RFC: Dynamic webhook middleware for ToolHive #17
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jhrozek
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Jan 15, 2026
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I think this is great, I left some questions inline, but I'd love to see this along with some example webhooks implemented.
Port proposal from toolhive PR #2300. This RFC introduces a dynamic webhook middleware system inspired by Kubernetes admission webhooks, enabling external services to participate in the MCP request pipeline. Signed-off-by: Juan Antonio Osorio <ozz@stacklok.com>
Signed-off-by: Juan Antonio Osorio <ozz@stacklok.com>
- Add HMAC payload signing to Security section (defense-in-depth) - Wrap MCP payload in mcp_request container for mutating webhooks - Add mcp_version field to webhook request formats - Clarify vMCP context fields (server_name vs backend_server) - Add signing_secret_ref to configuration examples - Promote HMAC signing to Phase 1, remove from Phase 3 Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
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Addressed all the feedback! Here's a quick summary:
Thanks for the thorough review @jhrozek! |
jhrozek
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Jan 19, 2026
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Summary
Port proposal from toolhive PR #2300.
Introduces a dynamic webhook middleware system for ToolHive that enables external services to participate in the MCP request pipeline, inspired by Kubernetes admission webhooks.
Problem
Organizations need to integrate ToolHive with existing enterprise systems (policy engines, SIEM, ticketing, HR, CMDB) but currently require forking ToolHive and maintaining custom builds to add new middleware functionality.
Solution
Two new webhook types:
Key Features
--webhook-config webhook.yaml)version: v0.1.0) for evolutionUse Cases
Architecture
Webhooks integrate into existing middleware chain:
Multiple webhooks execute sequentially in configuration order.