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# What does this PR do? This commit introduces a new FastAPI router-based system for defining API endpoints, enabling a migration path away from the legacy @webmethod decorator system. The implementation includes router infrastructure, migration of the Batches API as the first example, and updates to server, OpenAPI generation, and inspection systems to support both routing approaches. The router infrastructure consists of a router registry system that allows APIs to register FastAPI router factories, which are then automatically discovered and included in the server application. Standard error responses are centralized in router_utils to ensure consistent OpenAPI specification generation with proper $ref references to component responses. The Batches API has been migrated to demonstrate the new pattern. The protocol definition and models remain in llama_stack_api/batches, maintaining clear separation between API contracts and server implementation. The FastAPI router implementation lives in llama_stack/core/server/routers/batches, following the established pattern where API contracts are defined in llama_stack_api and server routing logic lives in llama_stack/core/server. The server now checks for registered routers before falling back to the legacy webmethod-based route discovery, ensuring backward compatibility during the migration period. The OpenAPI generator has been updated to handle both router-based and webmethod-based routes, correctly extracting metadata from FastAPI route decorators and Pydantic Field descriptions. The inspect endpoint now includes routes from both systems, with proper filtering for deprecated routes and API levels. Response descriptions are now explicitly defined in router decorators, ensuring the generated OpenAPI specification matches the previous format. Error responses use $ref references to component responses (BadRequest400, TooManyRequests429, etc.) as required by the specification. This is neat and will allow us to remove a lot of boiler plate code from our generator once the migration is done. This implementation provides a foundation for incrementally migrating other APIs to the router system while maintaining full backward compatibility with existing webmethod-based APIs. Closes: https://github.com/llamastack/llama-stack/issues/4188 ## Test Plan CI, the server should start, same routes should be visible. ``` curl http://localhost:8321/v1/inspect/routes | jq '.data[] | select(.route | contains("batches"))' ``` Also: ``` uv run pytest tests/integration/batches/ -vv --stack-config=http://localhost:8321 ================================================== test session starts ================================================== platform darwin -- Python 3.12.8, pytest-8.4.2, pluggy-1.6.0 -- /Users/leseb/Documents/AI/llama-stack/.venv/bin/python3 cachedir: .pytest_cache metadata: {'Python': '3.12.8', 'Platform': 'macOS-26.0.1-arm64-arm-64bit', 'Packages': {'pytest': '8.4.2', 'pluggy': '1.6.0'}, 'Plugins': {'anyio': '4.9.0', 'html': '4.1.1', 'socket': '0.7.0', 'asyncio': '1.1.0', 'json-report': '1.5.0', 'timeout': '2.4.0', 'metadata': '3.1.1', 'cov': '6.2.1', 'nbval': '0.11.0'}} rootdir: /Users/leseb/Documents/AI/llama-stack configfile: pyproject.toml plugins: anyio-4.9.0, html-4.1.1, socket-0.7.0, asyncio-1.1.0, json-report-1.5.0, timeout-2.4.0, metadata-3.1.1, cov-6.2.1, nbval-0.11.0 asyncio: mode=Mode.AUTO, asyncio_default_fixture_loop_scope=None, asyncio_default_test_loop_scope=function collected 24 items tests/integration/batches/test_batches.py::TestBatchesIntegration::test_batch_creation_and_retrieval[None] SKIPPED [ 4%] tests/integration/batches/test_batches.py::TestBatchesIntegration::test_batch_listing[None] SKIPPED [ 8%] tests/integration/batches/test_batches.py::TestBatchesIntegration::test_batch_immediate_cancellation[None] SKIPPED [ 12%] tests/integration/batches/test_batches.py::TestBatchesIntegration::test_batch_e2e_chat_completions[None] SKIPPED [ 16%] tests/integration/batches/test_batches.py::TestBatchesIntegration::test_batch_e2e_completions[None] SKIPPED [ 20%] tests/integration/batches/test_batches_errors.py::TestBatchesErrorHandling::test_batch_invalid_endpoint[None] SKIPPED [ 25%] tests/integration/batches/test_batches_errors.py::TestBatchesErrorHandling::test_batch_cancel_completed[None] SKIPPED [ 29%] tests/integration/batches/test_batches_errors.py::TestBatchesErrorHandling::test_batch_missing_required_fields[None] SKIPPED [ 33%] tests/integration/batches/test_batches_errors.py::TestBatchesErrorHandling::test_batch_invalid_completion_window[None] SKIPPED [ 37%] tests/integration/batches/test_batches_errors.py::TestBatchesErrorHandling::test_batch_streaming_not_supported[None] SKIPPED [ 41%] tests/integration/batches/test_batches_errors.py::TestBatchesErrorHandling::test_batch_mixed_streaming_requests[None] SKIPPED [ 45%] tests/integration/batches/test_batches_errors.py::TestBatchesErrorHandling::test_batch_endpoint_mismatch[None] SKIPPED [ 50%] tests/integration/batches/test_batches_errors.py::TestBatchesErrorHandling::test_batch_missing_required_body_fields[None] SKIPPED [ 54%] tests/integration/batches/test_batches_errors.py::TestBatchesErrorHandling::test_batch_invalid_metadata_types[None] SKIPPED [ 58%] tests/integration/batches/test_batches.py::TestBatchesIntegration::test_batch_e2e_embeddings[None] SKIPPED [ 62%] tests/integration/batches/test_batches_errors.py::TestBatchesErrorHandling::test_batch_nonexistent_file_id PASSED [ 66%] tests/integration/batches/test_batches_errors.py::TestBatchesErrorHandling::test_batch_malformed_jsonl PASSED [ 70%] tests/integration/batches/test_batches_errors.py::TestBatchesErrorHandling::test_file_malformed_batch_file[empty] XFAIL [ 75%] tests/integration/batches/test_batches_errors.py::TestBatchesErrorHandling::test_file_malformed_batch_file[malformed] XFAIL [ 79%] tests/integration/batches/test_batches_errors.py::TestBatchesErrorHandling::test_batch_retrieve_nonexistent PASSED [ 83%] tests/integration/batches/test_batches_errors.py::TestBatchesErrorHandling::test_batch_cancel_nonexistent PASSED [ 87%] tests/integration/batches/test_batches_errors.py::TestBatchesErrorHandling::test_batch_error_handling_invalid_model PASSED [ 91%] tests/integration/batches/test_batches_idempotency.py::TestBatchesIdempotencyIntegration::test_idempotent_batch_creation_successful PASSED [ 95%] tests/integration/batches/test_batches_idempotency.py::TestBatchesIdempotencyIntegration::test_idempotency_conflict_with_different_params PASSED [100%] ================================================= slowest 10 durations ================================================== 1.01s call tests/integration/batches/test_batches_idempotency.py::TestBatchesIdempotencyIntegration::test_idempotent_batch_creation_successful 0.21s call tests/integration/batches/test_batches_errors.py::TestBatchesErrorHandling::test_batch_nonexistent_file_id 0.17s call tests/integration/batches/test_batches_errors.py::TestBatchesErrorHandling::test_batch_malformed_jsonl 0.12s call tests/integration/batches/test_batches_errors.py::TestBatchesErrorHandling::test_batch_error_handling_invalid_model 0.05s setup tests/integration/batches/test_batches.py::TestBatchesIntegration::test_batch_creation_and_retrieval[None] 0.02s call tests/integration/batches/test_batches_errors.py::TestBatchesErrorHandling::test_file_malformed_batch_file[empty] 0.01s call tests/integration/batches/test_batches_idempotency.py::TestBatchesIdempotencyIntegration::test_idempotency_conflict_with_different_params 0.01s call tests/integration/batches/test_batches_errors.py::TestBatchesErrorHandling::test_file_malformed_batch_file[malformed] 0.01s call tests/integration/batches/test_batches_errors.py::TestBatchesErrorHandling::test_batch_retrieve_nonexistent 0.00s call tests/integration/batches/test_batches_errors.py::TestBatchesErrorHandling::test_batch_cancel_nonexistent ======================================= 7 passed, 15 skipped, 2 xfailed in 1.78s ======================================== ``` --------- Signed-off-by: Sébastien Han <seb@redhat.com> |
||
|---|---|---|
| .. | ||
| batches | ||
| common | ||
| internal | ||
| __init__.py | ||
| agents.py | ||
| benchmarks.py | ||
| conversations.py | ||
| datasetio.py | ||
| datasets.py | ||
| datatypes.py | ||
| eval.py | ||
| files.py | ||
| inference.py | ||
| inspect.py | ||
| models.py | ||
| openai_responses.py | ||
| post_training.py | ||
| prompts.py | ||
| providers.py | ||
| py.typed | ||
| pyproject.toml | ||
| rag_tool.py | ||
| README.md | ||
| resource.py | ||
| router_utils.py | ||
| safety.py | ||
| schema_utils.py | ||
| scoring.py | ||
| scoring_functions.py | ||
| shields.py | ||
| tools.py | ||
| uv.lock | ||
| vector_io.py | ||
| vector_stores.py | ||
| version.py | ||
llama-stack-api
API and Provider specifications for Llama Stack - a lightweight package with protocol definitions and provider specs.
Overview
llama-stack-api is a minimal dependency package that contains:
- API Protocol Definitions: Type-safe protocol definitions for all Llama Stack APIs (inference, agents, safety, etc.)
- Provider Specifications: Provider spec definitions for building custom providers
- Data Types: Shared data types and models used across the Llama Stack ecosystem
- Type Utilities: Strong typing utilities and schema validation
What This Package Does NOT Include
- Server implementation (see
llama-stackpackage) - Provider implementations (see
llama-stackpackage) - CLI tools (see
llama-stackpackage) - Runtime orchestration (see
llama-stackpackage)
Use Cases
This package is designed for:
- Third-party Provider Developers: Build custom providers without depending on the full Llama Stack server
- Client Library Authors: Use type definitions without server dependencies
- Documentation Generation: Generate API docs from protocol definitions
- Type Checking: Validate implementations against the official specs
Installation
pip install llama-stack-api
Or with uv:
uv pip install llama-stack-api
Dependencies
Minimal dependencies:
pydantic>=2.11.9- For data validation and serializationjsonschema- For JSON schema utilities
Versioning
This package follows semantic versioning independently from the main llama-stack package:
- Patch versions (0.1.x): Documentation, internal improvements
- Minor versions (0.x.0): New APIs, backward-compatible changes
- Major versions (x.0.0): Breaking changes to existing APIs
Current version: 0.4.0.dev0
Usage Example
from llama_stack_api.inference import Inference, ChatCompletionRequest
from llama_stack_api.providers.datatypes import ProviderSpec, InlineProviderSpec
from llama_stack_api.datatypes import Api
# Use protocol definitions for type checking
class MyInferenceProvider(Inference):
async def chat_completion(self, request: ChatCompletionRequest):
# Your implementation
pass
# Define provider specifications
my_provider_spec = InlineProviderSpec(
api=Api.inference,
provider_type="inline::my-provider",
pip_packages=["my-dependencies"],
module="my_package.providers.inference",
config_class="my_package.providers.inference.MyConfig",
)
Relationship to llama-stack
The main llama-stack package depends on llama-stack-api and provides:
- Full server implementation
- Built-in provider implementations
- CLI tools for running and managing stacks
- Runtime provider resolution and orchestration
Contributing
See the main Llama Stack repository for contribution guidelines.
License
MIT License - see LICENSE file for details.