feat: backport MongoDB sidecar to rc/1.101.0

[yuneng-berri]

TLDR

Problem this solves:

• RC images install MongoDB's driver alongside ordinary LiteLLM dependencies

How it solves it:

• Backport feat: move MongoDB vector search to an optional sidecar (BETA) #40203 to rc/1.101.0
• Move MongoDB connections into an optional sidecar
• Remove PyMongo from SDK extras, images, and CI installation

Clean cherry-pick of merge commit b8d573c5f958bab6d93037d292ea2c5de6ea2899, using its first parent, onto RC base eeb7732fc1. All 16 files applied without conflicts or manual changes. The resulting patch ID matches the original PR's merged patch, and git diff --check passes

User Flow

Before: MongoDB users configure the database connection inside LiteLLM

1. Open https://litellm-domain/vector-stores/ and select Manage Vector Stores
2. Add a MongoDB index with its connection string, database, collection, and embedding model
3. Send POST https://litellm-domain/v1/vector_stores/{index}/search with a query and receive matching document text and scores

After: MongoDB users deploy the optional sidecar and keep search requests unchanged

1. Open https://litellm-domain/vector-stores/ and select Manage Vector Stores
2. Add a MongoDB index with its sidecar URL and key, database, collection, and embedding model
3. Send POST https://litellm-domain/v1/vector_stores/{index}/search with a query and receive matching document text and scores

Relevant issues

Backport of #40203

Linear ticket

Pre-Submission checklist

• Meaningful tests from the original PR are included
• The focused tests covering this backport pass locally
• This PR passes all required CI/CD checks
• This PR is isolated to the MongoDB sidecar backport
• Greptile has independently reviewed this PR's current head at 5/5

Screenshots / Proof of Fix

RC runtime, image, and browser validation have not been run for this backport. The source PR documents its own validation; that evidence does not validate this RC head. This PR is opened as a draft and work pauses after creation as requested

Type

Refactoring, Infrastructure, Test

Caveats

Severe

• Existing MongoDB configurations require a sidecar URL and key
• MongoDB connection strings and TLS files move into the sidecar

Medium

• RC tests, image validation, CI, and current-head review remain pending

Final Attestation

• The tests check the right things, including the edge cases, and regressions in the respective real-world customer use-cases are not possible after this PR

[greptile-apps]

Greptile Summary

This PR moves MongoDB vector-store searches from an in-process PyMongo connection to an authenticated HTTP sidecar

• Removes PyMongo from package extras, images, CI installation, and the lockfile
• Adds sidecar URL, authentication, request validation, response validation, and timeout handling
• Updates the dashboard and tests for sidecar configuration
• Introduces an unconditional compatibility break for existing MongoDB configurations
• Allows retained sidecar credentials to cross provider selections in the dashboard

Confidence Score: 3/5

This PR is not safe to merge until existing configurations have an opt-in migration path and provider switching cannot reuse sidecar credentials

Existing MongoDB configurations are rejected without the required compatibility control, and shared sidecar credentials can be submitted after selecting another provider

Files Needing Attention: litellm/llms/mongodb/vector_stores/transformation.py, ui/litellm-dashboard/src/components/vector_store_providers.tsx, ui/litellm-dashboard/src/app/(dashboard)/vector-stores/_components/VectorStoreForm.tsx

Important Files Changed

Filename	Overview
litellm/llms/mongodb/vector_stores/transformation.py	Replaces direct PyMongo searches with a validated sidecar protocol, but unconditionally rejects the previous configuration contract
litellm/llms/custom_httpx/llm_http_handler.py	Propagates vector-store timeouts and maps transport timeouts through provider-specific errors
ui/litellm-dashboard/src/components/vector_store_providers.tsx	Adds MongoDB sidecar fields using shared form keys that retain values when users switch providers
ui/litellm-dashboard/src/app/(dashboard)/vector-stores/_components/VectorStoreForm.tsx	Removes the direct connection-string field but does not clear shared sidecar credentials during provider changes
pyproject.toml	Removes the obsolete MongoDB SDK extra now that LiteLLM no longer imports PyMongo
tests/test_litellm/llms/mongodb/vector_stores/test_mongodb_transformation.py	Replaces direct-driver tests with sync and async sidecar contract, validation, timeout, and error tests

_{Reviews (1): Last reviewed commit: "feat: backport MongoDB sidecar to rc/1.1..." | Re-trigger Greptile}

[greptile-apps]

Existing configs rejected

Existing mongodb_connection_string configurations now fail unconditionally. This violates the repository directive requiring user-controlled flags for backward-incompatible behavior

Rule Used: What: avoid backwards-incompatible changes without... (source)

Note: If this suggestion doesn't match your team's coding style, reply to this and let me know. I'll remember it for next time!

[greptile-apps]

Credentials cross provider selections

After users enter MongoDB sidecar credentials and switch providers, shared fields retain those values, so the next provider receives incorrect credentials