2.8. Deploying a load balancer for an application

Procedure

1. Verify that your pods are running by entering the following command:

   $ oc get pods -A

   Example output

   NAMESPACE                            NAME                                                     READY   STATUS   RESTARTS  AGE
   default                              i-06166fbb376f14a8bus-west-2computeinternal-debug-qtwcr  1/1     Running	   0		   46m
   kube-system                          csi-snapshot-controller-5c6586d546-lprv4                 1/1     Running	   0		   51m
   kube-system                          csi-snapshot-webhook-6bf8ddc7f5-kz6k9                    1/1     Running	   0		   51m
   openshift-dns                        dns-default-45jl7                                        2/2     Running	   0		   50m
   openshift-dns                        node-resolver-7wmzf                                      1/1     Running	   0		   51m
   openshift-ingress                    router-default-78b86fbf9d-qvj9s                          1/1     Running 	 0		   51m
   openshift-multus                     dhcp-daemon-j7qnf                                        1/1     Running    0		   51m
   openshift-multus                     multus-r758z                                             1/1     Running    0		   51m
   openshift-operator-lifecycle-manager catalog-operator-85fb86fcb9-t6zm7                        1/1     Running    0		   51m
   openshift-operator-lifecycle-manager olm-operator-87656d995-fvz84                             1/1     Running    0		   51m
   openshift-ovn-kubernetes             ovnkube-master-5rfhh                                     4/4     Running    0		   51m
   openshift-ovn-kubernetes             ovnkube-node-gcnt6                                       1/1     Running    0		   51m
   openshift-service-ca                 service-ca-bf5b7c9f8-pn6rk                               1/1     Running    0		   51m
   openshift-storage                    topolvm-controller-549f7fbdd5-7vrmv                      5/5     Running    0		   51m
   openshift-storage                    topolvm-node-rht2m                                       3/3     Running    0		   50m

2. Create a namespace by running the following commands:

   $ NAMESPACE=<nginx-lb-test> 

   1

   1

   Replace _<nginx-lb-test> with the application namespace that you want to create.

   $ oc create ns $NAMESPACE

   Example namespace

   The following example deploys three replicas of the test nginx application in the created namespace:

   oc apply -n $NAMESPACE -f - <<EOF
   apiVersion: v1
   kind: ConfigMap
   metadata:
     name: nginx
   data:
     headers.conf: |
       add_header X-Server-IP  \$server_addr always;
   ---
   apiVersion: apps/v1
   kind: Deployment
   metadata:
     name: nginx
   spec:
     replicas: 3
     selector:
       matchLabels:
         app: nginx
     template:
       metadata:
         labels:
           app: nginx
       spec:
         containers:
         - image: quay.io/packit/nginx-unprivileged
           imagePullPolicy: Always
           name: nginx
           ports:
           - containerPort: 8080
           volumeMounts:
           - name: nginx-configs
             subPath: headers.conf
             mountPath: /etc/nginx/conf.d/headers.conf
           securityContext:
             allowPrivilegeEscalation: false
             seccompProfile:
               type: RuntimeDefault
             capabilities:
               drop: ["ALL"]
             runAsNonRoot: true
         volumes:
           - name: nginx-configs
             configMap:
               name: nginx
               items:
                 - key: headers.conf
                   path: headers.conf
   EOF

3. You can verify that the three sample replicas started successfully by running the following command:

   $ oc get pods -n $NAMESPACE

4. Create a LoadBalancer service for the nginx test application by running the following command:

   oc create -n $NAMESPACE -f - <<EOF
   apiVersion: v1
   kind: Service
   metadata:
     name: nginx
   spec:
     ports:
     - port: 81
       targetPort: 8080
     selector:
       app: nginx
     type: LoadBalancer
   EOF

   注意

   You must ensure that the port parameter is a host port that is not occupied by other LoadBalancer services or MicroShift components.

5. Verify that the service file exists, that the external IP address is properly assigned, and that the external IP is identical to the node IP by running the following command:

   $ oc get svc -n $NAMESPACE

   Example output

   NAME    TYPE           CLUSTER-IP      EXTERNAL-IP     PORT(S)        AGE
   nginx   LoadBalancer   10.43.183.104   192.168.1.241   81:32434/TCP   2m