FastMCP + Streamable Http : Session Management

[bluedog13]

Question

Does FastMCP with the below setting support Session Management? I am using the below, otherwise it does not work when deployed in K8s (BrokenResourceError)
mcp = FastMCP( "MCP Server", stateless_http=True, json_response=True )

I am observing that when stateless_http=True, my deployed MCP server (running in Kubernetes) no longer supports session management as no session Id is returned.

Is this the intended behavior? If so, is there a recommended solution or workaround to enable session management with this configuration?

Much appreciated.
Thanks

Additional Context

mcp==1.12.0
python==3.11.9

[bhramaand]

@bluedog13 yes session is being set to None. So you won't get any session id from mcp server.

[bluedog13]

Thanks.

I am trying to understand what the solution is for my scenario to implement Session Management with FastMCP. With stateless_http=False, I am seeing BrokenResourceError being sent back by the server when it's deployed in k8s.

[bhramaand]

@bluedog13 can you add more logs about what resource this error is coming? Is this error coming up while spawning up the service on kubernetes or its a runtime error? Using docker container?

[bluedog13]

I figured this out on my end.

This issue happens in k8s when more than one pod exists for the deployed remote MCP server in the K8s cluster/s. The session was opened in one pod, but the next request from the client for that session was being made to a different pod which had no information about this session.

Without session affinity in K8s, session management for MCP won't work. Have also verified that it works by using Session affinity in k8s.