Introduce require-oauth flag to comply with OAuth in MCP specification #170
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When this flag is enabled, authorization middleware will be turned on. When this flag is enabled, Derived which is generated based on the client token will not be used.
This commit adds authorization middleware. Additionally, this commit rejects the requests if the bearer token is absent in Authorization header of the request.
Per Model Context Protocol specification, MCP Servers must check the audience field of the token to ensure that they are generated specifically for them. This commits parses the JWT token and asserts that audience is correct and token is not expired.
This commit sends online token verification by sending request to TokenReview endpoint of API Server with the token and expected audience. If API Server returns the status as authenticated, that means this token can be used to generate a new ad hoc token for MCP Server. If API Server returns the status as not authenticated, that means this token is invalid and MCP Server returns 401 to force the client to initiate OAuth flow.
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/hold |
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@manusa this is ready for review, when you have a chance. Thanks. |
manusa
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manusa
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Jul 14, 2025
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Fixes #161
Fixes #160
After the in-depth review of model context protocol specification and pondering about what would be the best approach in Kubernetes, I decided to propose the following path to comply with OAuth in this MCP Server.
This PR proposes the following;
--require-oauthand--authorization-urland--server-url(they are hidden for now)--require-oauthis set, authorization middleware for SSE and Streamable HTTP transport types will be enabled.This middleware basically;
Authorizationheader (if not, returns 401 as defined in protocol)TokenReviewrequest to API Server to validate the token online. Result ofTokenReviewis embedded into context of the HTTP Calls.IfMCP Server serves--require-oauthis set,.well-known/oauth-protected-resourceendpoint to serve the authorization url of the cluster. Authorization url can be specified via toml configuration or flag. If it is unspecified, API Server host name defined in the MCP Kubeconfig will be used.