Deploy the local service mirror only in flat mode

[GTRekter]

Problem

We are currently deploying the local-service-mirror resources in Gateway mode, even though these resources are strictly related to federated services.

Solution

Make the deployment of resources related to local-service-mirror conditional based on gateway.enabled. If gateway.enabled exists and is set to true, skip deploying these resources.

Validation

1. k3d-01 cluster: Deploy the following application

apiVersion: v1
kind: Namespace
metadata:
  name: simple-app
  annotations:
    linkerd.io/inject: enabled
---
apiVersion: v1
kind: Service
metadata:
  name: simple-app-v1
  namespace: simple-app
spec:
  selector:
    app: simple-app-v1
    version: v1
  ports:
    - port: 80
      targetPort: 5678
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: simple-app-v1
  namespace: simple-app
spec:
  replicas: 1
  selector:
    matchLabels:
      app: simple-app-v1
      version: v1
  template:
    metadata:
      labels:
        app: simple-app-v1
        version: v1
    spec:
      containers:
        - name: http-app
          image: hashicorp/http-echo:latest
          args:
            - "-text=Simple App v1 - CLUSTER_NAME"
          ports:
            - containerPort: 5678

2. k3d-02 cluster: Deploy the following Namespace resource

apiVersion: v1
kind: Namespace
metadata:
  name: simple-app
  annotations:
    linkerd.io/inject: enabled

3. k3d-01 cluster: Install Linkerd multicluster with the following values

helm upgrade --install multicluster --version 2.18.1 --namespace linkerd-multicluster --create-namespace --set "gateway.enabled=true" --set "controllers[0].link.ref.name=k3d-02" ./Repositories/linkerd-enterprise-multicluster/

4. k3d-02 cluster: Install Linkerd multicluster with the following values

helm upgrade --install multicluster --version 2.18.1 --namespace linkerd-multicluster --create-namespace --set "gateway.enabled=true" --set "controllers[0].link.ref.name=k3d-01" ./Repositories/linkerd-enterprise-multicluster/

5. k3d-01 cluster: Link to the k3d-02 cluster, and vice versa

linkerd multicluster link-gen --context=k3d-01 --cluster-name=k3d-01 --gateway=true --api-server-address=https://172.20.0.3:6443 | kubectl --context=k3d-02 apply -f -
linkerd multicluster link-gen --context=k3d-02 --cluster-name=k3d-02 --gateway=true --api-server-address=https://172.20.0.7:6443 | kubectl --context=k3d-01 apply -f -

6. k3d-01 cluster: Verify that the local-service-mirror deployment is absent

kubectl get pods --context=k3d-01 -n linkerd-multicluster 
NAME                                                         READY   STATUS    RESTARTS   AGE
controller-k3d-02-d7c58f459-z2gwx    2/2         Running    0                   30m
linkerd-gateway-55bc8c7df6-s44js       2/2         Running    0                   30m

kubectl get pods --context=k3d-02 -n linkerd-multicluster 
NAME                                                           READY   STATUS    RESTARTS   AGE
controller-k3d-01-68cf8f69b8-klpns      2/2         Running    0                   19m
linkerd-gateway-55bc8c7df6-dkb2g       2/2         Running    0                   27m

7. k3d-01 cluster: Add the mirror.linkerd.io/exported=true label to the simple-app-v1 service

kubectl label svc -n simple-app simple-app-v1 mirror.linkerd.io/exported=true

8. k3d-02 cluster: Validate the presence of the mirrored service

kubectl get svc -n simple-app
NAME                               TYPE        CLUSTER-IP     EXTERNAL-IP   PORT(S)   AGE
simple-app-v1-k3d-01   ClusterIP   10.248.234.7   <none>              80/TCP      21m

9. k3d-02 cluster: Deploy the following traffic generator

apiVersion: apps/v1
kind: Deployment
metadata:
  name: traffic-v2
  namespace: simple-app
  labels:
    app: traffic-v2
spec:
  replicas: 1
  selector:
    matchLabels:
      app: traffic-v2
  template:
    metadata:
      labels:
        app: traffic-v2
    spec:
      containers:
      - name: traffic-v2
        image: curlimages/curl:latest 
        command: ["/bin/sh", "-c"]
        args:
        - |
          while true
          do 
            TIMESTAMP_SEND=$(date '+%Y-%m-%d %H:%M:%S')
            echo "$TIMESTAMP_SEND - Sending request to http://simple-app-v1-k3d-01.simple-app.svc.cluster.local:80"
            RESPONSE=$(curl -s http://simple-app-v1-k3d-01.simple-app.svc.cluster.local:80)
            TIMESTAMP_RESPONSE=$(date '+%Y-%m-%d %H:%M:%S')
            echo "$TIMESTAMP_RESPONSE - RESPONSE: $RESPONSE"
            sleep 0.001
          done

10. k3d-02 cluster: Check the logs and verify that the requests are successful

kubectl logs -n simple-app traffic-v2-65856dfcdb-vgr7f   -c traffic-v2
...
2025-10-14 20:27:53 - RESPONSE: Simple App v1 - CLUSTER_NAME
2025-10-14 20:27:53 - Sending request to http://simple-app-v1-k3d-01.simple-app.svc.cluster.local:80