hi @Marvin facing this issue while runing flows: Failed to submit flow run '68b4c50f-e64d-4cff-b3df-58062a867912' to infrastructure. urllib3.exceptions.URLSchemeUnknown: Not supported URL scheme http+docker During handling of the above exception, another exception occurred: Traceback (most recent call last): requests.exceptions.InvalidURL: Not supported URL scheme http+docker During handling of the above exception, another exception occurred: File "/home/user/.local/lib/python3.9/site-packages/docker/api/client.py", line 221, in _retrieve_server_version raise DockerException( docker.errors.DockerException: Error while fetching server API version: Not supported URL scheme http+docker The above exception was the direct cause of the following exception: File "/home/user/.local/lib/python3.9/site-packages/prefect_docker/worker.py", line 502, in _get_client raise RuntimeError("Could not connect to Docker.") from exc RuntimeError: Could not connect to Docker.

Oh, what a wonderful and never-ending cascade of misery. It seems you're having issues with Docker while trying to run Prefect flows. The specific error indicates that Prefect cannot connect to Docker, largely because of an unsupported URL scheme

http+docker

. Let’s break this down: 1. URL Scheme

http+docker

Not Supported: The error occurs because the URL scheme

http+docker

is not recognized. This is likely due to a misconfiguration in your Docker client setup. 2. Root Cause: Prefect is trying to connect to Docker but fails due to the aforementioned issue. Let's try to figure out what's gone wrong. ### Steps to Resolve 1. Verify Docker is Running: Ensure Docker is running on your machine. You can do this by executing:

bash
    docker ps

If Docker is not running, start it and try again. 2. Check Docker URL Configuration: Make sure that the Docker URL is correctly configured. The Docker client should be able to connect to the Docker daemon using a proper scheme. Validate your Docker environment variables:

bash
    echo $DOCKER_HOST
    echo $DOCKER_TLS_VERIFY
    echo $DOCKER_CERT_PATH

If these are set incorrectly, you will need to adjust them. Typically,

$DOCKER_HOST

should start with

tcp://

,

unix://

,

npipe://

, or a proper URL scheme. 3. Docker Python SDK: Verify that the Docker Python SDK is correctly installed and updated. You can install or update it using pip:

bash
    pip install --upgrade docker

4. Prefect Docker Worker Configuration: Review the configuration of the Prefect Docker Worker to ensure it is set up to communicate with Docker properly. ### Documentation Search Let me search the Prefect documentation and GitHub issues to see if there are any solutions or discussions related to your error. I'll perform the searches now. It appears there are some recurring errors when Prefect is attempting to interact with Docker. Here are the key findings from the documentation and GitHub issues search: 1. Common Docker Connection Issues: A similar problem was reported where the inability to connect to Docker was due to improperly configured URLs. - GitHub Issue #13478 - Ensure Docker is running (

docker ps

). 2. Docker URL Scheme: The URL scheme

http+docker

is not supported by urllib3, resulting in a

URLSchemeUnknown

error. This indicates a misconfiguration in the Docker client URL setup. - You should check and configure Docker endpoint settings properly. Usually, the Docker socket is accessible via

unix:///var/run/docker.sock

or a TCP endpoint like

<tcp://localhost:2375>

. - Documentation on Docker Worker. 3. Prefect and Docker Communication Setup: Prefect's Docker infrastructure setup requires proper client configuration: - Ensure your

DOCKER_HOST

,

DOCKER_TLS_VERIFY

, and

DOCKER_CERT_PATH

environment variables are correctly set. - Example configuration:

bash
     export DOCKER_HOST='<tcp://localhost:2375>' # Or the appropriate URL
     export DOCKER_TLS_VERIFY=1
     export DOCKER_CERT_PATH='/path/to/certs'

### Suggested Steps to Resolve: 1. Verify Docker is Running: Ensure Docker is running and accessible:

bash
   docker ps

2. Check Docker Environment Variables: Verify that you have setup the Docker-related environment variables correctly:

bash
   echo $DOCKER_HOST
   echo $DOCKER_TLS_VERIFY
   echo $DOCKER_CERT_PATH

Adjust them as needed. 3. Update Docker SDK: Ensure the Docker Python SDK is installed and up-to-date:

bash
   pip install --upgrade docker

4. Prefect Docker Worker Configuration: Ensure that Docker client in Prefect is properly configured: - Documentation: Prefect Docker Worker