I have a question about the docs for the `pex_binary.args` option. The annotation says that it should be an

Iterable[str]

, which from my experience with

subprocess.run

means it should be

["arg1", "arg2"]

, but this results in an error from Pex that the args should be a single string. I presume this behavior is intentional, but then does the

pex_binary.args

need to be an iterable? Could it just be a single string? If it needs to be an iterable for typing, I can try to update the docs

Just to make sure you're building up from ground truth as you read Pants code:

jsirois@Gill-Windows:~ $ pex --inject-args Hello --inject-args Nay --inject-args "Moo, Moo" cowsay -c cowsay -o cowsay.pex
jsirois@Gill-Windows:~ $ ./cowsay.pex
  __________________
| Hello Nay Moo, Moo |
  ==================
                  \
                   \
                     ^__^
                     (oo)\_______
                     (__)\       )\/\
                         ||----w |
                         ||     ||
jsirois@Gill-Windows:~ $ pex-tools cowsay.pex info -i2 | jq .inject_args
[
  "Hello",
  "Nay",
  "Moo,",
  "Moo"
]

So you can both pass multiple

--inject-args

and Pex

shlex.split

s each arg you inject.

jsirois@Gill-Windows:~ $ pex --inject-args Hello --inject-args Nay --inject-args '"Moo, Moo"' cowsay -c cowsay -o cowsay.pex
jsirois@Gill-Windows:~ $ ./cowsay.pex
  __________________
| Hello Nay Moo, Moo |
  ==================
                  \
                   \
                     ^__^
                     (oo)\_______
                     (__)\       )\/\
                         ||----w |
                         ||     ||
jsirois@Gill-Windows:~ $ pex-tools cowsay.pex info -i2 | jq .inject_args
[
  "Hello",
  "Nay",
  "Moo, Moo"
]

So from the pants side, how should this behave? Should pants be turning an iterable of strings into multiple

--inject-args

parts for the pex?

That's where I leave off except to say it seems to me the answer should flow from the principle that Pants should never get in the way of using the tools it supports. So however Pants spells it, it should probably be as close as possible to how the tool spells it and allow you to do all the same things. Deviating from that only leads to frustration for end users.

Thanks for clarifying @enough-analyst-54434! I didn’t actually know about multiple

--inject-args

for pex either, so TIL

It would seem that each str in the iterable is mapped to one

--inject-args

to pex: https://github.com/pantsbuild/pants/blob/1aca34961105f98c2dd63addd37f9e5cfc49ee9b/src/python/pants/backend/python/util_rules/pex.py#L586-L587

Target:

pex_binary(
    name="inference-server",
    layout="packed",
    include_tools=True,
    dependencies=["./ackbar/inference_server"],
    platforms=["linux_x86_64-cp-310-cp310"],
    script="uvicorn",
    args=["<http://ackbar.inference_server.app:app|ackbar.inference_server.app:app>", "--host", "0.0.0.0", "--port", "8080"],
)

Error:

pants package src:inference-server
08:26:57.83 [INFO] Initializing scheduler...
08:26:59.05 [INFO] Scheduler initialized.
08:27:00.98 [INFO] Completed: Building 2 requirements for src/inference-server.pex from the 3rdparty/python-lock.txt resolve: fastapi<0.96.0,>=0.95.1, uvicorn[standard]>=0.21.1
08:27:00.99 [ERROR] 1 Exception encountered:

Engine traceback:
  in `package` goal

ProcessExecutionFailure: Process 'Building 2 requirements for src/inference-server.pex from the 3rdparty/python-lock.txt resolve: fastapi<0.96.0,>=0.95.1, uvicorn[standard]>=0.21.1' failed with exit code 2.
stdout:

stderr:
usage: pex [-o OUTPUT.PEX] [options] [-- arg1 arg2 ...]

pex builds a PEX (Python Executable) file based on the given specifications: sources, requirements, their dependencies and other options.
Command-line options can be provided in one or more files by prefixing the filenames with an @ symbol. These files must contain one argument per line.
pex: error: argument --inject-args: expected one argument



Use `--keep-sandboxes=on_failure` to preserve the process chroot for inspection.

I suspect a bug in pants, where

str(injected_arg)

ought to have been

repr(injected_arg)

Try this as work-around:

args=["<http://ackbar.inference_server.app:app|ackbar.inference_server.app:app>", "'--host'", "0.0.0.0", "'--port'", "8080"],

i.e. quote the

--

options

Thanks @curved-television-6568 that workaround worked!

sweet. cc @happy-kitchen-89482