Add ip mode to external-services for static IP endpoints (#740)

ExternalName services only support DNS names (CNAME records), not
raw IP addresses. Add an ip mode that creates a headless Service +
Endpoints with a static IP, enabling routing to host-network
services like Kind gateway IPs or bare-metal endpoints.

Spec format:
  external-services:
    my-service:
      ip: 172.18.0.1
      port: 8899

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

stack_orchestrator/deploy/k8s/cluster_info.py

@@ -1094,8 +1094,9 @@ class ClusterInfo:
     def get_external_service_resources(self) -> List:
         """Build k8s Services (and Endpoints) for external-services in spec.
 
-        Two modes:
+        Three modes:
         - host mode: ExternalName Service (DNS CNAME to external host)
+        - ip mode: headless Service + Endpoints with a static IP
         - selector mode: headless Service + Endpoints (cross-namespace
           routing to a mock pod, IP discovered at deploy time)
 
@@ -1124,6 +1125,24 @@ class ClusterInfo:
                 )
                 resources.append(svc)
 
+            elif "ip" in config:
+                # Static IP: headless Service + Endpoints with fixed address.
+                # Useful for routing to host-network services (e.g. Kind
+                # host gateway) or any endpoint reachable by raw IP.
+                svc = client.V1Service(
+                    metadata=client.V1ObjectMeta(
+                        name=name,
+                        labels={"app": self.app_name},
+                    ),
+                    spec=client.V1ServiceSpec(
+                        cluster_ip="None",
+                        ports=[client.V1ServicePort(port=port, name=f"port-{port}")],
+                    ),
+                )
+                resources.append(svc)
+                # Endpoints are created in deploy_k8s.py using the
+                # static IP — no pod discovery needed.
+
             elif "selector" in config and "namespace" in config:
                 # Cross-namespace headless Service + Endpoints.
                 # The Endpoints IP is populated in deploy_k8s.py at deploy

stack_orchestrator/deploy/k8s/deploy_k8s.py

@@ -431,6 +431,7 @@ class K8sDeployer(Deployer):
         """Create k8s Services for external-services declared in the spec.
 
         For host mode: ExternalName Service (DNS CNAME).
+        For ip mode: headless Service + Endpoints with static IP.
         For selector mode: headless Service + Endpoints with pod IPs
         discovered from the target namespace.
         """
@@ -461,6 +462,47 @@ class K8sDeployer(Deployer):
                 else:
                     raise
 
+        # Create Endpoints for ip-mode services (static IP)
+        for name, svc_config in ext_services.items():
+            if "ip" not in svc_config:
+                continue
+            if opts.o.dry_run:
+                continue
+
+            ip = svc_config["ip"]
+            port = svc_config.get("port", 443)
+
+            endpoints = client.V1Endpoints(
+                metadata=client.V1ObjectMeta(
+                    name=name,
+                    labels={"app": self.cluster_info.app_name},
+                ),
+                subsets=[
+                    client.V1EndpointSubset(
+                        addresses=[client.V1EndpointAddress(ip=ip)],
+                        ports=[
+                            client.CoreV1EndpointPort(port=port, name=f"port-{port}")
+                        ],
+                    )
+                ],
+            )
+
+            try:
+                self.core_api.create_namespaced_endpoints(
+                    body=endpoints, namespace=self.k8s_namespace
+                )
+                print(f"Created endpoints for '{name}' → {ip}:{port}")
+            except ApiException as e:
+                if e.status == 409:
+                    self.core_api.replace_namespaced_endpoints(
+                        name=name,
+                        namespace=self.k8s_namespace,
+                        body=endpoints,
+                    )
+                    print(f"Updated endpoints for '{name}' → {ip}:{port}")
+                else:
+                    raise
+
         # Create Endpoints for selector-mode services
         for name, svc_config in ext_services.items():
             if "selector" not in svc_config or "namespace" not in svc_config:

stack_orchestrator/deploy/spec.py

@@ -319,6 +319,8 @@ class Spec:
         Each entry maps a service name to its routing config:
         - host mode: {host: "example.com", port: 443}
           → ExternalName k8s Service (DNS CNAME)
+        - ip mode: {ip: "172.18.0.1", port: 8899}
+          → Headless Service + Endpoints with static IP address
         - selector mode: {selector: {app: "foo"}, namespace: "ns", port: 443}
           → Headless Service + Endpoints (cross-namespace routing to mock pod)
         """