KubeDB

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Monitoring Cassandra Using Prometheus operator

Prometheus operator provides simple and Kubernetes native way to deploy and configure Prometheus server. This tutorial will show you how to use Prometheus operator to monitor Cassandra database deployed with KubeDB.

Before You Begin

  • At first, you need to have a Kubernetes cluster, and the kubectl command-line tool must be configured to communicate with your cluster. If you do not already have a cluster, you can create one locally by using kind.

  • To learn how Prometheus monitoring works with KubeDB in general, please visit here.

  • We need a Prometheus operator instance running. If you don’t already have a running instance, you can deploy one using this helm chart here.

  • To keep Prometheus resources isolated, we are going to use a separate namespace called monitoring to deploy the prometheus operator helm chart. Alternatively, you can use --create-namespace flag while deploying prometheus. We are going to deploy database in demo namespace.

    $ kubectl create ns monitoring
namespace/monitoring created

$ kubectl create ns demo
namespace/demo created

Note: YAML files used in this tutorial are stored in docs/examples/cassandra folder in GitHub repository kubedb/docs.

Configuration

Step 1 (kube-prometheus-stack) is required to follow this tutorial. Step 2 (Panopticon) is not needed for the Prometheus Operator / ServiceMonitor scraping documented on this page — install it only if you also plan to use the KubeDB Grafana dashboards’ status panels, or phase-based Alerting. If you have already completed the step(s) you need in another guide, skip ahead.

Step 1: Deploy kube-prometheus-stack

kube-prometheus-stack installs Prometheus, Prometheus Operator, Alertmanager, and Grafana together. This is the recommended way to get the full monitoring stack on Kubernetes. This is where Grafana itself gets installed for this tutorial track — the Grafana Dashboard guide’s “Access Grafana” step assumes it’s already running from here; you do not install Grafana again there.

Add the prometheus-community Helm repo and install:

$ helm repo add prometheus-community https://prometheus-community.github.io/helm-charts
$ helm repo update

$ helm upgrade --install prometheus prometheus-community/kube-prometheus-stack \
  --namespace monitoring \
  --set grafana.image.tag=7.5.5

Wait for all pods to be ready:

$ kubectl get pods -n monitoring
NAME                                                   READY   STATUS    RESTARTS   AGE
alertmanager-prometheus-kube-prometheus-alertmanager-0 2/2     Running   0          2m
prometheus-grafana-xxxx                                3/3     Running   0          2m
prometheus-kube-prometheus-operator-xxxx               1/1     Running   0          2m
prometheus-kube-prometheus-prometheus-0                2/2     Running   0          2m
prometheus-kube-state-metrics-xxxx                     1/1     Running   0          2m

Find the serviceMonitorSelector label that Prometheus uses to pick up ServiceMonitor objects. You will need this label when enabling monitoring on the Cassandra instance.

$ kubectl get prometheus -n monitoring -o jsonpath='{.items[0].spec.serviceMonitorSelector}'
{"matchLabels":{"release":"prometheus"}}

The label is release: prometheus.

Step 2: Install Panopticon (optional — only for Grafana dashboards & Alerting)

Panopticon is the Appscode operator that reads MetricsConfiguration objects (created by kubedb-metrics) and exposes them to Prometheus. It is not required for the Prometheus Operator / ServiceMonitor scraping covered on this page — skip it, and skip enabling kubedb-metrics too, if you only need raw metrics in Prometheus. Install it only if you also plan to use the phase/status panels of the KubeDB Grafana dashboards, or phase-based Alerting — and install it before enabling kubedb-metrics.

$ helm repo add appscode https://charts.appscode.com/stable/
$ helm repo update

$ helm upgrade --install panopticon appscode/panopticon \
  --version v2026.4.30 \
  --namespace kubeops --create-namespace \
  --set monitoring.enabled=true \
  --set monitoring.agent=prometheus.io/operator \
  --set monitoring.serviceMonitor.labels.release=prometheus \
  --set-file license=/path/to/kubedb-license.txt \
  --wait --timeout 5m0s

Verify panopticon is running:

$ kubectl get pods -n kubeops
NAME                          READY   STATUS    RESTARTS   AGE
panopticon-xxxx               1/1     Running   0          1m

Find out required labels for ServiceMonitor

We need to know the labels used to select ServiceMonitor by a Prometheus crd. We are going to provide these labels in spec.monitor.prometheus.serviceMonitor.labels field of Cassandra crd so that KubeDB creates ServiceMonitor object accordingly.

At first, let’s find out the available Prometheus server in our cluster.

$ kubectl get prometheus --all-namespaces
NAMESPACE    NAME                                    VERSION   DESIRED   READY   RECONCILED   AVAILABLE   AGE
monitoring   prometheus-kube-prometheus-prometheus   v3.4.2    1         1       True         True        7h43m

If you don’t have any Prometheus server running in your cluster, deploy one following the guide specified in Before You Begin section.

Now, let’s view the YAML of the available Prometheus server prometheus in monitoring namespace.

$ kubectl get prometheus -n monitoring prometheus-kube-prometheus-prometheus -o yaml
apiVersion: monitoring.coreos.com/v1
kind: Prometheus
metadata:
  annotations:
    meta.helm.sh/release-name: prometheus
    meta.helm.sh/release-namespace: monitoring
  creationTimestamp: "2025-07-24T04:20:17Z"
  finalizers:
  - monitoring.appscode.com/prometheus
  generation: 1
  labels:
    app: kube-prometheus-stack-prometheus
    app.kubernetes.io/instance: prometheus
    app.kubernetes.io/managed-by: Helm
    app.kubernetes.io/part-of: kube-prometheus-stack
    app.kubernetes.io/version: 75.9.0
    chart: kube-prometheus-stack-75.9.0
    heritage: Helm
    release: prometheus
  name: prometheus-kube-prometheus-prometheus
  namespace: monitoring
  resourceVersion: "49548"
  uid: aa50a17f-9e2e-4f0e-8898-af5dd7f90c9b
spec:
  affinity:
    podAntiAffinity:
      preferredDuringSchedulingIgnoredDuringExecution:
      - podAffinityTerm:
          labelSelector:
            matchExpressions:
            - key: app.kubernetes.io/name
              operator: In
              values:
              - prometheus
            - key: app.kubernetes.io/instance
              operator: In
              values:
              - prometheus-kube-prometheus-prometheus
          topologyKey: kubernetes.io/hostname
        weight: 100
  alerting:
    alertmanagers:
    - apiVersion: v2
      name: prometheus-kube-prometheus-alertmanager
      namespace: monitoring
      pathPrefix: /
      port: http-web
  automountServiceAccountToken: true
  enableAdminAPI: false
  enableOTLPReceiver: false
  evaluationInterval: 30s
  externalUrl: http://prometheus-kube-prometheus-prometheus.monitoring:9090
  hostNetwork: false
  image: quay.io/prometheus/prometheus:v3.4.2
  imagePullPolicy: IfNotPresent
  listenLocal: false
  logFormat: logfmt
  logLevel: info
  paused: false
  podMonitorNamespaceSelector: {}
  podMonitorSelector:
    matchLabels:
      release: prometheus
  portName: http-web
  probeNamespaceSelector: {}
  probeSelector:
    matchLabels:
      release: prometheus
  replicas: 1
  retention: 10d
  routePrefix: /
  ruleNamespaceSelector: {}
  ruleSelector:
    matchLabels:
      release: prometheus
  scrapeConfigNamespaceSelector: {}
  scrapeConfigSelector:
    matchLabels:
      release: prometheus
  scrapeInterval: 30s
  securityContext:
    fsGroup: 2000
    runAsGroup: 2000
    runAsNonRoot: true
    runAsUser: 1000
    seccompProfile:
      type: RuntimeDefault
  serviceAccountName: prometheus-kube-prometheus-prometheus
  serviceMonitorNamespaceSelector: {}
  serviceMonitorSelector:
    matchLabels:
      release: prometheus
  shards: 1
  tsdb:
    outOfOrderTimeWindow: 0s
  version: v3.4.2
  walCompression: true
status:
  availableReplicas: 1
  conditions:
  - lastTransitionTime: "2025-07-25T04:40:59Z"
    message: ""
    observedGeneration: 1
    reason: ""
    status: "True"
    type: Available
  - lastTransitionTime: "2025-07-25T04:40:59Z"
    message: ""
    observedGeneration: 1
    reason: ""
    status: "True"
    type: Reconciled
  paused: false
  replicas: 1
  selector: app.kubernetes.io/instance=prometheus-kube-prometheus-prometheus,app.kubernetes.io/managed-by=prometheus-operator,app.kubernetes.io/name=prometheus,operator.prometheus.io/name=prometheus-kube-prometheus-prometheus,prometheus=prometheus-kube-prometheus-prometheus
  shardStatuses:
  - availableReplicas: 1
    replicas: 1
    shardID: "0"
    unavailableReplicas: 0
    updatedReplicas: 1
  shards: 1
  unavailableReplicas: 0
  updatedReplicas: 1

Notice the spec.serviceMonitorSelector section. Here, release: prometheus label is used to select ServiceMonitor crd. So, we are going to use this label in spec.monitor.prometheus.serviceMonitor.labels field of Cassandra crd.

Deploy Cassandra with Monitoring Enabled

At first, let’s deploy a Cassandra database with monitoring enabled. Below is the Cassandra object that we are going to create.

apiVersion: kubedb.com/v1alpha2
kind: Cassandra
metadata:
  name: cassandra-prod
  namespace: demo
spec:
  version: 5.0.7
  topology:
    rack:
      - name: r0
        replicas: 2
        podTemplate:
          spec:
            containers:
              - name: cassandra
                resources:
                  limits:
                    memory: 2Gi
                    cpu: 2
                  requests:
                    memory: 1Gi
                    cpu: 1
        storage:
          accessModes:
            - ReadWriteOnce
          resources:
            requests:
              storage: 1Gi
        storageType: Durable
  deletionPolicy: WipeOut
  monitor:
    agent: "prometheus.io/operator"
    prometheus:
      serviceMonitor:
        labels:
          release: prometheus
        interval: 10s

Here,

  • monitor.agent: prometheus.io/operator indicates that we are going to monitor this server using Prometheus operator.
  • monitor.prometheus.serviceMonitor.labels specifies that KubeDB should create ServiceMonitor with these labels.
  • monitor.prometheus.interval indicates that the Prometheus server should scrape metrics from this database with 10 seconds interval.

Let’s create the cassandra object that we have shown above,

$ kubectl create -f https://github.com/kubedb/docs/raw/v2026.7.10/docs/examples/cassandra/monitoring/cas-with-monitoring.yaml
cassandras.kubedb.com/cassandra created

Now, wait for the database to go into Running state.

$  kubectl get cas -n demo cassandra-prod
NAME             TYPE                  VERSION   STATUS   AGE
cassandra-prod   kubedb.com/v1alpha2   5.0.3     Ready    17h

KubeDB will create a separate stats service with name {Cassandra crd name}-stats for monitoring purpose.

$ kubectl get svc -n demo --selector="app.kubernetes.io/instance=cassandra-prod"
NAME                          TYPE        CLUSTER-IP     EXTERNAL-IP   PORT(S)                               AGE
cassandra-prod                ClusterIP   10.96.232.61   <none>        9042/TCP,7000/TCP,7199/TCP,7001/TCP   17h
cassandra-prod-rack-r0-pods   ClusterIP   None           <none>        9042/TCP,7000/TCP,7199/TCP,7001/TCP   17h
cassandra-prod-stats          ClusterIP   10.96.189.65   <none>        56790/TCP                             17h

Here, cassandra-stats service has been created for monitoring purpose.

Let’s describe this stats service.

$ kubectl describe svc -n demo cassandra-prod-stats
Name:                     cassandra-prod-stats
Namespace:                demo
Labels:                   app.kubernetes.io/component=database
                          app.kubernetes.io/instance=cassandra-prod
                          app.kubernetes.io/managed-by=kubedb.com
                          app.kubernetes.io/name=cassandras.kubedb.com
                          kubedb.com/role=stats
Annotations:              monitoring.appscode.com/agent: prometheus.io/operator
Selector:                 app.kubernetes.io/instance=cassandra-prod,app.kubernetes.io/managed-by=kubedb.com,app.kubernetes.io/name=cassandras.kubedb.com
Type:                     ClusterIP
IP Family Policy:         SingleStack
IP Families:              IPv4
IP:                       10.96.189.65
IPs:                      10.96.189.65
Port:                     metrics  56790/TCP
TargetPort:               metrics/TCP
Endpoints:                10.244.0.19:8080,10.244.0.18:8080
Session Affinity:         None
Internal Traffic Policy:  Cluster
Events:                   <none>

Notice the Labels and Port fields. ServiceMonitor will use this information to target its endpoints.

KubeDB will also create a ServiceMonitor crd in demo namespace that select the endpoints of cassandra-stats service. Verify that the ServiceMonitor crd has been created.

$  kubectl get servicemonitor -n demo
NAME                   AGE
cassandra-prod-stats   17h

Let’s verify that the ServiceMonitor has the label that we had specified in spec.monitor section of Cassandra crd.

$ kubectl get servicemonitor -n demo cassandra-prod-stats -o yaml
apiVersion: monitoring.coreos.com/v1
kind: ServiceMonitor
metadata:
  creationTimestamp: "2025-07-24T11:51:13Z"
  generation: 1
  labels:
    app.kubernetes.io/component: database
    app.kubernetes.io/instance: cassandra-prod
    app.kubernetes.io/managed-by: kubedb.com
    app.kubernetes.io/name: cassandras.kubedb.com
    release: prometheus
  name: cassandra-prod-stats
  namespace: demo
  ownerReferences:
  - apiVersion: v1
    blockOwnerDeletion: true
    controller: true
    kind: Service
    name: cassandra-prod-stats
    uid: f162ee2b-7bf2-4c27-88ec-76ec95c1829f
  resourceVersion: "46434"
  uid: 294b03fc-acbf-4560-b940-ea1f1db2171b
spec:
  endpoints:
  - honorLabels: true
    interval: 10s
    path: /metrics
    port: metrics
  namespaceSelector:
    matchNames:
    - demo
  selector:
    matchLabels:
      app.kubernetes.io/component: database
      app.kubernetes.io/instance: cassandra-prod
      app.kubernetes.io/managed-by: kubedb.com
      app.kubernetes.io/name: cassandras.kubedb.com
      kubedb.com/role: stats

Notice that the ServiceMonitor has label release: prometheus that we had specified in Cassandra crd.

Also notice that the ServiceMonitor has selector which match the labels we have seen in the cassandra-prod-stats service. It also, target the metrics port that we have seen in the stats service.

Verify Monitoring Metrics

At first, let’s find out the respective Prometheus pod for prometheus Prometheus server.

$ kubectl get pod -n monitoring -l=app.kubernetes.io/name=prometheus
NAME                                                 READY   STATUS    RESTARTS      AGE
prometheus-prometheus-kube-prometheus-prometheus-0   2/2     Running   2 (18m ago)   24h

Prometheus server is listening to port 9090 of prometheus-prometheus-kube-prometheus-prometheus-0 pod. We are going to use port forwarding to access Prometheus dashboard.

Run following command on a separate terminal to forward the port 9090 of prometheus-kube-prometheus-prometheus service which is pointing to the prometheus pod,

$ kubectl port-forward -n monitoring svc/prometheus-kube-prometheus-prometheus 9090
Forwarding from 127.0.0.1:9090 -> 9090
Forwarding from [::1]:9090 -> 9090

Now, we can access the dashboard at localhost:9090. Open http://localhost:9090 in your browser. You should see metrics endpoint of cassandra-stats service as one of the targets.

Check the endpoint and service labels. It verifies that the target is our expected database. Now, you can view the collected metrics and create a graph from homepage of this Prometheus dashboard. You can also use this Prometheus server as data source for Grafana and create a beautiful dashboard with collected metrics.

Cleaning up

To clean up the Kubernetes resources created by this tutorial, run following commands

kubectl delete -n demo cas/cassandra-prod
kubectl delete ns demo

Next Steps

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