<@ULVA73B9P> When using ECS worker guides and conf...
# ask-marvin
d
@Marvin When using ECS worker guides and configuring the Prefect.yaml file, explain each of the parameters in the deployments section and what I would change for using my own scripts such as below...
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# the deployments section allows you to provide configuration for deploying flows
deployments:
- name: my_ecs_deployment
    version:
    tags: []
    description:
    entrypoint: flow.py:my_flow
    parameters: {}
    work_pool:
        name: ecs-dev-pool
        work_queue_name:
        job_variables:
        image: '{{ build_image.image }}'
    schedules: []
pull:
    - prefect.deployments.steps.set_working_directory:
        directory: /opt/prefect/ecs-worker-guide
m
thought for 64.1 seconds
Let me break down each parameter in the deployments section of your prefect.yaml file and explain how to customize it for your own scripts:
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yaml
deployments:
- name: my_ecs_deployment      # The name of your deployment (change this to something meaningful for your flow)
    version:                   # Optional: Version number for your deployment
    tags: []                  # Optional: List of tags to organize and filter deployments
    description:              # Optional: A description of what your flow does
    entrypoint: flow.py:my_flow  # Path to your flow file and function name (format: "file_path:flow_function_name")
    parameters: {}            # Dictionary of default parameters to pass to your flow
    work_pool:
        name: ecs-dev-pool    # Name of your ECS work pool (must match what you created in Prefect)
        work_queue_name:      # Optional: Specific work queue within the pool
        job_variables:        # Optional: Additional variables for the ECS task
        image: '{{ build_image.image }}'  # Docker image to use (references built image from build section)
    schedules: []            # Optional: List of schedules for automated runs
pull:
    - prefect.deployments.steps.set_working_directory:
        directory: /opt/prefect/ecs-worker-guide  # Working directory inside the container
To customize this for your own scripts, here are the key changes you would make: 1. name: Change
my_ecs_deployment
to a descriptive name for your flow deployment
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yaml
   name: my-custom-etl-flow
2. entrypoint: This is crucial - change to point to your flow file and function:
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yaml
   entrypoint: path/to/your/script.py:your_flow_function
For example, if you have a file
etl_process.py
with a flow function called `process_data`:
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yaml
   entrypoint: etl_process.py:process_data
3. parameters: Add any default parameters your flow needs:
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yaml
   parameters:
     batch_size: 1000
     data_source: "production"
4. work_pool: - `name`: Must match the name of your ECS work pool in Prefect - `image`: Should reference your Docker image
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yaml
   work_pool:
     name: your-ecs-pool
     image: '{{ build_image.image }}'  # Or direct reference like 'your-repo/image:tag'
5. pull/directory: Change the working directory to match your container's structure:
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yaml
   pull:
     - prefect.deployments.steps.set_working_directory:
         directory: /path/to/your/code
Important Notes: 1. The
image
reference
{{ build_image.image }}
assumes you have a build step in your prefect.yaml file. If you're using a pre-built image, you can directly specify it. 2. Make sure your ECS work pool is properly configured in Prefect with the necessary AWS credentials and permissions. 3. The working directory (
directory
) should match the structure inside your Docker container, not your local machine. 4. If you need specific AWS resources or configurations, you can add them under `job_variables`:
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yaml
   job_variables:
     cpu: "256"
     memory: "512"
     task_role_arn: "arn:aws:iam::YOUR_ACCOUNT:role/YOUR_ROLE"
For more detailed information about ECS-specific configurations, you can refer to the Prefect ECS integration guide. Would you like me to explain any specific part in more detail or help you with a specific configuration you're trying to set up?
d
@Marvin What about the
tags
, do those go into the Prefect UI or AWS?
m
thought for 71.0 seconds
Let me clarify about tags in Prefect deployments: The tags specified in the
prefect.yaml
file are Prefect-specific and appear in the Prefect UI - they are not AWS tags. These tags serve several important purposes: 1. Prefect UI Organization: Tags appear in the Prefect UI and help you: - Filter and search for specific deployments - Group related deployments together - Quickly identify deployment types or purposes 2. Deployment Management: You can use tags to:
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yaml
   tags: 
     - "production"
     - "etl"
     - "daily-batch"
3. Flow Control: Tags can be used programmatically to: - Trigger other flows based on tagged runs - Apply concurrency limits to groups of deployments - Filter deployments in code If you need to add AWS tags to your ECS resources, those would be configured separately through: 1. Your ECS task definitions 2. The
job_variables
section of your work pool configuration 3. AWS CLI or Console directly Here's an example showing both Prefect tags and AWS-related configuration:
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yaml
deployments:
- name: my_ecs_deployment
    tags: ["production", "etl"]  # These appear in Prefect UI
    work_pool:
        name: ecs-dev-pool
        job_variables:
            # AWS-specific tags would go in your task definition
            task_tags:
                Environment: Production
                Project: DataPipeline
The key difference is: - Prefect tags: Used for organization and flow control within Prefect - AWS tags: Used for resource management and cost allocation in AWS Would you like me to explain more about how to use tags for specific purposes in Prefect, or would you like to know more about AWS resource tagging in the context of ECS deployments?
d
@Marvin I'm getting the following error which results in me having to manually fill out the deployment segments
m
thought for 4.4 seconds
I notice you mentioned an error but I don't see the actual error message in your message. Could you please share: 1. The exact error message you're receiving 2. When this error occurs (during deployment creation, during execution, etc.) 3. The command you're using when you get this error This will help me provide a more accurate and helpful solution to your specific issue.
d
@Marvin I'm getting the following error which results in me having to manually fill out the deployment segments...
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Unable to read the specified config file. Reason: mapping values are not allowed here
  in "prefect.yaml", line 24, column 12. Skipping.
m
thought for 13.2 seconds
Ah, this is a YAML formatting error! Let me help you understand and fix this issue. The error
mapping values are not allowed here
typically occurs when there's an indentation issue in your YAML file. YAML is very sensitive to indentation, and it must be consistent throughout the file. Here's the correct indentation format for the prefect.yaml file:
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yaml
deployments:
- name: my_ecs_deployment    # Note: single dash with space before 'name'
  version:                   # Two spaces indentation for all properties
  tags: []
  description:
  entrypoint: flow.py:my_flow
  parameters: {}
  work_pool:
    name: ecs-dev-pool      # Four spaces indentation for nested properties
    work_queue_name:
    job_variables:
    image: '{{ build_image.image }}'
  schedules: []
pull:
  - prefect.deployments.steps.set_working_directory:    # Note the dash alignment
      directory: /opt/prefect/ecs-worker-guide         # Six spaces for deeply nested
Common mistakes that cause this error: 1. Using tabs instead of spaces 2. Inconsistent indentation levels 3. Missing spaces after dashes (-) 4. Extra spaces where they shouldn't be Here are the key indentation rules: - Top-level keys (like
deployments
and
pull
) start at column 0 - List items start with "- " (dash and space) - Properties under a list item are indented with 2 spaces from the dash - Nested properties get an additional 2 spaces per level To fix this: 1. Make sure you're using a text editor that: - Shows whitespace characters - Uses spaces instead of tabs - Maintains consistent indentation 2. Common editors that help with YAML: - VS Code (with YAML extension) - PyCharm - Sublime Text 3. You can also validate your YAML using online tools like: - YAML Validator - YAML Lint Would you like to share your current prefect.yaml file? That way, I can help identify the specific indentation issue causing the error.
d
@Marvin Now I'm getting
ValueError: Dockerfile already exists.
for the
build_docker_image
step.
m
thought for 44.2 seconds
There are two ways to resolve this error: 1. Use your existing Dockerfile (Recommended if you have a custom Dockerfile):
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yaml
build:
  - name: build_image
    prefect_docker_build:
      dockerfile: path/to/your/Dockerfile  # Specify path to your existing Dockerfile
      image_name: your-image-name
      tag: latest
2. Remove the existing Dockerfile (Only if you want Prefect to generate one):
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bash
rm Dockerfile  # This will allow Prefect to generate a new one
Here's a complete example of how to configure the build step when you have an existing Dockerfile:
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yaml
build:
  - name: build_image
    prefect_docker_build:
      dockerfile: ./Dockerfile  # Path to your existing Dockerfile
      image_name: your-registry/your-image-name
      tag: latest
      build_context: .
      push: false  # Set to true if you want to push to a registry

deployments:
  - name: my_ecs_deployment
    work_pool:
      name: ecs-dev-pool
      job_variables:
        image: '{{ build_image.image }}'  # References the image built above
Additional options you can consider: 1. Skip building entirely if you already have an image:
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yaml
build: []  # Empty build section

deployments:
  - name: my_ecs_deployment
    work_pool:
      name: ecs-dev-pool
      job_variables:
        image: your-registry/your-image-name:tag  # Direct reference to existing image
2. Use a different directory for the build context:
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yaml
build:
  - name: build_image
    prefect_docker_build:
      dockerfile: ./docker/Dockerfile
      build_context: ./docker
      image_name: your-image-name
Which approach would you prefer? Are you: 1. Using a custom Dockerfile that you want to keep? 2. Happy to let Prefect generate a Dockerfile for you? 3. Already have a built image you want to use? This will help me provide more specific guidance for your situation.
d
@Marvin I do have a Dockerfile present in my directory, but I don't want to remove it, can I just have it ignored?
m
thought for 26.7 seconds
You can use the
dockerfile_path
parameter to specify a different path/name for the generated Dockerfile, which will leave your existing Dockerfile untouched. Here's how to do it:
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yaml
build:
  - name: build_image
    prefect_docker_build:
      dockerfile_path: Dockerfile.prefect  # This will create a new file instead of overwriting
      image_name: your-image-name
      tag: latest
This configuration will: 1. Keep your existing
Dockerfile
untouched 2. Create a new
Dockerfile.prefect
for Prefect's use 3. Use the new file for building the deployment image You might also want to add
Dockerfile.prefect
to your
.gitignore
file to prevent it from being committed:
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# .gitignore
Dockerfile.prefect
Would you like me to explain any other aspects of the build configuration or help you with additional customizations?
d
@Marvin I'm being asked to login with a PAT...
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prefect.utilities.dockerutils.BuildError: creating build container: internal error: unable to copy from source <docker://prefecthq/prefect:3.4.9-python3.13>: initializing source <docker://prefecthq/prefect:3.4.9-python3.13>: unable to retrieve auth token: invalid username/password: unauthorized: your account must log in with a Personal Access Token (PAT) - learn more at <http://docs.docker.com/go/access-tokens|docs.docker.com/go/access-tokens>
m
thought for 10.8 seconds
Ah yes, this error occurs because Docker Hub now requires authentication with a Personal Access Token (PAT) for pulling images. Let me help you resolve this. Here's what you need to do: 1. Create a Docker Hub PAT: - Go to Docker Hub - Click on your username → Account Settings → Security - Click "New Access Token" - Give it a descriptive name (e.g., "prefect-pulls") - Choose "Read-only" access - Copy the token immediately (you won't see it again) 2. Login to Docker using the PAT:
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bash
docker login -u YOUR_DOCKER_USERNAME
- When prompted for password, use the PAT you just created (not your Docker Hub password) 3. Alternative: Use environment variable:
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bash
export DOCKER_USERNAME=your-username
export DOCKER_PASSWORD=your-pat
If you're using this in a CI/CD environment or want to avoid logging in manually, you can add these credentials to your Prefect configuration:
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bash
prefect config set PREFECT_DOCKER_USERNAME=your-username
prefect config set PREFECT_DOCKER_PASSWORD=your-pat
After doing one of these methods, try your deployment again. The error should be resolved. Important Security Notes: 1. Never commit your PAT to version control 2. Use read-only tokens when possible 3. Consider using Docker credential helpers for more secure token storage Would you like me to explain more about setting up Docker authentication in a specific environment, or do you need help with any other aspect of this setup?
d
@Marvin What if I don't have a Docker account/can't use one?
m
thought for 46.2 seconds
Here are your main options in detail: 1. Use AWS ECR (if you're already using AWS):
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yaml
build:
  - name: build_image
    prefect_docker_build:
      image_name: <http://YOUR_AWS_ACCOUNT.dkr.ecr.REGION.amazonaws.com/your-image-name|YOUR_AWS_ACCOUNT.dkr.ecr.REGION.amazonaws.com/your-image-name>
      base_image: python:3.9-slim
      tag: latest
First login to ECR:
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bash
aws ecr get-login-password --region REGION | docker login --username AWS --password-stdin <http://YOUR_AWS_ACCOUNT.dkr.ecr.REGION.amazonaws.com|YOUR_AWS_ACCOUNT.dkr.ecr.REGION.amazonaws.com>
2. Use GitHub Container Registry (if you have a GitHub account):
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yaml
build:
  - name: build_image
    prefect_docker_build:
      image_name: <http://ghcr.io/YOUR_USERNAME/your-image-name|ghcr.io/YOUR_USERNAME/your-image-name>
      base_image: python:3.9-slim
      tag: latest
3. Local-only Development (no registry needed):
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yaml
build:
  - name: build_image
    prefect_docker_build:
      image_name: local-prefect-image
      base_image: python:3.9-slim
      push: false  # Don't try to push to any registry
4. Process-based Deployment (no Docker at all): This approach runs your flows directly in Python processes rather than containers:
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bash
prefect worker start -p process-pool
And in your prefect.yaml:
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yaml
deployments:
  - name: my_deployment
    entrypoint: your_flow.py:flow_function
    work_pool:
      name: process-pool
The best option depends on your specific needs: - If you're using AWS → Use ECR - If you're using GitHub → Use GHCR - If you're just developing locally → Use local-only development - If you want to avoid Docker completely → Use process-based deployment Would you like me to explain any of these options in more detail? Or would you like help setting up one of these specific alternatives?
d
@Marvin I'm using AWS with ECR, what would my prefect.yaml file look like given my ECR repository name is "foo"?
m
Error: status_code: 529, model_name: claude-3-5-sonnet-latest, body: {'type': 'error', 'error': {'type': 'overloaded_error', 'message': 'Overloaded'}}
thought for 109.0 seconds
Here's what your prefect.yaml should look like for an ECR repository named "foo":
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yaml
build:
  - name: build_image
    prefect_docker_build:
      image_name: ${AWS_ACCOUNT_ID}.dkr.ecr.${AWS_REGION}.<http://amazonaws.com/foo|amazonaws.com/foo>
      tag: latest
      dockerfile_path: Dockerfile.prefect  # Optional: if you want to avoid conflicts with existing Dockerfile

deployments:
  - name: my_ecs_deployment
    entrypoint: flow.py:my_flow  # Replace with your actual flow file and function
    work_pool:
      name: ecs-dev-pool  # Your ECS work pool name
      job_variables:
        image: '{{ build_image.image }}'
        # Optional: Add any ECS-specific configurations
        cpu: "256"
        memory: "512"
        # task_role_arn: "arn:aws:iam::${AWS_ACCOUNT_ID}:role/YourTaskRole"  # Uncomment if needed

pull:
  - prefect.deployments.steps.set_working_directory:
      directory: /opt/prefect/flows  # Adjust this path as needed
Before using this configuration: 1. Set environment variables or replace directly in the yaml:
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bash
   export AWS_ACCOUNT_ID="your-account-id"
   export AWS_REGION="your-region"  # e.g., us-east-1
2. Ensure you're logged into ECR:
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bash
   aws ecr get-login-password --region ${AWS_REGION} | docker login --username AWS --password-stdin ${AWS_ACCOUNT_ID}.dkr.ecr.${AWS_REGION}.<http://amazonaws.com|amazonaws.com>
3. Make sure the repository exists:
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bash
   aws ecr describe-repositories --repository-names foo || aws ecr create-repository --repository-name foo
You can also make the configuration more explicit by directly specifying the account ID and region:
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yaml
build:
  - name: build_image
    prefect_docker_build:
      image_name: <http://123456789012.dkr.ecr.us-east-1.amazonaws.com/foo|123456789012.dkr.ecr.us-east-1.amazonaws.com/foo>  # Replace with your actual values
      tag: latest
Additional Options:
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yaml
    prefect_docker_build:
      # Add these if needed:
      platform: "linux/amd64"  # Specify platform if needed
      push: true              # Set to false for local testing
      build_context: "."      # Specify build context
Would you like me to: 1. Explain any specific part of this configuration in more detail? 2. Help with setting up the necessary AWS permissions? 3. Show how to add specific ECS task configurations?
d
@Marvin With this setup, I'm getting the following error...
prefect.utilities.dockerutils.BuildError: creating build container: internal error: unable to copy from source <docker://prefecthq/prefect:3.4.9-python3.13>: initializing source <docker://prefecthq/prefect:3.4.9-python3.13>: unable to retrieve auth token: invalid username/password: unauthorized: incorrect username or password
m
thought for 10.4 seconds
This error is occurring because the build process is still trying to pull the base Prefect image from Docker Hub. Let's modify the configuration to use a public Python base image instead and specify the Python version explicitly. Update your prefect.yaml like this:
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yaml
build:
  - name: build_image
    prefect_docker_build:
      image_name: ${AWS_ACCOUNT_ID}.dkr.ecr.${AWS_REGION}.<http://amazonaws.com/foo|amazonaws.com/foo>
      tag: latest
      python_version: "3.9"  # Or your preferred Python version
      base_image: "python:3.9-slim"  # Using official Python image instead of Prefect image
      dockerfile_path: Dockerfile.prefect

deployments:
  - name: my_ecs_deployment
    entrypoint: flow.py:my_flow
    work_pool:
      name: ecs-dev-pool
      job_variables:
        image: '{{ build_image.image }}'
The key changes are: 1. Added
python_version
specification 2. Changed
base_image
to use the official Python image which doesn't require authentication If you still get authentication errors, you might need to: 1. Clear your Docker build cache:
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bash
docker builder prune -f
2. Verify your ECR authentication is current:
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bash
aws ecr get-login-password --region ${AWS_REGION} | docker login --username AWS --password-stdin ${AWS_ACCOUNT_ID}.dkr.ecr.${AWS_REGION}.<http://amazonaws.com|amazonaws.com>
Let me know if you still encounter any issues after making these changes.
d
@Marvin Now I'm getting a different error...
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14:30:20.608 | WARNING | prefect.utilities.templating - Value for placeholder 'build_image.image' not found in provided values. Please ensure that the placeholder is spelled correctly and that the corresponding value is provided.
1 validation error for RunnerDeployment
job_variables
  Input should be a valid dictionary
    For further information visit <https://errors.pydantic.dev/2.11/v/dict_type>
m
thought for 8.0 seconds
Could you please share the new error message you're getting? This will help me provide a more accurate solution to your specific issue. Without seeing the error, I can only guess at what might be happening. Common errors at this stage might include: 1. ECR permissions issues 2. Image build failures 3. Path/entrypoint issues 4. Work pool configuration problems If you share the exact error message, I can help you troubleshoot the specific issue you're encountering.
thought for 57.6 seconds
Here's the corrected prefect.yaml configuration:
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yaml
build:
  - name: build_image
    prefect_docker_build:
      image_name: ${AWS_ACCOUNT_ID}.dkr.ecr.${AWS_REGION}.<http://amazonaws.com/foo|amazonaws.com/foo>
      tag: latest
      python_version: "3.9"
      base_image: "python:3.9-slim"
      dockerfile_path: Dockerfile.prefect

deployments:
  - name: my_ecs_deployment
    entrypoint: flow.py:my_flow
    work_pool:
      name: ecs-dev-pool
      job_variables: 
        image: ${AWS_ACCOUNT_ID}.dkr.ecr.${AWS_REGION}.<http://amazonaws.com/foo:latest|amazonaws.com/foo:latest>  # Direct reference instead of template
Key changes: 1. Removed the templated reference
{{ build_image.image }}
2. Added direct reference to the ECR image Alternative approach - you can also structure it this way:
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yaml
build:
  - name: build_image
    prefect_docker_build:
      image_name: ${AWS_ACCOUNT_ID}.dkr.ecr.${AWS_REGION}.<http://amazonaws.com/foo|amazonaws.com/foo>
      tag: latest
      python_version: "3.9"
      base_image: "python:3.9-slim"
      dockerfile_path: Dockerfile.prefect

deployments:
  - name: my_ecs_deployment
    entrypoint: flow.py:my_flow
    work_pool:
      name: ecs-dev-pool
    job_configuration:
      image: ${AWS_ACCOUNT_ID}.dkr.ecr.${AWS_REGION}.<http://amazonaws.com/foo:latest|amazonaws.com/foo:latest>
Make sure: 1. Your AWS environment variables are set:
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bash
export AWS_ACCOUNT_ID="your-account-id"
export AWS_REGION="your-region"
2. Or use explicit values:
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yaml
job_variables:
  image: "<http://123456789012.dkr.ecr.us-east-1.amazonaws.com/foo:latest|123456789012.dkr.ecr.us-east-1.amazonaws.com/foo:latest>"  # Replace with your actual values
Try this updated configuration and let me know if you encounter any other issues.
d
@Marvin I can run deployments, but I get the following message at the end...
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Container 'prefect' exited with non-zero exit code 1.
m
thought for 46.0 seconds
Let's check the common causes and solutions for this error: 1. First, enable logging to see what's happening inside the container. Add these to your work pool configuration:
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yaml
deployments:
  - name: my_ecs_deployment
    work_pool:
      name: ecs-dev-pool
      job_variables:
        image: ${AWS_ACCOUNT_ID}.dkr.ecr.${AWS_REGION}.<http://amazonaws.com/foo:latest|amazonaws.com/foo:latest>
        aws_logs_enabled: true
        aws_logs_group: "/prefect/ecs-tasks"  # Or your preferred log group name
        aws_logs_stream_prefix: "prefect-"
2. Check your task definition has enough memory and CPU:
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yaml
    job_variables:
        cpu: "1024"  # 1 vCPU
        memory: "2048"  # 2GB RAM
3. Verify your container's working directory:
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yaml
pull:
  - prefect.deployments.steps.set_working_directory:
      directory: /opt/prefect/flows  # Make sure this matches your Dockerfile
4. Make sure your dependencies are installed. In your Dockerfile:
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dockerfile
FROM python:3.9-slim

WORKDIR /opt/prefect/flows

COPY requirements.txt .
RUN pip install -r requirements.txt

COPY . .
To debug this: 1. Check CloudWatch Logs:
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bash
aws logs get-log-events \
    --log-group-name "/prefect/ecs-tasks" \
    --log-stream-name "your-log-stream"
2. Test locally before deploying:
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bash
docker run -it --rm \
    ${AWS_ACCOUNT_ID}.dkr.ecr.${AWS_REGION}.<http://amazonaws.com/foo:latest|amazonaws.com/foo:latest> \
    python /opt/prefect/flows/your_flow.py
3. Verify your flow runs locally:
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bash
prefect deployment run 'my_ecs_deployment/my-flow'
Could you: 1. Share your flow code? 2. Share your Dockerfile contents? 3. Check CloudWatch logs and share any error messages you see? This would help me provide more specific guidance for fixing the exit code issue. Also, make sure your ECS task role has these permissions:
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json
{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Effect": "Allow",
            "Action": [
                "logs:CreateLogStream",
                "logs:PutLogEvents"
            ],
            "Resource": "*"
        }
    ]
}
Would you like me to help you: 1. Set up CloudWatch logging? 2. Debug your flow locally? 3. Review your Dockerfile or flow code?