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Common errors

Docker isn't installed or running

What it looks like:

docker.errors.DockerException: Error while fetching server API version: ('Connection aborted.', FileNotFoundError(2, 'No such file or directory'))

How to solve it:

Install and start Docker Engine: https://docs.docker.com/engine/install/

subprocess.run can't find your command

What it looks like:

FileNotFoundError: [Errno 2] No such file or directory: 'docker exec lug-c8eef2d5-adcd-4263-bf67-061b7ea56f68 /bin/sh -c \'echo "Hello, `uname`!"\''

(no output, when you're expecting output)

How to solve it:

  • If you're using subprocess.run, try setting using the shell=True argument. This sets a shell location and accepts string commands as input, just like a terminal.
  • Make sure that the command exists in the Docker image, and if it's not in the $PATH use an absolute reference path.

It runs slowly

What it looks like:

The command runs slower than expected (e.g. 2x longer than before), after factoring in Docker container start time.

How to solve it:

Docker runs Linux containers in a VM on non-Linux machines. If you're using macOS, for example, Lug will run slower than if you're on Linux.

You can get more speed by running remotely with remote=True – under the hood, this uses a Linux machine.

Without running remotely, this can't be solved without changing operating systems. If a Docker replacement comes along that executes across different architectures with no VM, this could be solved!