CDK on OpenStack
The Charmed Distribution of Kubernetes® will run seamlessly
on OpenStack. With the addition of the
openstack-integrator, your cluster
will also be able to directly use OpenStack native features.
openstack-integrator charm simplifies working with CDK on OpenStack. Using the
credentials provided to Juju, it acts as a proxy between CDK and the underlying cloud,
granting permissions to dynamically create, for example, Cinder volumes.
When installing CDK using the Juju bundle, you can add the openstack-integrator at the same time by using the following overlay file (download it here):
applications: openstack-integrator: charm: cs:~containers/openstack-integrator num_units: 1 relations: - ['openstack-integrator', 'kubernetes-master'] - ['openstack-integrator', 'kubernetes-worker']
To use this overlay with the CDK bundle, it is specified during deploy like this:
juju deploy charmed-kubernetes --overlay ~/path/openstack-overlay.yaml
Then run the command to share credentials with this charm:
juju trust openstack-integrator
... and remember to fetch the configuration file!
juju scp kubernetes-master/0:config ~/.kube/config
For more configuration options and details of the permissions which the integrator uses, please see the charm readme.
Using Cinder volumes
Many pods you may wish to deploy will require storage. Although you can use any type of storage supported by Kubernetes (see the storage documentation), you also have the option to use Cinder storage volumes, if supported by your OpenStack.
cinder storage class will be automatically created for you when the integrator is
used. This storage class can then be used when creating a Persistent Volume Claim:
kubectl create -f - <<EOY kind: PersistentVolumeClaim apiVersion: v1 metadata: name: testclaim spec: accessModes: - ReadWriteOnce resources: requests: storage: 100Mi storageClassName: cinder EOY
This should finish with a confirmation. You can check the current PVCs with:
kubectl get pvc
...which should return something similar to:
NAME STATUS VOLUME CAPACITY ACCESS MODES STORAGECLASS AGE testclaim Bound pvc-54a94dfa-3128-11e9-9c54-028fdae42a8c 1Gi RWO cinder 9s
This PVC can then be used by pods operating in the cluster. As an example, the following
kubectl create -f - <<EOY apiVersion: v1 kind: Pod metadata: name: busybox namespace: default spec: containers: - image: busybox command: - sleep - "3600" imagePullPolicy: IfNotPresent name: busybox volumeMounts: - mountPath: "/pv" name: testvolume restartPolicy: Always volumes: - name: testvolume persistentVolumeClaim: claimName: testclaim EOY
Note: If you create Cinder volumes and subsequently tear down the cluster, check with the OpenStack administration tools to make sure all the associated resources have also been released.
Using LBaaS load balancers
With the openstack-integrator charm in place, actions which invoke a loadbalancer in Kubernetes will automatically request a load balancer from OpenStack using Octavia, if available, or Neutron. This can be demonstrated with a simple application. Here we will create a simple application running in five pods:
kubectl run hello-world --replicas=5 --labels="run=load-balancer-example" --image=gcr.io/google-samples/node-hello:1.0 --port=8080
You can verify that the application and replicas have been created with:
kubectl get deployments hello-world
Which should return output similar to:
NAME READY UP-TO-DATE AVAILABLE AGE hello-world 5/5 5 5 2m38s
To create a LoadBalancer, the application should now be exposed as a service:
kubectl expose deployment hello-world --type=LoadBalancer --name=hello
To check that the service is running correctly:
kubectl get service hello
...which should return output similar to:
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE hello LoadBalancer 10.152.183.136 22.214.171.124 8080:32662/TCP 2m
You can see that the External IP is now in front of the five endpoints of the example deployment. You can test the ingress address:
Note: If you create load balancers and subsequently tear down the cluster, check with the OpenStack administration tools to make sure all the associated resources have also been released.
Upgrading the integrator charm
The openstack-integrator is not specifically tied to the version of CDK installed and may generally be upgraded at any time with the following command:
juju upgrade-charm openstack-integrator
If you have any specific problems with the openstack-integrator, you can report bugs on Launchpad.
For logs of what the charm itself believes the world to look like, you can use Juju to replay the log history for that specific unit:
juju debug-log --replay --include openstack-integrator/0