[server] Passing model_override_args to launch_server via the CLI.

[kevin85421]

Motivation

1. Passing model_override_args to launch_server via the CLI.
2. Add a new function prepare_server_args to make the logic more unit testable.

Closes #591

Modifications

Checklist

• Format your code according to the Contributor Guide.
• Add unit tests as outlined in the Contributor Guide.
• Update documentation as needed, including docstrings or example tutorials.

[kevin85421]

The default value of parse_args when no arguments are passed to the function is sys.argv[1:].

https://github.com/python/cpython/blob/c3ed775899eedd47d37f8f1840345b108920e400/Lib/argparse.py#L1865

[kevin85421]

Where should this test be added in the CI pipeline?

https://github.com/sgl-project/sglang/blob/main/.github/workflows/pr-test.yml?

[merrymercy]

@kevin85421 Add it here

sglang/test/srt/run_suite.py

Lines 6 to 11 in 474317f

	suites = {
	"minimal": [
	"models/test_embedding_models.py",
	"models/test_generation_models.py",
	"sampling/penaltylib",
	"test_chunked_prefill.py",

This "minimal" suite will be run on CI

[kevin85421]

Thanks! Added 3ecf574.

[kevin85421]

--model could be --model-path or --model-override-args.

[merrymercy]

Can you rename --model-override-args to --override-model-args?

In the meanwhile, we can change all --model in the code base to --model-path to avoid future ambiguity

[kevin85421]

Can you rename --model-override-args to --override-model-args?

How about --json-model-override-args, or do you prefer --override-model-args?

In the meanwhile, we can change all --model in the code base to --model-path to avoid future ambiguity

[merrymercy]

Let me know when it is ready for review.

[kevin85421]

@merrymercy I have already removed "WIP" from the PR title. It's ready for another review iteration. Thanks!