Document sessionAffinity for scaled MCPServers

[danbarr]

Description

Documents the MCPServer sessionAffinity field in redis-session-storage.mdx, explaining how Service-level affinity (routing) and Redis-backed shared session storage (state) work together for scaled deployments, including the ClientIP-behind-NAT caveat. Cross-links the existing Virtual MCP Server scaling guide rather than duplicating it. Verified against the MCPServer CRD schema (enum [ClientIP, None], default ClientIP).

Type of change

• Documentation update

Related issues/PRs

Addresses a gap in #655.

Submitter checklist

Content and formatting

• I have reviewed the content for technical accuracy
• I have reviewed the content for spelling, grammar, and style

Reviewer checklist

Content

• I have reviewed the content for technical accuracy
• I have reviewed the content for spelling, grammar, and style

[vercel]

The latest updates on your projects. Learn more about Vercel for GitHub.

Project	Deployment	Actions	Updated (UTC)
docs-website	Ready	Preview, Comment	Jun 18, 2026 2:40pm

[Copilot]

Pull request overview

This PR updates the Kubernetes Redis session storage guide to document the MCPServer.spec.sessionAffinity field and explain how Service-level routing affinity (connection pinning) interacts with Redis-backed shared session storage when running scaled (multi-replica) MCPServer deployments.

Changes:

• Adds a new “Session affinity and shared session storage” section describing sessionAffinity behavior (ClientIP vs None) for MCPServer.
• Explains the complementary roles of routing affinity (pinning) and Redis session storage (state sharing) for resilience during pod changes/reconnects.
• Adds a NAT/shared-egress caveat and cross-links the existing vMCP scaling guidance instead of duplicating it.

[danbarr]

Superseded by #956.

On review, redis-session-storage.mdx was the wrong home for this. run-mcp-k8s.mdx already owns MCPServer horizontal scaling (proxy/backend replicas, the ClientIP-affinity-vs-Redis relationship, and the NAT caveat), so this PR's section largely duplicated that, while the genuinely new bit, the spec.sessionAffinity field, belonged alongside those scaling knobs. #956 documents the field there instead, distinguishing the proxy Service affinity (spec.sessionAffinity) from the backend routing already covered. This keeps MCPServer consistent with how MCPRemoteProxy and VirtualMCPServer document scaling on their own pages, and leaves the Redis page focused on the session store.