Kubernetes Cluster Usage Examples
This article presents the following three sample Kubernetes cluster usage examples:
Example 1: Hello World
This example is based on the Hello-World sample scenario, available here (link opens an external web site in a new browser tab/window).
Begin by creating the hello-world service manifest YAML file with HPE Ezmeral Runtime Enterprise annotation.
# kubectl apply -f https://k8s.io/examples/service/access/hello-application.yaml deployment.apps/hello-world created # kubectl get deployments hello-world NAME READY UP-TO-DATE AVAILABLE AGE hello-world 2/2 2 2 36s
The contents of cr-hello-world-app-service-epic-lb.yaml
are:
apiVersion: v1
kind: Service
metadata:
name: hello-world-service-epic-lb
labels:
hpecp.hpe.com/hpecp-internal-gateway: "true"
spec:
selector:
run: load-balancer-example
ports:
- name: http-hello
protocol: TCP
port: 8080
targetPort: 8080
type: NodePort
label
generates a service port on the Gateway host.
# kubectl create -f ./cr-hello-world-app-service-epic-lb.yaml service/hello-world-service-epic-lb created # kubectl describe services Name: hello-world-service-epic-lb Namespace: default Labels: hpecp.hpe.com/hpecp-internal-gateway: true Annotations: hpecp-internal-gateway/8080: mip.storage.enterprise.net:10003 - Note the Gateway host IP address. Selector: run=load-balancer-example Type: NodePort IP: 10.96.60.29 Port: http-hello 8080/TCP TargetPort: 8080/TCP NodePort: http 31996/TCP Endpoints: 10.244.1.5:8080,10.244.2.4:8080 Session Affinity: None External Traffic Policy: Cluster Events: <none> # curl http://mip.storage.enterprise.net:10003 Hello Kubernetes!
http://
in the cURL command above with
https://
.
If you cannot perform the mapping and receive Error 409 when executing the command
kubectl -n <namespace> logs
kubedirector-<port_number>
, be sure that HPE Ezmeral Runtime Enterprise is not in Lockdown mode. See Lockdown Mode.
Example 2: PHP Guestbook Application with Redis
The following example is based on the PHP Guestbook sample scenario described here (link opens an external web site in a new browser tab/window).
Begin by launching the Redis services.
# kubectl apply -f https://kubernetes.io/examples/application/guestbook/redis-master-deployment.yaml deployment.apps/redis-master created # kubectl get pods NAME READY STATUS RESTARTS AGE redis-master-7db7f6579f-s5llz 1/1 Running 0 79s # kubectl logs -f -c master redis-master-7db7f6579f-s5llz _._ _.-``__ ''-._ _.-`` `. `_. ''-._ Redis 2.8.19 (00000000/0) 64 bit .-`` .-```. ```\/ _.,_ ''-._ ( ' , .-` | `, ) Running in stand alone mode |`-._`-...-` __...-.``-._|'` _.-'| Port: 6379 | `-._ `._ / _.-' | PID: 1 `-._ `-._ `-./ _.-' _.-' |`-._`-._ `-.__.-' _.-'_.-'| | `-._`-._ _.-'_.-' | http://redis.io `-._ `-._`-.__.-'_.-' _.-' |`-._`-._ `-.__.-' _.-'_.-'| | `-._`-._ _.-'_.-' | `-._ `-._`-.__.-'_.-' _.-' `-._ `-.__.-' _.-' `-._ _.-' `-.__.-' [1] 28 Nov 03:08:51.748 # Server started, Redis version 2.8.19 [1] 28 Nov 03:08:51.749 # WARNING: The TCP backlog setting of 511 cannot be enforced because /proc/sys/net/core/somaxconn is set to the lower value of 128. [1] 28 Nov 03:08:51.749 * The server is now ready to accept connections on port 6379 <CTRL-C> # kubectl apply -f https://kubernetes.io/examples/application/guestbook/redis-master-service.yaml service/redis-master created # kubectl get service NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 5h21m redis-master ClusterIP 10.96.79.194 <none> 6379/TCP 41s # kubectl apply -f https://kubernetes.io/examples/application/guestbook/redis-slave-deployment.yaml deployment.apps/redis-slave created # kubectl get pods NAME READY STATUS RESTARTS AGE redis-master-545d695785-w2827 1/1 Running 0 12m redis-slave-546fc99d45-5ffm2 1/1 Running 0 29s redis-slave-546fc99d45-766rt 1/1 Running 0 29s # kubectl apply -f https://kubernetes.io/examples/application/guestbook/redis-slave-service.yaml service/redis-slave created # kubectl get services NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 5h26m redis-master ClusterIP 10.96.79.194 <none> 6379/TCP 5m16s redis-slave ClusterIP 10.96.55.128 <none> 6379/TCP 42s
Next, set up the Guestbook front-end service.
# kubectl apply -f https://kubernetes.io/examples/application/guestbook/frontend-deployment.yaml deployment.apps/frontend created # kubectl get pods NAME READY STATUS RESTARTS AGE frontend-678d98b8f7-754zv 0/1 ContainerCreating 0 40s frontend-678d98b8f7-g5jtf 0/1 ContainerCreating 0 40s frontend-678d98b8f7-l6xw9 0/1 ContainerCreating 0 40s redis-master-545d695785-w2827 1/1 Running 0 18m redis-slave-546fc99d45-5ffm2 1/1 Running 0 6m6s redis-slave-546fc99d45-766rt 1/1 Running 0 6m6s # kubectl get pods -l app=guestbook -l tier=frontend NAME READY STATUS RESTARTS AGE frontend-678d98b8f7-754zv 1/1 Running 0 2m47s frontend-678d98b8f7-g5jtf 1/1 Running 0 2m47s frontend-678d98b8f7-l6xw9 1/1 Running 0 2m47s # kubectl apply -f https://kubernetes.io/examples/application/guestbook/frontend-service.yaml service/frontend created # kubectl get services NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE frontend NodePort 10.96.165.194 <none> 80:31809/TCP 2m44s kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 5h36m redis-master ClusterIP 10.96.79.194 <none> 6379/TCP 15m redis-slave ClusterIP 10.96.55.128 <none> 6379/TCP 10m
Label the service so that the front-end NodePort service will be exposed via the Gateway host. This step is not necessary if the service was created in the namespace of a tenant that has the Map Services To Gateway option enabled. See Creating a New Kubernetes Tenant or Project and Editing an Existing Kubernetes Tenant or Project.
# kubectl label svc frontend hpecp.hpe.com/hpecp-internal-gateway=true service/frontend labeled # kubectl describe services frontend Name: frontend Namespace: default Labels: app=guestbook hpecp.hpe.com/hpecp-internal-gateway=true tier=frontend Annotations: hpecp-internal-gateway/80: mip.storage.enterprise.net:10004 - Note the URL. Selector: app=guestbook,tier=frontend Type: NodePort IP: 10.96.165.194 Port: <unset> 80/TCP TargetPort: 80/TCP NodePort: <unset> 31809/TCP Endpoints: 10.244.1.6:80,10.244.1.7:80,10.244.2.7:80 Session Affinity: None External Traffic Policy: Cluster Events: Type Reason Age From Message ---- ------ ---- ---- ------- Normal Service 38s kubedirector Created HPECP K8S service
Finally, the connection to the service using your browser. In this case, the port
does not have an "http-" name prefix and the Gateway host is not doing SSL
termination. You can therefore navigate to http://<url_described_above>
.
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Example 3: WordPress with Persistent Volume
The following example is based on the WordPress and MySQL with Persistent Volume described here (link opens an external web site in a new browser tab/window).
MySQL and WordPress each require a Persistent Volume to store data. Their Persistent Volume Claims will be created at the deployment step. HPE Ezmeral Data Fabric is used as the default persistent volume.
Begin by adding a Secret generator in kustomization.yaml
by
executing the following command, being sure to replace YOUR_PASSWORD
with the password you want to use.
# mkdir wordpress # cd wordpress # secretGenerator: - name: mysql-pass literals: - password=YOUR_PASSWORD EOF
Next, use either of the following methods to download the following two YAML manifest files for the MySQL and WordPress services, respectively (links open an external website in a new browser tab/window):
- https://kubernetes.io/examples/application/wordpress/mysql-deployment.yaml
- https://kubernetes.io/examples/application/wordpress/wordpress-deployment.yaml
# curl -kO https://kubernetes.io/examples/application/wordpress/mysql-deployment.yaml % Total % Received % Xferd Average Speed Time Time Time Current Dload Upload Total Spent Left Speed 100 1238 100 1238 0 0 1430 0 --:--:-- --:--:-- --:--:-- 1429 # curl -kO https://kubernetes.io/examples/application/wordpress/wordpress-deployment.yaml % Total % Received % Xferd Average Speed Time Time Time Current Dload Upload Total Spent Left Speed 100 1323 100 1323 0 0 1441 0 --:--:-- --:--:-- --:--:-- 1441 # ls -al total 9 drwxr-xr-x 1 leedavid UsersGrp 0 Nov 28 16:50 . drwx------ 1 leedavid UsersGrp 0 Nov 28 16:46 .. -rw-r--r-- 1 leedavid UsersGrp 137 Nov 28 16:49 kustomization.yaml -rw-r--r-- 1 leedavid UsersGrp 1238 Nov 28 16:47 mysql-deployment.yaml -rw-r--r-- 1 leedavid UsersGrp 1323 Nov 28 16:50 wordpress-deployment.yaml
If you installed HPE Ezmeral Runtime Enterprise with tenant storage, then HPE Ezmeral Data Fabric will already be registered as the default Storage Class in this namespace.
# kubectl get StorageClass NAME PROVISIONER AGE default (default) com.mapr.csi-kdf 39h # kubectl describe StorageClass Name: default IsDefaultClass: Yes Annotations: storageclass.kubernetes.io/is-default-class=true Provisioner: com.mapr.csi-kdf Parameters: cldbHosts=192.168.20.131:7222,cluster=epic.mapr.cluster,csi.storage.k8s.io/provisioner-secret-name=mapr-user-secret,csi.storage.k8s.io/provisioner-secret-namespace=mapr-csi,csiNodePublishSecretName=mapr-ticket-secret,csiNodePublishSecretNamespace=mapr-csi,mountPrefix=/mapr-csi,namePrefix=k8s-1-,platinum=true,restServers=192.168.20.131:8443,securityType=secure AllowVolumeExpansion: <unset> MountOptions: <none> ReclaimPolicy: Delete VolumeBindingMode: Immediate Events: <none>
In these two manifest files, both the WordPress service and MySQL are requesting a persistent volume (PV):
-
MySQL Deployment:
-
WordPress Deployment:
Neither pod makes any explicit request for a specific storageClassName. Hence, they will use the default HPE Ezmeral Data Fabric StorageClass.
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NodePort Service
Edit the WordPress manifest YAML to use the NodePort service instead of LoadBalancer service. This needs to be done for port mapping to occur.
# vi wordpress-deployment.yaml # cat wordpress-deployment.yaml apiVersion: v1 kind: Service metadata: name: wordpress labels: app: wordpress spec: ports: - port: 80 selector: app: wordpress tier: frontend type: NodePort - Ensure this is set to NodePort. --- apiVersion: v1 kind: PersistentVolumeClaim metadata: name: wp-pv-claim labels: app: wordpress spec: accessModes: - ReadWriteOnce resources: requests: storage: 20Gi --- apiVersion: apps/v1 # for versions before 1.9.0 use apps/v1beta2 kind: Deployment metadata: name: wordpress labels: app: wordpress spec: selector: matchLabels: app: wordpress tier: frontend strategy: type: Recreate template: metadata: labels: app: wordpress tier: frontend spec: containers: - image: wordpress:4.8-apache name: wordpress env: - name: WORDPRESS_DB_HOST value: wordpress-mysql - name: WORDPRESS_DB_PASSWORD valueFrom: secretKeyRef: name: mysql-pass key: password ports: - containerPort: 80 name: wordpress volumeMounts: - name: wordpress-persistent-storage mountPath: /var/www/html volumes: - name: wordpress-persistent-storage persistentVolumeClaim: claimName: wp-pv-claim
Continue by adding these two manifests to the kustomization.yaml
file.
# cat <<EOF >>./kustomization.yaml resources: - mysql-deployment.yaml - wordpress-deployment.yaml EOF
The kustomization.yaml
contains all of the resources for deploying a
WordPress site and a MySQL database. You can apply the directory, and then verify
both the HPE Ezmeral Data Fabric volumes and the services, as
follows:
# kubectl apply --kustomize ./ secret/mysql-pass-9tt65k5fgm created service/wordpress-mysql created service/wordpress created deployment.apps/wordpress-mysql created deployment.apps/wordpress created persistentvolumeclaim/mysql-pv-claim created persistentvolumeclaim/wp-pv-claim created
Confirm that PVC is using the HPE Ezmeral Data Fabric StorageClass (see highlighted text below).
# kubectl get pvc NAME STATUS VOLUME CAPACITY ACCESS MODES STORAGECLASS AGE mysql-pv-claim Bound mapr-pv-16f97a33-b8dd-488a-b6db-1d94a84286e2 20Gi RWO default 48s wp-pv-claim Bound mapr-pv-896b3504-e9ba-4593-b9a0-88a9ece392b5 20Gi RWO default 48s # kubectl get pv NAME CAPACITY ACCESS MODES RECLAIM POLICY STATUS CLAIM STORAGECLASS REASON AGE mapr-pv-32850109-ef66-42db-9522-b563fbc01eae 10Gi RWO Delete Bound bdwebterm/pvc-kd-977sb-0 default 41h mapr-pv-a24b1733-39db-40d2-bdaf-0be7c22ed83b 10Gi RWO Delete Bound bdwebterm/pvc-kd-nbwhn-0 default 31h mapr-pv-dbf96aed-dafd-47b7-87d4-7d343f182d8b 20Gi RWO Delete Bound default/mysql-pv-claim default 69s mapr-pv-e3c1db71-2865-425c-971e-c01466e9d295 20Gi RWO Delete Bound default/wp-pv-claim default 69s mapr-pv-ed5f1be3-9be2-4470-83cf-67f9b31e9dbf 10Gi RWO Delete Bound bdwebterm/pvc-kd-dl26j-0 default 32h
Label the WordPress service so that the front-end NodePort service will be exposed via the Gateway host. This step is not necessary if the service was created in the namespace of a tenant that has the Map Services To Gateway option enabled. See Creating a New Kubernetes Tenant or Project and Editing an Existing Kubernetes Tenant or Project.
# kubectl get services NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 26h wordpress NodePort 10.96.98.248 <none> 80:30996/TCP 24s wordpress-mysql ClusterIP None <none> 3306/TCP 24s # kubectl label svc wordpress hpecp.hpe.com/hpecp-internal-gateway=true service/wordpress labeled # kubectl describe service wordpress Name: wordpress Namespace: default Labels: app=wordpress hpecp.hpe.com/hpecp-internal-gateway=true Annotations: hpecp-internal-gateway/80: mip.storage.enterprise.net:10006 Selector: app=wordpress,tier=frontend Type: NodePort IP: 10.96.98.248 Port: <unset> 80/TCP TargetPort: 80/TCP NodePort: <unset> 30996/TCP Endpoints: 10.244.2.11:80 Session Affinity: None External Traffic Policy: Cluster Events: Type Reason Age From Message ---- ------ ---- ---- ------- Normal Service 26s kubedirector Created HPECP K8S service
Copy the IP address and port number (see highlighted text above) to your browser. You should see set-up page similar to the following screenshot:
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Destroy the application deployments (e.g. pods) and restart the deployments, making sure to preserve the WordPress application information and still preserved.
# kubectl delete deployment wordpress deployment.extensions "wordpress" deleted # kubectl delete deployment wordpress-mysql deployment.extensions "wordpress-mysql" deleted # kubectl get pods No resources found. # kubectl get deployments No resources found.
The service is gone, as expected.
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Reapply the same deployment, and reconnect to persistent storage.
# kubectl apply -k ./ secret/mysql-pass-9tt65k5fgm unchanged service/wordpress-mysql unchanged service/wordpress unchanged deployment.apps/wordpress-mysql created deployment.apps/wordpress created persistentvolumeclaim/mysql-pv-claim unchanged persistentvolumeclaim/wp-pv-claim unchanged # kubectl get pods NAME READY STATUS RESTARTS AGE wordpress-594759d7f6-jdnvp 1/1 Running 0 27s wordpress-mysql-847b7b996d-dwf6s 1/1 Running 0 28s # kubectl describe service wordpress Name: wordpress Namespace: default Labels: app=wordpress Hpecp.hpe.com/hpecp-internal-gateway=true Annotations: hpecp-internal-gateway/80: mip.storage.enterprise.net:10006 Selector: app=wordpress,tier=frontend Type: NodePort IP: 10.96.35.129 Port: <unset> 80/TCP TargetPort: 80/TCP NodePort: <unset> 31589/TCP Endpoints: 10.244.1.18:80 Session Affinity: None External Traffic Policy: Cluster Events: Type Reason Age From Message ---- ------ ---- ---- ------- Normal Service 12m kubedirector Created HPECP K8S service
The WordPress service is restored.
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Finally, you will need to delete the entire deployment in order to free up all of the resources, including the persistent storage.
# kubectl delete -k ./ secret "mysql-pass-9tt65k5fgm" deleted service "wordpress-mysql" deleted service "wordpress" deleted deployment.apps "wordpress-mysql" deleted deployment.apps "wordpress" deleted persistentvolumeclaim "mysql-pv-claim" deleted persistentvolumeclaim "wp-pv-claim" deleted