# Cassandra A Cassandra Chart for Kubernetes ## 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](#persist_data) section) ```bash helm install --namespace "cassandra" -n "cassandra" incubator/cassandra ``` After installation succeeds, you can get a status of Chart ```bash helm status "cassandra" ``` If you want to delete your Chart, use this command ```bash helm delete --purge "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 ```bash kubectl create -f sample/create-storage-gce.yaml ``` And set the following values in `values.yaml` ```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/](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`: ```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 ```bash 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` ```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 | `cassandra` | | `image.tag` | `cassandra` image tag | `3.11.3` | | `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 | `{}` | | `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` | | `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` | | `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 | | | `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.repo` | Backup image repository | `nuvo/cain` | | `backup.image.tag` | Backup image tag | `0.4.1` | | `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` | | `exporter.enabled` | Enable Cassandra exporter | `false` | | `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 | | | `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. ```bash helm upgrade --set config.cluster_size=5 cassandra incubator/cassandra ``` ## Get cassandra status You can get your cassandra cluster status by running the command ```bash kubectl exec -it --namespace cassandra $(kubectl get pods --namespace cassandra -l app=cassandra-cassandra -o jsonpath='{.items[0].metadata.name}') nodetool status ``` Output ```bash 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](https://docs.datastax.com/en/cassandra/3.0/cassandra/tools/toolsCStress.html) tool to run the benchmark on the cluster by the following command ```bash 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 ```bash 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)" ```