Digitalis Cassandra Chart

Digitalis Cassandra and AxonOps

This chart was forked and adapted from incubator to run Cassandra together with AxonOps.

Enable the chart repo with

helm repo add axonops-helm https://repo.axonops.com/public/helm/helm/charts/

Install Chart

To install the Cassandra Chart into your Kubernetes cluster (This Chart requires persistent volume by default, you may need to create a storage class before install chart. To create storage class, see Persist data section)

helm install --namespace "cassandra" -n "cassandra" axonops-helm/cassandra

After installation succeeds, you can get a status of Chart

helm status "cassandra"

If you want to delete your Chart, use this command

helm delete  --purge "cassandra"

Upgrading

To upgrade your Cassandra release, simply run

helm upgrade "cassandra" axonops-helm/cassandra

Persist data

You need to create StorageClass before able to persist data in persistent volume. To create a StorageClass on Google Cloud, run the following

kubectl create -f sample/create-storage-gce.yaml

And set the following values in values.yaml

persistence:
  enabled: true

If you want to create a StorageClass on other platform, please see documentation here https://kubernetes.io/docs/user-guide/persistent-volumes/

When running a cluster without persistence, the termination of a pod will first initiate a decommissioning of that pod. Depending on the amount of data stored inside the cluster this may take a while. In order to complete a graceful termination, pods need to get more time for it. Set the following values in values.yaml:

podSettings:
  terminationGracePeriodSeconds: 1800

Install Chart with specific cluster size

By default, this Chart will create a cassandra with 3 nodes. If you want to change the cluster size during installation, you can use --set config.cluster_size={value} argument. Or edit values.yaml

For example: Set cluster size to 5

helm install --namespace "cassandra" -n "cassandra" --set config.cluster_size=5 incubator/cassandra/

Install Chart with specific resource size

By default, this Chart will create a cassandra with CPU 2 vCPU and 4Gi of memory which is suitable for development environment. If you want to use this Chart for production, I would recommend to update the CPU to 4 vCPU and 16Gi. Also increase size of max_heap_size and heap_new_size. To update the settings, edit values.yaml

Install Chart with specific node

Sometime you may need to deploy your cassandra to specific nodes to allocate resources. You can use node selector by edit nodes.enabled=true in values.yaml For example, you have 6 vms in node pools and you want to deploy cassandra to node which labeled as cloud.google.com/gke-nodepool: pool-db

Set the following values in values.yaml

nodes:
  enabled: true
  selector:
    nodeSelector:
      cloud.google.com/gke-nodepool: pool-db

Configuration

The following table lists the configurable parameters of the Cassandra chart and their default values.

Parameter	Description	Default
image.repo	cassandra image repository	digitalisdocker/cassandra
image.tag	cassandra image tag	3.11.9
image.pullPolicy	Image pull policy	Always if imageTag is latest, else IfNotPresent
image.pullSecrets	Image pull secrets	nil
config.cluster_domain	The name of the cluster domain.	cluster.local
config.cluster_name	The name of the cluster.	cassandra
config.cluster_size	The number of nodes in the cluster.	3
config.seed_size	The number of seed nodes used to bootstrap new clients joining the cluster.	2
config.seeds	The comma-separated list of seed nodes.	Automatically generated according to .Release.Name and config.seed_size
config.num_tokens	Initdb Arguments	256
config.dc_name	Initdb Arguments	DC1
config.rack_name	Initdb Arguments	RAC1
config.endpoint_snitch	Initdb Arguments	SimpleSnitch
config.max_heap_size	Initdb Arguments	2048M
config.heap_new_size	Initdb Arguments	512M
config.ports.cql	Initdb Arguments	9042
config.ports.thrift	Initdb Arguments	9160
config.ports.agent	The port of the JVM Agent (if any)	nil
config.start_rpc	Initdb Arguments	false
configOverrides	Overrides config files in /etc/cassandra dir	{}
commandOverrides	Overrides default docker command	[]
argsOverrides	Overrides default docker args	[]
env	Custom env variables	{}
schedulerName	Name of k8s scheduler (other than the default)	nil
persistence.enabled	Use a PVC to persist data	true
persistence.storageClass	Storage class of backing PVC	nil (uses alpha storage class annotation)
persistence.accessMode	Use volume as ReadOnly or ReadWrite	ReadWriteOnce
persistence.size	Size of data volume	10Gi
resources	CPU/Memory resource requests/limits	Memory: 4Gi, CPU: 2
service.type	k8s service type exposing ports, e.g. NodePort	ClusterIP
service.annotations	Annotations to apply to cassandra service	""
podManagementPolicy	podManagementPolicy of the StatefulSet	OrderedReady
podDisruptionBudget	Pod distruption budget	{}
podAnnotations	pod annotations for the StatefulSet	{}
updateStrategy.type	UpdateStrategy of the StatefulSet	OnDelete
livenessProbe.initialDelaySeconds	Delay before liveness probe is initiated	90
livenessProbe.periodSeconds	How often to perform the probe	30
livenessProbe.timeoutSeconds	When the probe times out	5
livenessProbe.successThreshold	Minimum consecutive successes for the probe to be considered successful after having failed.	1
livenessProbe.failureThreshold	Minimum consecutive failures for the probe to be considered failed after having succeeded.	3
readinessProbe.initialDelaySeconds	Delay before readiness probe is initiated	90
readinessProbe.periodSeconds	How often to perform the probe	30
readinessProbe.timeoutSeconds	When the probe times out	5
readinessProbe.successThreshold	Minimum consecutive successes for the probe to be considered successful after having failed.	1
readinessProbe.failureThreshold	Minimum consecutive failures for the probe to be considered failed after having succeeded.	3
readinessProbe.address	Address to use for checking node has joined the cluster and is ready.	${POD_IP}
rbac.create	Specifies whether RBAC resources should be created	true
serviceAccount.create	Specifies whether a ServiceAccount should be created	true
serviceAccount.name	The name of the ServiceAccount to use
serviceAccount.rules	Permissions you would like granting to the pods	{}
backup.enabled	Enable backup on chart installation	false
backup.schedule	Keyspaces to backup, each with cron time
backup.annotations	Backup pod annotations	iam.amazonaws.com/role: cain
backup.image.repository	Backup image repository	maorfr/cain
backup.image.tag	Backup image tag	0.6.0
backup.extraArgs	Additional arguments for cain	[]
backup.env	Backup environment variables	AWS_REGION: us-east-1
backup.resources	Backup CPU/Memory resource requests/limits	Memory: 1Gi, CPU: 1
backup.destination	Destination to store backup artifacts	s3://bucket/cassandra
backup.google.serviceAccountSecret	Secret containing credentials if GCS is used as destination
exporter.enabled	Enable Cassandra exporter	false
exporter.servicemonitor.enabled	Enable ServiceMonitor for exporter	true
exporter.servicemonitor.additionalLabels	Additional labels for Service Monitor	{}
exporter.image.repo	Exporter image repository	criteord/cassandra_exporter
exporter.image.tag	Exporter image tag	2.0.2
exporter.port	Exporter port	5556
exporter.jvmOpts	Exporter additional JVM options
exporter.resources	Exporter CPU/Memory resource requests/limits	{}
extraContainers	Sidecar containers for the pods	[]
extraVolumes	Additional volumes for the pods	[]
extraVolumeMounts	Extra volume mounts for the pods	[]
extraInitContainers	Sidecar containers to init the pods	[]
extraInitVolumes	Additional volumes for init containers	[]
extraInitVolumeMounts	Extra volume mounts for init containers	[]
affinity	Kubernetes node affinity	{}
tolerations	Kubernetes node tolerations	[]

Scale cassandra

When you want to change the cluster size of your cassandra, you can use the helm upgrade command.

helm upgrade --set config.cluster_size=5 cassandra incubator/cassandra

Get cassandra status

You can get your cassandra cluster status by running the command

kubectl exec -it --namespace cassandra $(kubectl get pods --namespace cassandra -l app=cassandra-cassandra -o jsonpath='{.items[0].metadata.name}') nodetool status

Output

Datacenter: asia-east1
======================
Status=Up/Down
|/ State=Normal/Leaving/Joining/Moving
--  Address    Load       Tokens       Owns (effective)  Host ID                               Rack
UN  10.8.1.11  108.45 KiB  256          66.1%             410cc9da-8993-4dc2-9026-1dd381874c54  a
UN  10.8.4.12  84.08 KiB  256          68.7%             96e159e1-ef94-406e-a0be-e58fbd32a830  c
UN  10.8.3.6   103.07 KiB  256          65.2%             1a42b953-8728-4139-b070-b855b8fff326  b

Benchmark

You can use cassandra-stress tool to run the benchmark on the cluster by the following command

kubectl exec -it --namespace cassandra $(kubectl get pods --namespace cassandra -l app=cassandra-cassandra -o jsonpath='{.items[0].metadata.name}') cassandra-stress

Example of cassandra-stress argument

• Run both read and write with ration 9:1
• Operator total 1 million keys with uniform distribution
• Use QUORUM for read/write
• Generate 50 threads
• Generate result in graph
• Use NetworkTopologyStrategy with replica factor 2

cassandra-stress mixed ratio\(write=1,read=9\) n=1000000 cl=QUORUM -pop dist=UNIFORM\(1..1000000\) -mode native cql3 -rate threads=50 -log file=~/mixed_autorate_r9w1_1M.log -graph file=test2.html title=test revision=test2 -schema "replication(strategy=NetworkTopologyStrategy, factor=2)"