216 lines
16 KiB
Markdown
216 lines
16 KiB
Markdown
# Cassandra
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A Cassandra Chart for Kubernetes
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## Install Chart
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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)
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```bash
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helm install --namespace "cassandra" -n "cassandra" incubator/cassandra
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```
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After installation succeeds, you can get a status of Chart
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```bash
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helm status "cassandra"
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```
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If you want to delete your Chart, use this command
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```bash
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helm delete --purge "cassandra"
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```
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## Upgrading
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To upgrade your Cassandra release, simply run
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```bash
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helm upgrade "cassandra" incubator/cassandra
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```
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### 0.12.0
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This version fixes https://github.com/helm/charts/issues/7803 by removing mutable labels in `spec.VolumeClaimTemplate.metadata.labels` so that it is upgradable.
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Until this version, in order to upgrade, you have to delete the Cassandra StatefulSet before upgrading:
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```bash
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$ kubectl delete statefulset --cascade=false my-cassandra-release
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```
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## Persist data
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You need to create `StorageClass` before able to persist data in persistent volume.
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To create a `StorageClass` on Google Cloud, run the following
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```bash
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kubectl create -f sample/create-storage-gce.yaml
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```
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And set the following values in `values.yaml`
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```yaml
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persistence:
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enabled: true
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```
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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/)
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When running a cluster without persistence, the termination of a pod will first initiate a decommissioning of that pod.
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Depending on the amount of data stored inside the cluster this may take a while. In order to complete a graceful
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termination, pods need to get more time for it. Set the following values in `values.yaml`:
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```yaml
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podSettings:
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terminationGracePeriodSeconds: 1800
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```
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## Install Chart with specific cluster size
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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`
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For example:
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Set cluster size to 5
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```bash
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helm install --namespace "cassandra" -n "cassandra" --set config.cluster_size=5 incubator/cassandra/
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```
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## Install Chart with specific resource size
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By default, this Chart will create a cassandra with CPU 2 vCPU and 4Gi of memory which is suitable for development environment.
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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`.
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To update the settings, edit `values.yaml`
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## Install Chart with specific node
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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`
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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`
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Set the following values in `values.yaml`
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```yaml
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nodes:
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enabled: true
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selector:
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nodeSelector:
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cloud.google.com/gke-nodepool: pool-db
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```
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## Configuration
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The following table lists the configurable parameters of the Cassandra chart and their default values.
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| Parameter | Description | Default |
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| ----------------------- | --------------------------------------------- | ---------------------------------------------------------- |
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| `image.repo` | `cassandra` image repository | `cassandra` |
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| `image.tag` | `cassandra` image tag | `3.11.5` |
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| `image.pullPolicy` | Image pull policy | `Always` if `imageTag` is `latest`, else `IfNotPresent` |
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| `image.pullSecrets` | Image pull secrets | `nil` |
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| `config.cluster_domain` | The name of the cluster domain. | `cluster.local` |
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| `config.cluster_name` | The name of the cluster. | `cassandra` |
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| `config.cluster_size` | The number of nodes in the cluster. | `3` |
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| `config.seed_size` | The number of seed nodes used to bootstrap new clients joining the cluster. | `2` |
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| `config.seeds` | The comma-separated list of seed nodes. | Automatically generated according to `.Release.Name` and `config.seed_size` |
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| `config.num_tokens` | Initdb Arguments | `256` |
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| `config.dc_name` | Initdb Arguments | `DC1` |
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| `config.rack_name` | Initdb Arguments | `RAC1` |
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| `config.endpoint_snitch` | Initdb Arguments | `SimpleSnitch` |
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| `config.max_heap_size` | Initdb Arguments | `2048M` |
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| `config.heap_new_size` | Initdb Arguments | `512M` |
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| `config.ports.cql` | Initdb Arguments | `9042` |
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| `config.ports.thrift` | Initdb Arguments | `9160` |
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| `config.ports.agent` | The port of the JVM Agent (if any) | `nil` |
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| `config.start_rpc` | Initdb Arguments | `false` |
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| `configOverrides` | Overrides config files in /etc/cassandra dir | `{}` |
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| `commandOverrides` | Overrides default docker command | `[]` |
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| `argsOverrides` | Overrides default docker args | `[]` |
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| `env` | Custom env variables | `{}` |
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| `schedulerName` | Name of k8s scheduler (other than the default) | `nil` |
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| `persistence.enabled` | Use a PVC to persist data | `true` |
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| `persistence.storageClass` | Storage class of backing PVC | `nil` (uses alpha storage class annotation) |
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| `persistence.accessMode` | Use volume as ReadOnly or ReadWrite | `ReadWriteOnce` |
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| `persistence.size` | Size of data volume | `10Gi` |
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| `resources` | CPU/Memory resource requests/limits | Memory: `4Gi`, CPU: `2` |
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| `service.type` | k8s service type exposing ports, e.g. `NodePort`| `ClusterIP` |
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| `service.annotations` | Annotations to apply to cassandra service | `""` |
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| `podManagementPolicy` | podManagementPolicy of the StatefulSet | `OrderedReady` |
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| `podDisruptionBudget` | Pod distruption budget | `{}` |
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| `podAnnotations` | pod annotations for the StatefulSet | `{}` |
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| `updateStrategy.type` | UpdateStrategy of the StatefulSet | `OnDelete` |
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| `livenessProbe.initialDelaySeconds` | Delay before liveness probe is initiated | `90` |
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| `livenessProbe.periodSeconds` | How often to perform the probe | `30` |
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| `livenessProbe.timeoutSeconds` | When the probe times out | `5` |
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| `livenessProbe.successThreshold` | Minimum consecutive successes for the probe to be considered successful after having failed. | `1` |
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| `livenessProbe.failureThreshold` | Minimum consecutive failures for the probe to be considered failed after having succeeded. | `3` |
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| `readinessProbe.initialDelaySeconds` | Delay before readiness probe is initiated | `90` |
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| `readinessProbe.periodSeconds` | How often to perform the probe | `30` |
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| `readinessProbe.timeoutSeconds` | When the probe times out | `5` |
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| `readinessProbe.successThreshold` | Minimum consecutive successes for the probe to be considered successful after having failed. | `1` |
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| `readinessProbe.failureThreshold` | Minimum consecutive failures for the probe to be considered failed after having succeeded. | `3` |
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| `readinessProbe.address` | Address to use for checking node has joined the cluster and is ready. | `${POD_IP}` |
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| `rbac.create` | Specifies whether RBAC resources should be created | `true` |
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| `serviceAccount.create` | Specifies whether a ServiceAccount should be created | `true` |
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| `serviceAccount.name` | The name of the ServiceAccount to use | |
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| `backup.enabled` | Enable backup on chart installation | `false` |
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| `backup.schedule` | Keyspaces to backup, each with cron time | |
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| `backup.annotations` | Backup pod annotations | iam.amazonaws.com/role: `cain` |
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| `backup.image.repository` | Backup image repository | `maorfr/cain` |
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| `backup.image.tag` | Backup image tag | `0.6.0` |
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| `backup.extraArgs` | Additional arguments for cain | `[]` |
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| `backup.env` | Backup environment variables | AWS_REGION: `us-east-1` |
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| `backup.resources` | Backup CPU/Memory resource requests/limits | Memory: `1Gi`, CPU: `1` |
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| `backup.destination` | Destination to store backup artifacts | `s3://bucket/cassandra` |
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| `backup.google.serviceAccountSecret` | Secret containing credentials if GCS is used as destination | |
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| `exporter.enabled` | Enable Cassandra exporter | `false` |
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| `exporter.servicemonitor` | Enable ServiceMonitor for exporter | `true` |
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| `exporter.additionalLabels` | Additional labels for Service Monitor | `{}` |
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| `exporter.image.repo` | Exporter image repository | `criteord/cassandra_exporter` |
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| `exporter.image.tag` | Exporter image tag | `2.0.2` |
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| `exporter.port` | Exporter port | `5556` |
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| `exporter.jvmOpts` | Exporter additional JVM options | |
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| `exporter.resources` | Exporter CPU/Memory resource requests/limits | `{}` |
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| `affinity` | Kubernetes node affinity | `{}` |
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| `tolerations` | Kubernetes node tolerations | `[]` |
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## Scale cassandra
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When you want to change the cluster size of your cassandra, you can use the helm upgrade command.
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```bash
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helm upgrade --set config.cluster_size=5 cassandra incubator/cassandra
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```
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## Get cassandra status
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You can get your cassandra cluster status by running the command
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```bash
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kubectl exec -it --namespace cassandra $(kubectl get pods --namespace cassandra -l app=cassandra-cassandra -o jsonpath='{.items[0].metadata.name}') nodetool status
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```
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Output
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```bash
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Datacenter: asia-east1
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======================
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Status=Up/Down
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-- Address Load Tokens Owns (effective) Host ID Rack
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UN 10.8.1.11 108.45 KiB 256 66.1% 410cc9da-8993-4dc2-9026-1dd381874c54 a
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UN 10.8.4.12 84.08 KiB 256 68.7% 96e159e1-ef94-406e-a0be-e58fbd32a830 c
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UN 10.8.3.6 103.07 KiB 256 65.2% 1a42b953-8728-4139-b070-b855b8fff326 b
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```
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## Benchmark
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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
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```bash
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kubectl exec -it --namespace cassandra $(kubectl get pods --namespace cassandra -l app=cassandra-cassandra -o jsonpath='{.items[0].metadata.name}') cassandra-stress
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```
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Example of `cassandra-stress` argument
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- Run both read and write with ration 9:1
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- Operator total 1 million keys with uniform distribution
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- Use QUORUM for read/write
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- Generate 50 threads
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- Generate result in graph
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- Use NetworkTopologyStrategy with replica factor 2
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```bash
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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)"
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```
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