@Marvin I get the following error in the prefect UI when I try to access that page: Can't connect to Server API at http://prefect:4200/api. Check that it's accessible from your machine.
m
This error suggests that the Prefect UI cannot connect to the Prefect server API. The issue might be related to the way Docker networking is set up. The 
prefect
hostname is not resolvable on your local machine because it's internal to the Docker network. To resolve this issue, you can update the Prefect server configuration to use the IP address of the host machine instead of 
prefect
. Here's what you can do: 1. Update the 
docker-compose.yaml
file: Modify the command to include the 
--host
flag with 
0.0.0.0
to ensure it's accessible from outside the container.
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yaml
   services:
     prefect:
       image: prefecthq/prefect:3.0.0rc2-python3.12
       environment:
         PREFECT_HOME: /data
       command: prefect server start --host 0.0.0.0
       ports:
         - "4200:4200"
       volumes:
         - prefect-data:/data
         - .:/app
2. Access the Prefect UI using the host's IP address: When accessing the Prefect UI, use the IP address of the host machine instead of 
prefect
. For example, if your host's IP address is 
192.168.1.10
, navigate to 
<http://192.168.1.10:4200>
in your browser. 3. Check Docker Network Configuration: Ensure that the Docker network is properly configured to allow connections from your local network. By ensuring the server is bound to 
0.0.0.0
and accessing it via the host machine's IP address, you should be able to resolve the connection issue.
j
@Marvin Here is my dockerfile:
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# Use the official Python image with uv pre-installed
FROM <http://ghcr.io/astral-sh/uv:python3.12-bookworm-slim|ghcr.io/astral-sh/uv:python3.12-bookworm-slim>

# Set the working directory
WORKDIR /app

# Set environment variables
ENV UV_SYSTEM_PYTHON=1
ENV PATH="/root/.local/bin:$PATH"

# Copy only the requirements file first to leverage Docker cache
COPY requirements-prefect.txt .

# Install dependencies
RUN --mount=type=cache,target=/root/.cache/uv \
    uv pip install -r requirements-prefect.txt

# Copy the rest of the application code
COPY . .

# Install curl for health checks
RUN apt-get update && apt-get install -y curl && rm -rf /var/lib/apt/lists/*

# Set the entrypoint
ENTRYPOINT ["/bin/bash", "src/deployments/start_prefect.sh"]
docker-compose
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services:
  prefect:
    build:
      context: .
      dockerfile: Dockerfile.prefect
    ports:
      - "4200:4200"
    volumes:
      - prefect_data:/root/.prefect
      - ./src:/app/src
      - ./data:/app/data  # Mount data directory for SQLite database
    environment:
      - PREFECT_SERVER_API_HOST=0.0.0.0
      - PREFECT_UI_URL=<http://prefect:4200/api>
      - PREFECT_API_URL=<http://prefect:4200/api>
    restart: always

volumes:
  prefect_data:
start_prefect.sh
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#!/bin/bash
set -e

echo "Starting Prefect server..."
# Start Prefect server in the background
prefect server start &
SERVER_PID=$!

# Wait for Prefect server to be ready
echo "Waiting for Prefect server to be ready..."
until curl --silent --fail <http://localhost:4200/api/health> &>/dev/null; do
  echo "Waiting for Prefect server to be ready..."
  sleep 5
done

echo "Prefect server is ready. Creating work pool..."
# Create the 'process' work pool
prefect work-pool create "my-pool" --type process --overwrite
echo "Work pool created. Starting worker..."

# Start the worker in the background
prefect worker start --pool "my-pool" &
WORKER_PID=$!

echo "Worker started. Waiting for worker to connect..."
sleep 10

echo "Deploying flows..."
# Deploy flows
cd /app && python src/deployments/deploy_flows.py

echo "Flows deployed. Keeping container running..."
# Monitor processes
while true; do
  if ! kill -0 $SERVER_PID 2>/dev/null; then
    echo "Prefect server process died, restarting..."
    prefect server start &
    SERVER_PID=$!
  fi
  
  if ! kill -0 $WORKER_PID 2>/dev/null; then
    echo "Worker process died, restarting..."
    prefect worker start --pool "my-pool" &
    WORKER_PID=$!
  fi
  
  sleep 30
done
m
Your message was too long by 204 tokens...
j
@Marvin Here is my dockerfile:
Copy code
# Use the official Python image with uv pre-installed
FROM <http://ghcr.io/astral-sh/uv:python3.12-bookworm-slim|ghcr.io/astral-sh/uv:python3.12-bookworm-slim>

# Set the working directory
WORKDIR /app

# Set environment variables
ENV UV_SYSTEM_PYTHON=1
ENV PATH="/root/.local/bin:$PATH"

# Copy only the requirements file first to leverage Docker cache
COPY requirements-prefect.txt .

# Install dependencies
RUN --mount=type=cache,target=/root/.cache/uv \
    uv pip install -r requirements-prefect.txt

# Copy the rest of the application code
COPY . .

# Install curl for health checks
RUN apt-get update && apt-get install -y curl && rm -rf /var/lib/apt/lists/*

# Set the entrypoint
ENTRYPOINT ["/bin/bash", "src/deployments/start_prefect.sh"]
docker-compose
Copy code
services:
  prefect:
    build:
      context: .
      dockerfile: Dockerfile.prefect
    ports:
      - "4200:4200"
    volumes:
      - prefect_data:/root/.prefect
      - ./src:/app/src
      - ./data:/app/data  # Mount data directory for SQLite database
    environment:
      - PREFECT_SERVER_API_HOST=0.0.0.0
      - PREFECT_UI_URL=<http://prefect:4200/api>
      - PREFECT_API_URL=<http://prefect:4200/api>
    restart: always

volumes:
  prefect_data:
m
The issue seems to stem from the use of 
PREFECT_UI_URL
and 
PREFECT_API_URL
being set to 
<http://prefect:4200/api>
, which is not resolvable from outside the Docker network. Here are some adjustments you can make: 1. Update the Environment Variables: Change the 
PREFECT_UI_URL
and 
PREFECT_API_URL
to use 
0.0.0.0
or the host machine's IP address instead of 
prefect
. This ensures they are accessible from your local network. 2. Ensure Proper Entrypoint Configuration: Verify that the 
start_prefect.sh
script correctly starts the Prefect server with the necessary host configuration. It should include a command like 
prefect server start --host 0.0.0.0
. 3. Access the Prefect UI: Use the host machine's IP address in your browser to access the Prefect UI, such as 
http://<host_machine_ip>:4200
. Here's a revised snippet of your `docker-compose.yaml`:
Copy code
yaml
services:
  prefect:
    build:
      context: .
      dockerfile: Dockerfile.prefect
    ports:
      - "4200:4200"
    volumes:
      - prefect_data:/root/.prefect
      - ./src:/app/src
      - ./data:/app/data
    environment:
      - PREFECT_SERVER_API_HOST=0.0.0.0
      - PREFECT_UI_URL=<http://0.0.0.0:4200/api>
      - PREFECT_API_URL=<http://0.0.0.0:4200/api>
    restart: always

volumes:
  prefect_data:
Make sure that your 
start_prefect.sh
script aligns with these settings and that any hardcoded references to 
prefect
are adjusted to use 
0.0.0.0
or the host IP. This should help resolve the connectivity issue.
j
@Marvin my start_prefect.sh script is as follows:
Copy code
#!/bin/bash
set -e

echo "Starting Prefect server..."
# Start Prefect server in the background
prefect server start &
SERVER_PID=$!

# Wait for Prefect server to be ready
echo "Waiting for Prefect server to be ready..."
until curl --silent --fail <http://localhost:4200/api/health> &>/dev/null; do
  echo "Waiting for Prefect server to be ready..."
  sleep 5
done

echo "Prefect server is ready. Creating work pool..."
# Create the 'process' work pool
prefect work-pool create "my-pool" --type process --overwrite
echo "Work pool created. Starting worker..."

# Start the worker in the background
prefect worker start --pool "my-pool" &
WORKER_PID=$!

echo "Worker started. Waiting for worker to connect..."
sleep 10

echo "Deploying flows..."
# Deploy flows
cd /app && python src/deployments/deploy_flows.py

echo "Flows deployed. Keeping container running..."
# Monitor processes
while true; do
  if ! kill -0 $SERVER_PID 2>/dev/null; then
    echo "Prefect server process died, restarting..."
    prefect server start &
    SERVER_PID=$!
  fi
  
  if ! kill -0 $WORKER_PID 2>/dev/null; then
    echo "Worker process died, restarting..."
    prefect worker start --pool "my-pool" &
    WORKER_PID=$!
  fi
  
  sleep 30
done
m
Your 
start_prefect.sh
script seems generally well-structured, but there are a few adjustments you can make to ensure the Prefect server is accessible from outside the container: 1. Use 
0.0.0.0
for Binding: Ensure that the Prefect server is started with the 
--host 0.0.0.0
option. This will allow connections from any network interface. 2. Correct the 
curl
Command: When checking for the server's readiness, use 
<http://localhost:4200/api/health>
inside the container. However, ensure that the server is bound to 
0.0.0.0
so it can also be accessed externally. Here's a revised version of your script with these considerations:
Copy code
bash
#!/bin/bash
set -e

echo "Starting Prefect server..."
# Start Prefect server in the background
prefect server start --host 0.0.0.0 &
SERVER_PID=$!

# Wait for Prefect server to be ready
echo "Waiting for Prefect server to be ready..."
until curl --silent --fail <http://localhost:4200/api/health> &>/dev/null; do
  echo "Waiting for Prefect server to be ready..."
  sleep 5
done

echo "Prefect server is ready. Creating work pool..."
# Create the 'process' work pool
prefect work-pool create "my-pool" --type process --overwrite
echo "Work pool created. Starting worker..."

# Start the worker in the background
prefect worker start --pool "my-pool" &
WORKER_PID=$!

echo "Worker started. Waiting for worker to connect..."
sleep 10

echo "Deploying flows..."
# Deploy flows
cd /app && python src/deployments/deploy_flows.py

echo "Flows deployed. Keeping container running..."
# Monitor processes
while true; do
  if ! kill -0 $SERVER_PID 2>/dev/null; then
    echo "Prefect server process died, restarting..."
    prefect server start --host 0.0.0.0 &
    SERVER_PID=$!
  fi
  
  if ! kill -0 $WORKER_PID 2>/dev/null; then
    echo "Worker process died, restarting..."
    prefect worker start --pool "my-pool" &
    WORKER_PID=$!
  fi
  
  sleep 30
done
By binding the server to 
0.0.0.0
and ensuring the health check uses 
localhost
, you should be able to access the Prefect server from outside the Docker container on your local network.
j
@Marvin In my docker compose file, can I omit the environment variables or are they needed?
m
In your 
docker-compose.yaml
file, the environment variables 
PREFECT_SERVER_API_HOST
, 
PREFECT_UI_URL
, and 
PREFECT_API_URL
are not strictly necessary if you're specifying the host binding directly in your 
start_prefect.sh
script with 
--host 0.0.0.0
. However, if you intend to use these environment variables for other parts of your setup or scripts, you might want to keep them. Here's when they are useful: 1. 
PREFECT_SERVER_API_HOST
: If you want to programmatically set the API host address within the container, though it seems redundant with the 
--host
option being used. 2. 
PREFECT_UI_URL
and 
PREFECT_API_URL
: These are typically used to inform other services or scripts within the container of the Prefect server's address. If your application or scripts rely on these variables to determine where to connect to the Prefect API, they should be set correctly. If your scripts or application logic do not reference these environment variables, you can safely omit them. Otherwise, ensure they are set to values that reflect your actual network configuration.
j
@Marvin For the 
PREFECT_UI_URL
 can I set the IP of the machine instead of the container name for external access?
m
Yes, you can set 
PREFECT_UI_URL
to the IP address of the host machine to facilitate external access. This will ensure that any part of your application or scripts that rely on this environment variable will use the correct address to reach the Prefect UI from outside the Docker network. Here's how you can set it in your 
docker-compose.yaml
file:
Copy code
yaml
services:
  prefect:
    build:
      context: .
      dockerfile: Dockerfile.prefect
    ports:
      - "4200:4200"
    volumes:
      - prefect_data:/root/.prefect
      - ./src:/app/src
      - ./data:/app/data
    environment:
      - PREFECT_SERVER_API_HOST=0.0.0.0
      - PREFECT_UI_URL=http://<host_machine_ip>:4200/api
      - PREFECT_API_URL=http://<host_machine_ip>:4200/api
    restart: always

volumes:
  prefect_data:
Replace 
<host_machine_ip>
with the actual IP address of your host machine. This will allow external clients to access the Prefect UI using this IP address.
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