Kubernetes: Cassandra(stateful set) deployment on GCP - cassandra

Question

Has anyone tried deploying Cassandra (POC) on GCP using kubernetes (not GKE). If so can you please share info on how to get it working?

Answer 1

You could start by looking at IBM's Scalable-Cassandra-deployment-on-Kubernetes.
For seeds discovery you can use a headless service, similar to this Multi-node Cassandra Cluster Made Easy with Kubernetes.
Some difficulties:
fast local storage for K8s is still in beta; of course, you can use what k8s already has; there are some users reporting that they use Ceph RBD with 8 C* nodes each of them having 2TB of data on K8s.
at some point in time you will realize that you need a C* operator - here is some good startup - Instaclustr's Cassandra Operator and Pantheon Systems' Cassandra Operator
you need a way to scale in gracefully stateful applications (should be also covered by the operator; this is a solution if you don't want an operator, but you still need to use a controller).
You could also check the Cassandra mailing list, since there are people there already using Cassandra over K8s in production.

Answer 2

I have implemented cassandra on kubernetes. Please find my deployment and service yaml files:
apiVersion: v1
kind: Service
metadata:
labels:
app: cassandra
name: cassandra
spec:
clusterIP: None
ports:
- port: 9042
selector:
app: cassandra
---
apiVersion: apps/v1beta2
kind: StatefulSet
metadata:
name: cassandra
labels:
app: cassandra
spec:
serviceName: cassandra
replicas: 3
updateStrategy:
type: RollingUpdate
selector:
matchLabels:
app: cassandra
template:
metadata:
labels:
app: cassandra
spec:
terminationGracePeriodSeconds: 1800
containers:
- name: cassandra
image: gcr.io/google-samples/cassandra:v12
imagePullPolicy: Always
ports:
- containerPort: 7000
name: intra-node
- containerPort: 7001
name: tls-intra-node
- containerPort: 7199
name: jmx
- containerPort: 9042
name: cql
resources:
limits:
cpu: "500m"
memory: 1Gi
requests:
cpu: "500m"
memory: 1Gi
securityContext:
capabilities:
add:
- IPC_LOCK
lifecycle:
preStop:
exec:
command:
- /bin/sh
- -c
- nodetool drain
env:
- name: MAX_HEAP_SIZE
value: 512M
- name: HEAP_NEWSIZE
value: 100M
- name: CASSANDRA_SEEDS
value: "cassandra-0.cassandra.default.svc.cluster.local"
- name: CASSANDRA_CLUSTER_NAME
value: "K8Demo"
- name: CASSANDRA_DC
value: "DC1-K8Demo"
- name: CASSANDRA_RACK
value: "Rack1-K8Demo"
- name: POD_IP
valueFrom:
fieldRef:
fieldPath: status.podIP
readinessProbe:
exec:
command:
- /bin/bash
- -c
- /ready-probe.sh
initialDelaySeconds: 15
timeoutSeconds: 5
volumeMounts:
- name: cassandra-data
mountPath: /cassandra_data
volumeClaimTemplates:
- metadata:
name: cassandra-data
spec:
accessModes: [ "ReadWriteOnce" ]
storageClassName: "fast"
resources:
requests:
storage: 5Gi
Hope this helps.

Answer 3

Use Helm:
On Mac:
brew install helm#2
brew link --force helm#2
helm init
To Avoid Kubernetes Helm permission Hell:
from: https://github.com/helm/helm/issues/2224:
kubectl create serviceaccount --namespace kube-system tiller
kubectl create clusterrolebinding tiller-cluster-rule --clusterrole=cluster-admin --serviceaccount=kube-system:tiller
Cassandra
incubator:
helm repo add https://github.com/helm/charts/tree/master/incubator/cassandra
helm install --namespace "cassandra" -n "cassandra" incubator/cassandra
helm status "cassandra"
helm delete --purge "cassandra"
bitnami:
helm repo add bitnami https://charts.bitnami.com/bitnami
helm install --namespace "cassandra" -n "my-deployment" bitnami/cassandra
helm status "my-deployment"
helm delete --purge "my-deployment"