Adding Podman Support to torchx

[KPostOffice]

Hi all, I'm looking into what it would take to add podman support to torchx. This library seemed like it would be a good fit for a drop in replacement for the Docker client. I changed the code to use a podman client if it is present on the users system. However, when testing the changes I ran into errors with the file object that is created on this line. When I pass the resulting fileobj to the build function I get the following error:

  File "python3.8/site-packages/podman/domain/images_build.py", line 88, in build
    shutil.copyfileobj(kwargs["fileobj"], file)
  File "/usr/lib64/python3.8/shutil.py", line 208, in copyfileobj
    fdst_write(buf)
TypeError: write() argument must be str, not bytes

I tried changing the mode of the file that is being copied to to be wb+ as a quick workaround, however it resulted in another error:

podman.errors.exceptions.BuildError: building at STEP " ": Build error: Unknown instruction: "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x
...
&imagebuilder.Step{Env:[]string{"PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"}, Command:"\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\
...

Any suggestions on how to proceed would be much appreciated.

[rhatdan]

@umohnani8 @jwhonce PTAL

[KPostOffice]

I didn't realize that the Podman REST api was compatible with the Docker REST api. I was able to solve my use case by manually setting DOCKER_HOST after running $ podman system service -t 0 tcp://localhost:8889