[Feature] Add Azure Blob Storage support for RunAI Model Streamer

[hasethuraman]

Purpose

Add Azure Blob Storage (az://) as a supported object storage backend for loading models via the RunAI Model Streamer, alongside the existing S3 and GCS support.

This enables users to load models directly from Azure Blob Storage using:

AZURE_STORAGE_ACCOUNT_NAME=<account> vllm serve az://<container>/<model-path> --load-format runai_streamer

Authentication uses DefaultAzureCredential (supports az login, managed identity, environment variables, etc.).

Changes:

Add az:// to SUPPORTED_SCHEMES in RunAI utils
Add is_azure() helper and include it in is_cloud_storage()
Add azure extra to runai-model-streamer dependency
Bump runai-model-streamer from 0.15.3 to 0.15.6 (minimum version with Azure support)
Update error messages and docstrings to reflect Azure support

Test Plan

Unit tests for URI detection

pytest tests/transformers_utils/test_utils.py::test_is_azure
pytest tests/transformers_utils/test_utils.py::test_is_cloud_storage
pytest tests/model_executor/model_loader/runai_streamer_loader/test_runai_utils.py::test_is_runai_obj_uri

E2E test (requires Azure credentials and AZURE_STORAGE_ACCOUNT_NAME set)

AZURE_STORAGE_ACCOUNT_NAME= vllm serve az:/// --load-format runai_streamer

Test Result

Unit tests — all pass:
test_is_azure: PASSED
test_is_s3: PASSED
test_is_gcs: PASSED
test_is_cloud_storage: PASSED
test_is_runai_obj_uri: PASSED

File listing from Azure Blob Storage:
$ AZURE_STORAGE_ACCOUNT_NAME=harikaito python3 -c "from vllm.transformers_utils.runai_utils import list_safetensors; print('\n'.join(list_safetensors('az://qwen/Qwen2.5-Coder-7B-Instruct')))"

Model config loaded successfully from az:// URI
Architecture resolved as Qwen2ForCausalLM. [max_model_len=32768]
Server initialized and began weight loading via RunAI streamer

---

Essential Elements of an Effective PR Description Checklist

• The purpose of the PR, such as "Fix some issue (link existing issues this PR will resolve)".
• The test plan, such as providing test command.
• The test results, such as pasting the results comparison before and after, or e2e results
• (Optional) The necessary documentation update, such as updating supported_models.md and examples for a new model.
• (Optional) Release notes update. If your change is user facing, please update the release notes draft in the Google Doc.

[gemini-code-assist]

Code Review

This pull request adds support for loading models from Azure Blob Storage using the RunAI Model Streamer. The changes are well-implemented and consistent across the codebase. The dependency runai-model-streamer is correctly updated to a version that supports Azure, and the azure extra is added to all relevant installation configurations, including the Dockerfile, requirements files, and setup.py. The utility functions for detecting storage schemes are updated, and new tests are added to cover the Azure URI format. The documentation and error messages are also updated to reflect the new capability. The changes are correct and I see no issues.

[github-actions]

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[mergify]

Documentation preview: https://vllm--34614.org.readthedocs.build/en/34614/

[omer-dayan]

Looks graet!

Thanks a lot

[noa-neria]

LGTM

[noa-neria]

@DarkLight1337 can you please review?

[DarkLight1337]

LGTM, thanks

[noa-neria]

@hasethuraman may you please set the streamer version to the latest - 0.15.7 ?
This version includes the correct Azure artifacts

[hasethuraman]

Thanks @noa-neria on updating here. Have bumped up the runai version to 0.15.7. Please take a look

[noa-neria]

LGTM, thanks

[mergify]

Hi @hasethuraman, the pre-commit checks have failed. Please run:

uv pip install pre-commit
pre-commit install
pre-commit run --all-files

Then, commit the changes and push to your branch.

For future commits, pre-commit will run automatically on changed files before each commit.

Tip

Is mypy failing?

mypy is run differently in CI. If the failure is related to this check, please use the following command to run it locally:

# For mypy (substitute "3.10" with the failing version if needed)
pre-commit run --hook-stage manual mypy-3.10

[hasethuraman]

Hi @hasethuraman, the pre-commit checks have failed. Please run:

uv pip install pre-commit
pre-commit install
pre-commit run --all-files

Then, commit the changes and push to your branch.

For future commits, pre-commit will run automatically on changed files before each commit.

Tip

Is mypy failing?

mypy is run differently in CI. If the failure is related to this check, please use the following command to run it locally:

# For mypy (substitute "3.10" with the failing version if needed)
pre-commit run --hook-stage manual mypy-3.10

I have not touched kimi_audio.py but precommit is failing for the untouched file. @andrew @DarkLight1337 any pointers?

Run mypy locally for lowest supported Python version................................................Failed
- hook id: mypy-local
- exit code: 1

$ mypy --python-version 3.10 --follow-imports skip
vllm/tool_parsers/abstract_tool_parser.py:70: error: Unexpected keyword argument "json" for "StructuredOutputsParams"  [call-arg]
/home/hsethuraman/.cache/pre-commit/repo66onwee7/py_env-python3.10/lib/python3.10/site-packages/mypy/typeshed/stdlib/builtins.pyi:117: note: "StructuredOutputsParams" defined here
vllm/tokenizers/kimi_audio.py:302: error: Argument 1 of "decode" is incompatible with supertype "vllm.tokenizers.protocol.TokenizerLike"; supertype defines the argument type as "Sequence[int] | int"  [override]
vllm/tokenizers/kimi_audio.py:302: note: This violates the Liskov substitution principle
vllm/tokenizers/kimi_audio.py:302: note: See https://mypy.readthedocs.io/en/stable/common_issues.html#incompatible-overrides
vllm/tokenizers/kimi_audio.py:324: error: Argument 1 of "convert_ids_to_tokens" is incompatible with supertype "vllm.tokenizers.protocol.TokenizerLike"; supertype defines the argument type as "Sequence[int]"  [override]
vllm/tokenizers/kimi_audio.py:324: note: This violates the Liskov substitution principle
vllm/tokenizers/kimi_audio.py:324: note: See https://mypy.readthedocs.io/en/stable/common_issues.html#incompatible-overrides
Found 3 errors in 2 files (checked 760 source files)
$ mypy --python-version 3.10 --follow-imports skip tests
Success: no issues found in 984 source files
$ mypy --python-version 3.10 --follow-imports skip vllm/lora
Success: no issues found in 39 source files
$ mypy --python-version 3.10 --follow-imports skip vllm/model_executor
Success: no issues found in 269 source files

[hasethuraman]

@DarkLight1337 I dont have rights to merge. Required CI build is success. If all good, could you help me to merge this PR?

[mergify]

This pull request has merge conflicts that must be resolved before it can be
merged. Please rebase the PR, @hasethuraman.

https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/working-with-forks/syncing-a-fork