Building docker-aware tasks

[gnilrets]

I would like to write an invoke task that would adjust it's behavior based on whether it's running in a docker container or not.

For example, suppose I had a simple task that ran black formatting:

@task
def format(ctx):
    ctx.run('black myfile.py')

When inv format is run within my docker container, it should simply run black myfile.py. However, if I run inv format on the host machine, I'd like invoke to wrap that command in a docker run statement. Suppose I have some environment variable that I can check to see if I'm running in a container (IS_DOCKER). I could write something like this to accomplish what I want:

@task
def format(ctx):
    if os.environ.get('IS_DOCKER') == '1':
        ctx.run('black myfile.py')
    else:
        ctx.run('docker run --rm my-container "black myfile.py"')

I could probably make this a bit nicer by writing a run run_cmd_maybe_docker method. However, it seems like there should be a more natural invoke-style way to accomplish this using contexts and runners.

[ab623]

I have the same issue. I just have a global variable which detects if i'm in a docker env or now.

I just pass the command like black myfile.py' into a helper function which reads the global variable and constructs and returns the correct command for me, which I pass to the run function.