ramen-mcp-bridge

A stdio MCP server that forwards every JSON-RPC message to a Ramen worker's ramen.v1.Mcp/Call over gRPC. It exists for MCP clients that can only start a local process (stdio) — Claude Desktop, Cursor, and the reference mcp SDK all speak Streamable HTTP directly against Ramen's edge and don't need it; see Get started for that path instead.

Install

pip install ramen-mcp-bridge        # → ramen-mcp-bridge on PATH
# or: uv tool install ramen-mcp-bridge

Use

Against a local worker (plaintext, no TLS):

RAMEN_MCP_KEY="$KEY" ramen-mcp-bridge --target localhost:8080 --insecure --group demo --zone local

Against a cloud deployment (GCP GKE or AWS EKS) fronted by a load balancer with a publicly-trusted certificate (the default since Ramen v0.5.5 — see deploy/README.md):

ramen-mcp-bridge --target <public-hostname>:443 --tls --key rmk_… --group demo --zone a

--tls alone verifies against your system's CA trust store — nothing to download, no kubectl command. An older cluster still using the self-signed fallback needs its CA pulled once (kubectl -n ramen-system get secret ramen-console-tls -o jsonpath='{.data.tls\.crt}' | base64 -d > ramen-lb.pem) and a --ca ramen-lb.pem flag.

Sign in as yourself (0.2.0)

Instead of a shared rmk_ group key, the bridge can sign you in through the console — with your password, a magic link, or the identity provider the console is configured with (Microsoft Entra ID, Google Workspace, any OIDC issuer). A super admin registers an OAuth client on the console's Config page with the redirect URI http://127.0.0.1/callback (any port) and gives you its client id; your account needs a role in the group (an MCP User is enough):

ramen-mcp-bridge --target <public-hostname>:443 --tls --oauth https://<public-hostname> --client-id <client id> \
  --group demo --zone a

The first run opens your browser on the console's sign-in page (--no-browser prints the URL instead); after you approve, the refresh token is kept in ~/.config/ramen-mcp-bridge/tokens-*.json (mode 0600; %LOCALAPPDATA%\ramen-mcp-bridge on Windows; --token-file to move it) and later runs need no browser until it expires or is revoked. Access tokens are scoped to mcp:<group>:<zone>, refreshed before they expire and after the worker answers UNAUTHENTICATED; every call the worker logs then names your account (user:<id>), not a key. Environment: RAMEN_BRIDGE_OAUTH, RAMEN_BRIDGE_CLIENT_ID, RAMEN_BRIDGE_TOKEN_FILE.

Point an MCP client at it directly:

{"mcpServers": {"ramen-stdio": {"command": "ramen-mcp-bridge",
  "env": {"RAMEN_BRIDGE_TARGET": "<public-hostname>:443", "RAMEN_BRIDGE_TLS": "1",
          "RAMEN_MCP_KEY": "rmk_…", "RAMEN_BRIDGE_GROUP": "demo", "RAMEN_BRIDGE_ZONE": "a"}}}}

Every flag has a RAMEN_BRIDGE_* environment variable equivalent (--target → RAMEN_BRIDGE_TARGET, --tls → RAMEN_BRIDGE_TLS=1, --group → RAMEN_BRIDGE_GROUP, --zone → RAMEN_BRIDGE_ZONE) so the key never has to sit in a client's config file — RAMEN_MCP_KEY (or RAMEN_BRIDGE_KEY) is enough. --health [SERVICE] checks grpc.health.v1 and exits 0 when SERVING, for a liveness probe.

Develop

uv sync --group dev
uv run pytest
./gen_proto.sh   # regenerate src/ramen_proto from proto/ramen/v1/mcp.proto after a proto change

License: BSD-3-Clause, same as ramen.