Troubleshooting and Limitations in Kubernetes Environments

Find advice for troubleshooting issues you might face while deploying Hazelcast via Helm.

Limitations

Hazelcast CP Subsystem can be used safely in Kubernetes only if CP Subsystem Persistence is enabled (Enterprise Feature). Otherwise, a CP Subsystem Group may not recover after scaling the cluster or a rolling upgrade.

Troubleshooting with Helm Installation

Why is Management Center EXTERNAL-IP not assigned?

Minikube is a tool that makes it easy to run Kubernetes locally. However, It does not come with LoadBalancer so Management Center can’t be accessible with external IP.

You can see below that EXTERNAL-IP is pending when you install hazelcast helm charts via helm install

kubectl get services
NAME                                                   TYPE           CLUSTER-IP      EXTERNAL-IP   PORT(S)          AGE
service/kubernetes                                     ClusterIP      10.96.0.1       <none>        443/TCP          3h
service/littering-pig-hazelcast-enterprise             ClusterIP      10.98.41.236    <none>        5701/TCP         3h
service/littering-pig-hazelcast-enterprise-mancenter   LoadBalancer   10.104.97.143   <pending>     8080:30145/TCP   3h

However, you can still reach Hazelcast Management Center with the http://MINIKUBE_IP:30145 for the case above. $(minikube ip) is the command to retrieve minikube IP address.

"cluster-admin" not found

In some Kubernetes Clusters, RBAC might not be enabled by default so you might end up seeing RBAC related error while helm install.

Error: release funky-woodpecker failed: roles.rbac.authorization.k8s.io “funky-woodpecker-hazelcast-enterprise” is forbidden: attempt to grant extra privileges: [PolicyRule{APIGroups:[“”], Resources:[“endpoints”], Verbs:[“get”]} PolicyRule{APIGroups:[“”], Resources:[“endpoints”], Verbs:[“list”]}] user=&{system:serviceaccount:kube-system:tiller 411da847-9999-11e8-bf5e-ba0dc6d88758 [system:serviceaccounts system:serviceaccounts:kube-system system:authenticated] map[]} ownerrules=[] ruleResolutionErrors=[clusterroles.rbac.authorization.k8s.io “cluster-admin” not found]

In that case, you need either enable debug or pass --set rbac.create=false into your helm install command.

Why is Management Center Pod in Pending state?

NAME                                                            READY     STATUS              RESTARTS   AGE
dining-serval-hazelcast-enterprise-0                            1/1       Running             0          50s
dining-serval-hazelcast-enterprise-1                            0/1       Running             0          19s
dining-serval-hazelcast-enterprise-mancenter-5f56d785dc-h5slc   0/1       Pending             0          50s

If you see your Management Center in a Pending State as above, you can try a few things for troubleshooting.

Firstly, you can check if Persistent Volume and PersistentVolumeClaim are already bound.

kubectl get pv
NAME                                       CAPACITY   ACCESS MODES   RECLAIM POLICY   STATUS    CLAIM                                                  STORAGECLASS   REASON    AGE
pvc-7f4baaff-a63d-11e8-9df7-0800277c0239   8Gi        RWO            Delete           Bound     default/mouthy-alpaca-hazelcast-enterprise-mancenter   standard                 4d

kubectl get pvc
NAME                                           STATUS    VOLUME                                     CAPACITY   ACCESS MODES   STORAGECLASS   AGE
mouthy-alpaca-hazelcast-enterprise-mancenter   Bound     pvc-7f4baaff-a63d-11e8-9df7-0800277c0239   8Gi        RWO            standard       4d

You can see they are bound as above. If they are not, this is the list of potential problems you might be having.

Creating Storage Class

Some Kubernetes Providers do not offer default storage class so you have to create one and pass it to helm installation.

Create storage.yaml file and apply via kubectl apply -f storage.yaml
```
kind: StorageClass
apiVersion: storage.k8s.io/v1
metadata:
  name: standard
provisioner: kubernetes.io/aws-ebs
parameters:
  type: gp2
  zones: us-west-2a, us-west-2b, us-west-2c
```
Use storage class name defined in the storage.yaml file in helm installation.
```
helm install my-release --set mancenter.persistence.storageClass=standard hazelcast/<chart>
```

Persistent Volume Availability Zone

AWS EKS requires your volume to be in the same Availability Zone as Kubernetes Nodes that Management Center Pod is running. Otherwise, Management Center Pod will be stuck in pending state. You can check failure-domain.beta.kubernetes.io/zone labels on the Kubernetes Nodes and Persistent Volume and see PersistentVolume is in one of the node’s Availability Zone.

kubectl get no --show-labels
NAME                                            STATUS    ROLES     AGE       VERSION   LABELS
ip-192-168-101-236.us-west-2.compute.internal   Ready     <none>    42m       v1.10.3   beta.kubernetes.io/arch=amd64,beta.kubernetes.io/instance-type=t2.medium,beta.kubernetes.io/os=linux,failure-domain.beta.kubernetes.io/region=us-west-2,failure-domain.beta.kubernetes.io/zone=us-west-2a,kubernetes.io/hostname=ip-192-168-101-236.us-west-2.compute.internal
ip-192-168-245-179.us-west-2.compute.internal   Ready     <none>    42m       v1.10.3   beta.kubernetes.io/arch=amd64,beta.kubernetes.io/instance-type=t2.medium,beta.kubernetes.io/os=linux,failure-domain.beta.kubernetes.io/region=us-west-2,failure-domain.beta.kubernetes.io/zone=us-west-2c,kubernetes.io/hostname=ip-192-168-245-179.us-west-2.compute.internal

kubectl get pv --show-labels
NAME                                       CAPACITY   ACCESS MODES   RECLAIM POLICY   STATUS    CLAIM                                                  STORAGECLASS   REASON    AGE       LABELS
pvc-539749c4-9f31-11e8-b9d0-0af5b0ce3266   8Gi        RWO            Delete           Bound     default/dining-serval-hazelcast-enterprise-mancenter   standard                 30s       failure-domain.beta.kubernetes.io/region=us-west-2,failure-domain.beta.kubernetes.io/zone=us-west-2c

You need to reinstall hazelcast helm chart until you have both PersistentVolume and Kubernetes Node in the same Availability Zone.

Persistent Volume Creation Time

Creating Persistent Volume in some Kubernetes Environments take up to 5 minutes so you can wait for sometime to see if Persistent Volume is created.
```
kubectl get pv --watch
```
If you see Persistent Volume created, your Management Center Pod will be turning Running state soon.
Persistence Volume Claim Clean Up

Deleting the helm release of Hazelcast chart will not automatically delete the PVCs. To see the the PVCs run:
```
kubectl get pvc
```
To delete them run:
```
kubectl delete pvc <name-of-the-pvc>
```

"65534: must be in the ranges: [x, y]" or "65534 is not an allowed group"

In OpenShift (and IBM Cloud) environments, the projects/namespaces may be limited to the certain range of user and group ids. Then, installing Hazelcast helm charts with default values results in the following error:

forbidden: unable to validate against any security context constraint: [fsGroup: Invalid value: []int64{65534}: 65534 is not an allowed group spec.containers[0].securityContext.securityContext.runAsUser: Invalid value: 65534: must be in the ranges: [1000560000, 1000569999]]

When you face such an issue, you must pick the user and group ids between the allowed range and pass them to the helm chart as below:

helm install my-release --set securityContext.runAsUser=1000560000,securityContext.runAsGroup=1000560000,securityContext.fsGroup=1000560000 hazelcast/<chart>

Jet engine is disabled via external ConfigMap but it did not work

In that case, you also need to turn off JET engine via chart parameter(jet.enabled):

helm install my-release ... --set jet.enabled=false hazelcast/<chart>