@Marvin How do I configure a docker worker to use a specific user within the container when the flow runs. If I preset the user within a custom dockerfile, then the container shows the following user warning: "UserWarning: Failed to create the Prefect home directory at /nonexistent/.prefect" and a related error that "The directory '/nonexistent/.cache/pip' or its parent directory is not owned or is not writable by the current user"

The issue you're experiencing with the Docker worker and user permissions is a common one when running containers as non-root users. The warning and errors you're seeing are related to directory ownership and permissions, specifically for the Prefect home directory and pip cache. To address this, you can take the following steps: 1. Custom Dockerfile User Setup: When you set a specific user in your Dockerfile using the

USER

directive, ensure that the user has the necessary permissions to create and write to directories like

/home/<user>/.prefect

and

/home/<user>/.cache/pip

. 2. Set Environment Variables: You can set environment variables in your Dockerfile to direct Prefect and pip to use directories within the user's home directory. For example:

dockerfile
   ENV PREFECT_HOME=/home/<user>/.prefect
   ENV PIP_CACHE_DIR=/home/<user>/.cache/pip

3. Directory Creation and Permissions: Ensure that these directories are created and have the correct permissions for the user specified in the Dockerfile. This can be done with:

dockerfile
   RUN mkdir -p /home/<user>/.prefect /home/<user>/.cache/pip && \
       chown -R <user>:<user> /home/<user>/.prefect /home/<user>/.cache/pip

4. Prefect Configuration: In your Prefect flow or deployment configuration, ensure that the environment variables are correctly set so that Prefect knows where to look for its home directory. For more detailed guidance, you might want to review the Prefect Docker deployment documentation. If these steps do not resolve the issue, consider checking for any related open issues or discussions in the Prefect GitHub repository.