When an application (Application A) in Kubernetes relies on a Service name to connect to another application (Application B), and the pods backing that Service become unavailable without a quick recovery, connectivity fails. To restore service without altering Application A's connection method, you can redirect traffic to an external application (Application C) outside the cluster by modifying the Service's endpoints.

1. Backup Original Service and Endpoint Configurations

First, export the current Service and Endpoint resources as YAML files for backup.

kubectl -n default get svc backend-svc -o yaml > backend-svc-original.yaml
kubectl -n default get ep backend-svc -o yaml > backend-svc-endpoints-original.yaml

cp backend-svc-original.yaml backend-svc-modified.yaml
cp backend-svc-endpoints-original.yaml backend-svc-endpoints-modified.yaml

2. Remove and Replace the Original Seervice

Delete the existing Service to detach it from the faulty pods, then update the backup YAML to reference the external application.

kubectl -n default delete svc backend-svc
vim backend-svc-modified.yaml

Apply the modified Service configuration.

kubectl -n default apply -f backend-svc-modified.yaml

3. Create a New Service with the Original Name

Construct a new Service using the same name that Application A expects, but configure it to point to the external application via endpoints.

apiVersion: v1
kind: Service
metadata:
  name: backend-svc
  namespace: default
spec:
  clusterIP: None
  ports:
  - name: web
    port: 80
    protocol: TCP
    targetPort: 80
---
apiVersion: v1
kind: Endpoints
metadata:
  name: backend-svc
  namespace: default
subsets:
- addresses:
  - ip: 192.168.1.251
  ports:
  - name: web
    port: 3389
    protocol: TCP

Apply the new configuration.

kubectl apply -f backend-svc-new.yaml

After execution, verify the Service and Endpoints reflect the external IP.

kubectl get svc,ep

Output example:

NAME                           TYPE        CLUSTER-IP      EXTERNAL-IP   PORT(S)   AGE
service/kubernetes             ClusterIP   10.96.0.1       <none>        443/TCP   3h12m
service/backend-svc            ClusterIP   None            <none>        80/TCP    76m

NAME                             ENDPOINTS                                   AGE
endpoints/kubernetes             172.17.0.2:6443                             3h12m
endpoints/backend-svc            192.168.1.251:3389                          74m

Application A can now reach the external application at 192.168.1.251:3389 using the unchanged Service name backend-svc.