MCP Gateway

Beta

The Rossoctl organization marks the MCP Gateway as experimental. It is Kuadrant/mcp-gateway, which is a separate project.

Routing operates correctly. Most authentication in the gateway is not implemented. The gateway does not replace the checks that the RossoCortex sidecar makes. Do not use the gateway as your access control boundary.

If each agent holds the address of each tool, you must change every agent when you add a tool. The MCP Gateway gives you one address for all tools. It also adds a prefix to each tool name, so two tools with the same function name do not conflict.

Install the gateway with the --with-mcp-gateway option, or with --with-all.

Confirm that the gateway runs

Envoy runs in the gateway-system namespace:

kubectl -n gateway-system get pods
# mcp-gateway-istio-...   1/1   Running

The controller, the broker and the router run in the mcp-system namespace:

kubectl -n mcp-system get pods
# mcp-broker-router-...   1/1   Running
# mcp-controller-...      1/1   Running

Register a tool

Create two resources. The first is an HTTPRoute that tells Envoy how to reach the tool:

apiVersion: gateway.networking.k8s.io/v1
kind: HTTPRoute
metadata:
  name: weather-tool-route
  namespace: default
  labels:
    mcp-server: "true"        # required: the controller uses this label to find the route
spec:
  parentRefs:
    - name: mcp-gateway
      namespace: gateway-system
  hostnames:
    - "weather-tool.mcp.local"
  rules:
    - matches:
        - path:
            type: PathPrefix
            value: /
      backendRefs:
        - name: weather-tool-mcp
          port: 9090

The host name must match the listener of the gateway. Envoy uses it for internal routing only. It is not a name that a client can resolve.

The second resource is an MCPServerRegistration that tells the broker to include the tool:

apiVersion: mcp.kuadrant.io/v1alpha1
kind: MCPServerRegistration
metadata:
  name: weather-tool-servers
  namespace: default
spec:
  prefix: weather_            # each tool from this server becomes weather_<name>
  targetRef:
    group: gateway.networking.k8s.io
    kind: HTTPRoute
    name: weather-tool-route
    namespace: default

The prefix keeps two tools separate when both have a function with the same name.

Both examples assume that the tool is in the default namespace. Change the namespaces to match your deployment.

Point the agents at the gateway

Set one address on each agent:

MCP_URL=http://mcp-gateway-istio.gateway-system.svc.cluster.local:8080/mcp

For a Deployment that already runs:

kubectl set env deployment/weather-service -n team1 \
  MCP_URL="http://mcp-gateway-istio.gateway-system.svc.cluster.local:8080/mcp"

note

This address will become the default value of MCP_URL after the gateway is stable. You will then not set the variable for each agent.

For an agent that runs in a sandbox

The kubectl set env command does not operate on a Sandbox resource. You must change the specification. The variable must already exist in the env array of the container. If the variable is absent, add it first with kubectl edit sandbox weather-service -n team1.

kubectl get sandbox weather-service -n team1 -o json \
  | jq '(.spec.podTemplate.spec.containers[]
         | select(.name == "agent").env[]
         | select(.name == "MCP_URL")).value =
        "http://mcp-gateway-istio.gateway-system.svc.cluster.local:8080/mcp"' \
  | kubectl apply -f -

A change to the specification does not restart a pod that runs. This is an upstream limitation. Delete the pod:

kubectl delete pod -n team1 -l app.kubernetes.io/name=weather-service

For a tool that needs a credential

Some MCP servers need a token before they give their list of tools. Put the token in a Secret and add a label to the Secret:

kubectl create secret generic slack-server-access-token \
  --from-literal=token="Bearer $ACCESS_TOKEN" \
  --namespace default

kubectl label secret slack-server-access-token mcp.kuadrant.io/credential=true

Then name the Secret in the registration:

spec:
  prefix: slack_
  credentialRef:
    name: slack-server-access-token
    key: token
  targetRef:
    group: gateway.networking.k8s.io
    kind: HTTPRoute
    name: slack-tool-route
    namespace: default

Confirm the registration

Discovery can need as much as 60 seconds.

kubectl get mcpserverregistrations weather-tool-servers -o yaml

Look for a Ready condition:

status:
  conditions:
    - type: Ready
      status: "True"
      reason: Ready
      message: MCPServerRegistration successfully reconciled and validated 1 servers with 2 tools

The message gives the number of servers and the number of tools that the broker found. If the message gives zero tools, the backend or the port in the HTTPRoute is wrong, or the tool needs a credential.

Test the result

Open the chat page of an agent and ask for information that needs a registered tool. You can also forward the port of the gateway and connect the MCP Inspector to it. The MCP Gateway page of the console can start the Inspector for you.