07-federated-nginx-service.md

Federated NGINX Service

This lab will walk you through creating a federated NGINX service using replica sets and services. For more details on how federated replica sets work review the Federated ReplicaSet Requirements & Design Document

Prerequisites

kubectl config use-context federation-cluster

Federated NGINX ReplicaSet

Federated replica sets leverage the same configuration as a non-federated Kubernetes clusters. By default pods created by a replica set are distributed evenly across all configured clusters.

kubectl get clusters

NAME             STATUS    AGE
asia-east1-b     Ready     2m
europe-west1-b   Ready     2m
us-central1-b    Ready     2m
us-east1-b       Ready     2m

The following command will create an nginx replica set and create 4 nginx pods.

kubectl create -f rs/nginx.yaml

Verify

kubectl get rs

NAME      DESIRED   CURRENT   READY     AGE
nginx     4         4         4         33s

List Pods

CLUSTERS="asia-east1-b europe-west1-b us-east1-b us-central1-b"

for cluster in ${CLUSTERS}; do
  echo ""
  echo "${cluster}"
  kubectl --context=${cluster} get pods
done

Output:

asia-east1-b
NAME          READY     STATUS    RESTARTS   AGE
nginx-zpdcn   1/1       Running   0          5m

europe-west1-b
NAME          READY     STATUS    RESTARTS   AGE
nginx-p8hg0   1/1       Running   0          5m

us-east1-b
NAME          READY     STATUS    RESTARTS   AGE
nginx-07ddf   1/1       Running   0          6m

us-central1-b
NAME          READY     STATUS    RESTARTS   AGE
nginx-m3vzb   1/1       Running   0          6m

Federated NGINX ReplicaSet with Preferences

An annotation can be used to control which clusters pods are scheduled to.

apiVersion: extensions/v1beta1
kind: ReplicaSet
metadata:
  name: nginx-us
  annotations:
    federation.kubernetes.io/replica-set-preferences: |
        {
            "rebalance": true,
            "clusters": {
                "us-east1-b": {
                    "minReplicas": 2,
                    "maxReplicas": 4,
                    "weight": 1
                },
                "us-central1-b": {
                    "minReplicas": 2,
                    "maxReplicas": 4,
                    "weight": 1
                }
            }
        }

The following command will create pods only in the us-east1-b and us-central1-b clusters

kubectl create -f rs/nginx-us.yaml

Verify

for cluster in ${CLUSTERS}; do
  echo ""
  echo "${cluster}"
  kubectl --context=${cluster} get pods
done

Notice there are no nginx-us pods running in the europe-west1-b or asia-east1-b clusters:

Federated NGINX Service

Create a federated service object in the federation-cluster context.

kubectl config use-context federation-cluster

kubectl create -f services/nginx.yaml

Wait until the nginx service is propagated across all 4 clusters and the federated service is updated with the details. Currently this can take up to 5 mins to complete.

Verify

Describe the federated nginx service.

kubectl describe services nginx

Name:			nginx
Namespace:		default
Labels:			app=nginx
Selector:		app=nginx
Type:			LoadBalancer
IP:			
LoadBalancer Ingress:	104.155.179.91, 104.199.198.18, 104.196.155.68, 23.251.129.13
Port:			http	80/TCP
Endpoints:		<none>
Session Affinity:	None
No events.

List Services

for cluster in ${CLUSTERS}; do
  echo ""
  echo "${cluster}"
  kubectl --context=${cluster} describe services nginx
done

Name:                   nginx
Namespace:              default
Labels:                 app=nginx
Selector:               app=nginx
Type:                   LoadBalancer
IP:                     10.87.255.25
LoadBalancer Ingress:   XXX.XXX.XXX.XX
Port:                   http	80/TCP
NodePort:               http	30330/TCP
Endpoints:              10.84.1.5:80
Session Affinity:       None

Review Cloud DNS Console

The Federated controller manager creates DNS entries in the configured zone.