Handle ENTRYPOINT+CMD in Docker2Singularity

[Flamefire]

Is your feature request related to a problem? Please describe.
A DockerFile can have both ENTRYPOINT and CMD. According to this or that I assume the meaning would be something like "if arguments are given to container run then use those, else use CMD" (Correct me if I'm wrong, I'm no Docker expert)

Describe the solution you'd like
Append CMD to ENTRYPOINT at container runtime if no arguments given

Describe alternatives you've considered
Use ENTRYPOINT or CMD in %runscript and create a %startscript with both if both are given as the combination is usually used for services (see above link)

[vsoch]

Agreed! I ironically just fixed this for (the repository) Docker2Singularity. This I can add to the current PR. Give me a few minutes!

[vsoch]

Oh good point, so you think we should have a Dockerfile ENTRYPOINT/CMD also map to a Singularity startscript? This makes sense, Docker doesn't have the equivalent (and most people would want to start the service associated with the ENTRYPOINT/CMD.

[vsoch]

okay, just added to the PR to also write a startscript, here is an example result:

%runscript
cd $SRC_DIR
exec /code/salad fork "$@"
%startscript
cd $SRC_DIR
exec /code/salad fork "$@"

[vsoch]

This was just merged in #116 https://github.com/singularityhub/singularity-cli/pull/116/files#diff-e984bd9fd64b5f8bde56908d6b24f600R215

[Flamefire]

No this is not what I meant. Consider the following docker file:

ENTRYPOINT [ "bash" ]
CMD [ "/usr/bin/fooExe" ] 

The correct %runscript would be something like:

if [ $* -gt 0 ]; then exec [ "bash", "/usr/bin/fooExe" ]
else exec bash "$@"
fi

My proposal is to use

%runscript
exec bash "$@"

%startscript
exec "bash" "/usr/bin/fooExe" "$@"

Not sure if the latter is wise so best would probably be the if-else approach above to mirror docker behavior.

[vsoch]

Just tested, this would work reasonably. Let's re-open and address this.

[vsoch]

This I believe is also addressed with the updated recipe parser.

[Flamefire]

Can you point me to the test which tests this? Can't find it

[vsoch]

There isn't one, I had just tested it manually. I know, I know, I'm awful. :P The PR was a lot of work and it just slipped my mind.

I'm not sure how you changed the testing, but I can't get it running locally - there is a tmp_dir undefined and a missing fixture? Did you create a dependency on the CI? This is very bad :/

[Flamefire]

Could you add a test then before closing this? This allows to validate that the code does what is designed here.

Do you have a recent pytest installed? I guess you meant tmp_path which is a fixture introduced in pytest 3.9.0