Add a backend api to support dynamic close&create backends by maobaolong · Pull Request #2622 · LMCache/LMCache

maobaolong · 2026-02-19T11:40:43Z

What this PR does / why we need it:

allow for dynamic management of storage backends. This new functionality provides operators with the flexibility to modify and reconfigure storage solutions, such as switching backend types or updating connectors, without the need to restart the entire serving engine. The changes aim to improve operational agility and reduce downtime during configuration adjustments.

Special notes for your reviewers:

If applicable:

this PR contains user facing changes - docs added
this PR contains unit tests

Signed-off-by: baoloongmao <baoloongmao@tencent.com>

gemini-code-assist · 2026-02-19T11:41:02Z

Summary of Changes

Hello @maobaolong, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request significantly enhances the LMCache system by introducing a set of internal API endpoints that allow for dynamic management of storage backends. This new functionality provides operators with the flexibility to modify and reconfigure storage solutions, such as switching backend types or updating connectors, without the need to restart the entire serving engine. The changes aim to improve operational agility and reduce downtime during configuration adjustments.

Highlights

Dynamic Backend Management API: Introduced new internal API endpoints to dynamically list, close, and create storage backends at runtime without requiring a service restart. This enables flexible configuration changes on the fly.
Runtime Backend Switching: Enabled the ability to switch between different storage configurations, such as migrating from a LocalDiskBackend to a GdsBackend or changing a RemoteBackend connector from filesystem to Redis, through API calls.
StorageManager Enhancements: Added list_backends, close_backend, and create_backends methods to the StorageManager to support the new dynamic management capabilities, including handling existing backends and refreshing internal references.
Comprehensive API Documentation and Testing: Provided detailed documentation for the new dynamic backend management API endpoints, including use-case examples, and added a dedicated test suite to ensure their correct functionality and robustness.

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Changelog

docs/source/internal_api_server/dynamic_backend_management.rst
- Added new documentation for the dynamic backend management API, detailing endpoints for listing, closing, and creating backends.
- Included use-case examples for switching backend types and updating remote connectors.
lmcache/v1/internal_api_server/vllm/backend_api.py
- Implemented new FastAPI routes for /backends to handle GET, DELETE, and POST requests.
- Added logic to interact with the StorageManager for listing, closing, and creating storage backends.
- Included error handling and appropriate HTTP status responses for API operations.
lmcache/v1/storage_backend/storage_manager.py
- Introduced list_backends method to return a dictionary of active backend names and their class types.
- Added close_backend method to safely shut down and remove a specified storage backend.
- Implemented create_backends method to instantiate new backends based on the current configuration, skipping already existing ones and refreshing internal references.
tests/v1/internal_api_server/test_backend_api.py
- Created a new test file with fixtures for mocking StorageManager and LMCacheEngine.
- Added test cases for GET /backends to verify listing functionality and error handling.
- Included test cases for DELETE /backends/{backend_name} to confirm backend closing and removal.
- Developed test cases for POST /backends to validate new backend creation.
- Implemented an end-to-end test simulating the full backend switch workflow (close, update config, create, verify).

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Code Review

This pull request introduces a valuable feature for dynamically managing storage backends at runtime via new internal API endpoints. However, it introduces a critical Remote Code Execution (RCE) vulnerability due to dynamic module loading based on runtime-modifiable configuration, and a medium-severity information leakage vulnerability by exposing detailed exception messages. Additionally, the review focuses on improving API consistency, standardizing on JSONResponse, enhancing error logging for better diagnostics, and utilizing modern Python syntax.

Signed-off-by: baoloongmao <baoloongmao@tencent.com>

sammshen · 2026-02-22T02:44:00Z

NOTE: missing recreate function

should the storage manager init also call the same create_backends()? we should have a CreateStorageBackends and a create_backends()

Signed-off-by: baoloongmao <baoloongmao@tencent.com>

maobaolong · 2026-02-22T03:10:34Z

@sammshen recreate api added. PTAL

Signed-off-by: baoloongmao <baoloongmao@tencent.com>

sammshen

LGTM

chunxiaozheng

lgtm

) * Add a backend api to support dynamic close&create backends Signed-off-by: baoloongmao <baoloongmao@tencent.com> * CreateBackend with skip existing backend parameter Signed-off-by: baoloongmao <baoloongmao@tencent.com> * fix gemini comments Signed-off-by: baoloongmao <baoloongmao@tencent.com> * address comments Signed-off-by: baoloongmao <baoloongmao@tencent.com> * Use create_backends while StorageManager init Signed-off-by: baoloongmao <baoloongmao@tencent.com> --------- Signed-off-by: baoloongmao <baoloongmao@tencent.com>

) * Add a backend api to support dynamic close&create backends Signed-off-by: baoloongmao <baoloongmao@tencent.com> * CreateBackend with skip existing backend parameter Signed-off-by: baoloongmao <baoloongmao@tencent.com> * fix gemini comments Signed-off-by: baoloongmao <baoloongmao@tencent.com> * address comments Signed-off-by: baoloongmao <baoloongmao@tencent.com> * Use create_backends while StorageManager init Signed-off-by: baoloongmao <baoloongmao@tencent.com> --------- Signed-off-by: baoloongmao <baoloongmao@tencent.com> Signed-off-by: shaoxiawjc <wjc2800@163.com>

) * Add a backend api to support dynamic close&create backends Signed-off-by: baoloongmao <baoloongmao@tencent.com> * CreateBackend with skip existing backend parameter Signed-off-by: baoloongmao <baoloongmao@tencent.com> * fix gemini comments Signed-off-by: baoloongmao <baoloongmao@tencent.com> * address comments Signed-off-by: baoloongmao <baoloongmao@tencent.com> * Use create_backends while StorageManager init Signed-off-by: baoloongmao <baoloongmao@tencent.com> --------- Signed-off-by: baoloongmao <baoloongmao@tencent.com> Signed-off-by: Aaron Wu <aaron.wu@dell.com>

Add a backend api to support dynamic close&create backends

c8fb9c4

Signed-off-by: baoloongmao <baoloongmao@tencent.com>

gemini-code-assist Bot reviewed Feb 19, 2026

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maobaolong added 2 commits February 19, 2026 19:51

CreateBackend with skip existing backend parameter

48503c9

Signed-off-by: baoloongmao <baoloongmao@tencent.com>

fix gemini comments

98a2d27

Signed-off-by: baoloongmao <baoloongmao@tencent.com>

maobaolong added the full Run comprehensive tests on this PR label Feb 21, 2026

address comments

14bba89

Signed-off-by: baoloongmao <baoloongmao@tencent.com>

Use create_backends while StorageManager init

f12bfe9

Signed-off-by: baoloongmao <baoloongmao@tencent.com>

sammshen approved these changes Feb 22, 2026

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chunxiaozheng approved these changes Feb 24, 2026

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maobaolong merged commit cb7bc24 into LMCache:dev Feb 24, 2026
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Add a backend api to support dynamic close&create backends#2622

Add a backend api to support dynamic close&create backends#2622
maobaolong merged 5 commits intoLMCache:devfrom
maobaolong:dynamicUpdateBackend

maobaolong commented Feb 19, 2026 •

edited

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maobaolong commented Feb 19, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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maobaolong commented Feb 19, 2026 •

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