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Using Prometheus (CoreOS operator) with KubeDB
This tutorial will show you how to monitor KubeDB databases using Prometheus via CoreOS Prometheus Operator.
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 by using Minikube.
Now, install KubeDB cli on your workstation and KubeDB operator in your cluster following the steps here.
Note: The yaml files that are used in this tutorial are stored in docs/examples folder in GitHub repository kubedb/cli.
Deploy CoreOS-Prometheus Operator
Run the following command to deploy CoreOS-Prometheus operator.
$ kubectl create -f https://raw.githubusercontent.com/kubedb/cli/0.9.0/docs/examples/monitoring/coreos-operator/demo-0.yaml
namespace/demo created
clusterrole.rbac.authorization.k8s.io/prometheus-operator created
serviceaccount/prometheus-operator created
clusterrolebinding.rbac.authorization.k8s.io/prometheus-operator created
deployment.extensions/prometheus-operator created
Wait for running the Deployment’s Pods.
$ kubectl get pods -n demo
NAME READY STATUS RESTARTS AGE
prometheus-operator-857455484c-q4qlr 1/1 Running 0 21s
This CoreOS-Prometheus operator will create some supported Custom Resource Definition (CRD).
$ kubectl get crd
NAME AGE
alertmanagers.monitoring.coreos.com 11m
prometheuses.monitoring.coreos.com 11m
servicemonitors.monitoring.coreos.com 11m
Once the Prometheus operator CRDs are registered, run the following command to create a Prometheus.
$ kubectl create -f https://raw.githubusercontent.com/kubedb/cli/0.9.0/docs/examples/monitoring/coreos-operator/demo-1.yaml
clusterrole.rbac.authorization.k8s.io/prometheus created
serviceaccount/prometheus created
clusterrolebinding.rbac.authorization.k8s.io/prometheus created
prometheus.monitoring.coreos.com/prometheus created
service/prometheus created
# Verify RBAC stuffs
$ kubectl get clusterroles
NAME AGE
prometheus 48s
prometheus-operator 1m
$ kubectl get clusterrolebindings
NAME AGE
prometheus 7s
prometheus-operator 25s
$ kubectl get serviceaccounts -n demo
NAME SECRETS AGE
default 1 5m
prometheus 1 4m
prometheus-operator 1 5m
Prometheus Dashboard
Now to open prometheus dashboard on Browser:
$ kubectl get svc -n demo
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
prometheus LoadBalancer 10.104.95.211 <pending> 9090:30900/TCP 5s
prometheus-operated ClusterIP None <none> 9090/TCP 5s
$ minikube ip
192.168.99.100
$ minikube service prometheus -n demo --url
http://192.168.99.100:30900
Now, open your browser and go to the following URL: http://{minikube-ip}:{prometheus-svc-nodeport} to visit Prometheus Dashboard. According to the above example, this URL will be http://192.168.99.100:30900.
If you are not using minikube, browse prometheus dashboard using following address http://{Node's ExternalIP}:{NodePort of prometheus-service}.
Find out required label for ServiceMonitor
First, check created objects of Prometheus kind.
$ kubectl get prometheus --all-namespaces
NAMESPACE NAME AGE
demo prometheus 20m
Now if we see the full spec of prometheus of Prometheus kind, we will see a field called serviceMonitorSelector. The value of matchLabels under serviceMonitorSelector part, is the required label for KubeDB monitoring spec monitor.prometheus.labels.
$ kubectl get prometheus -n demo prometheus -o yaml
apiVersion: monitoring.coreos.com/v1
kind: Prometheus
metadata:
creationTimestamp: 2018-11-15T10:40:57Z
generation: 1
name: prometheus
namespace: demo
resourceVersion: "1661"
selfLink: /apis/monitoring.coreos.com/v1/namespaces/demo/prometheuses/prometheus
uid: ef59e6e6-e8c2-11e8-8e44-08002771fd7b
spec:
resources:
requests:
memory: 400Mi
serviceAccountName: prometheus
serviceMonitorSelector:
matchLabels:
app: kubedb
version: v1.7.0
In this tutorial, the required label is app: kubedb.
Monitor Memcached with CoreOS Prometheus
KubeDB implements a Memcached CRD to define the specification of a Memcached database. Below is the Memcached object created in this tutorial.
apiVersion: kubedb.com/v1alpha1
kind: Memcached
metadata:
name: memcd-mon-coreos
namespace: demo
spec:
replicas: 3
version: "1.5.4-v1"
podTemplate:
spec:
resources:
limits:
cpu: 500m
memory: 128Mi
requests:
cpu: 250m
memory: 64Mi
monitor:
agent: prometheus.io/coreos-operator
prometheus:
namespace: demo
labels:
app: kubedb
interval: 10s
The Memcached CRD object contains monitor field in it’s spec. It is also possible to add CoreOS-Prometheus monitor to an existing Memcached database by adding the below part in it’s spec field.
Here, spec.monitor.prometheus.labels is the serviceMonitorSelector that we found earlier.
spec:
monitor:
agent: prometheus.io/coreos-operator
prometheus:
namespace: demo
labels:
app: kubedb
interval: 10s
| Keys | Value | Description |
|---|---|---|
spec.monitor.agent | string | Required. Indicates the monitoring agent used. Only valid value currently is coreos-prometheus-operator |
spec.monitor.prometheus.namespace | string | Required. Indicates namespace where service monitors are created. This must be the same namespace of the Prometheus instance. |
spec.monitor.prometheus.labels | map | Required. Indicates labels applied to service monitor. |
spec.monitor.prometheus.interval | string | Optional. Indicates the scrape interval for database exporter endpoint (eg, ’10s') |
spec.monitor.prometheus.port | int | Optional. Indicates the port for database exporter endpoint (default is 56790) |
Known Limitations: If the database password is updated, exporter must be restarted to use the new credentials. This issue is tracked here.
Run the following command to deploy the above Memcached CRD object.
$ kubedb create -f https://raw.githubusercontent.com/kubedb/cli/0.9.0/docs/examples/memcached/monitoring/coreos-operator/demo-1.yaml
memcached.kubedb.com/memcd-mon-coreos created
Here,
spec.monitorspecifies that CoreOS Prometheus operator is used to monitor this database instance. A ServiceMonitor should be created in thedemonamespace with labelapp=kubedb. The exporter endpoint should be scrapped every 10 seconds.
KubeDB will create a separate stats service with name <memcached-crd-name>-stats for monitoring purpose. KubeDB operator will configure this monitoring service once the Memcached is successfully running.
$ kubedb get mc -n demo
NAME VERSION STATUS AGE
memcd-mon-coreos 1.5.4-v1 Running 1m
$ kubedb describe mc -n demo memcd-mon-coreos
Name: memcd-mon-coreos
Namespace: demo
CreationTimestamp: Wed, 03 Oct 2018 16:46:01 +0600
Labels: <none>
Annotations: <none>
Replicas: 3 total
Status: Running
Deployment:
Name: memcd-mon-coreos
CreationTimestamp: Wed, 03 Oct 2018 16:46:03 +0600
Labels: kubedb.com/kind=Memcached
kubedb.com/name=memcd-mon-coreos
Annotations: deployment.kubernetes.io/revision=1
Replicas: 3 desired | 3 updated | 3 total | 3 available | 0 unavailable
Pods Status: 3 Running / 0 Waiting / 0 Succeeded / 0 Failed
Service:
Name: memcd-mon-coreos
Labels: kubedb.com/kind=Memcached
kubedb.com/name=memcd-mon-coreos
Annotations: <none>
Type: ClusterIP
IP: 10.101.172.16
Port: db 11211/TCP
TargetPort: db/TCP
Endpoints: 172.17.0.6:11211,172.17.0.7:11211,172.17.0.8:11211
Service:
Name: memcd-mon-coreos-stats
Labels: kubedb.com/kind=Memcached
kubedb.com/name=memcd-mon-coreos
Annotations: monitoring.appscode.com/agent=prometheus.io/coreos-operator
Type: ClusterIP
IP: 10.99.230.104
Port: prom-http 56790/TCP
TargetPort: prom-http/TCP
Endpoints: 172.17.0.6:56790,172.17.0.7:56790,172.17.0.8:56790
Monitoring System:
Agent: prometheus.io/coreos-operator
Prometheus:
Port: 56790
Namespace: demo
Labels: app=kubedb
Interval: 10s
No Snapshots.
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal Successful 2m Memcached operator Successfully created Service
Normal Successful 1m Memcached operator Successfully created StatefulSet
Normal Successful 1m Memcached operator Successfully created Memcached
Normal Successful 1m Memcached operator Successfully created stats service
Normal Successful 1m Memcached operator Successfully patched StatefulSet
Normal Successful 1m Memcached operator Successfully patched Memcached
Since spec.monitoring was configured, a ServiceMonitor object is created accordingly. You can verify it running the following commands:
$ kubectl get servicemonitor -n demo
NAME AGE
kubedb-demo-memcd-mon-coreos 1m
$ kubectl get servicemonitor -n demo kubedb-demo-memcd-mon-coreos -o yaml
apiVersion: monitoring.coreos.com/v1
kind: ServiceMonitor
metadata:
creationTimestamp: 2018-10-03T10:46:48Z
generation: 1
labels:
app: kubedb
monitoring.appscode.com/service: memcd-mon-coreos-stats.demo
name: kubedb-demo-memcd-mon-coreos
namespace: demo
resourceVersion: "28890"
selfLink: /apis/monitoring.coreos.com/v1/namespaces/demo/servicemonitors/kubedb-demo-memcd-mon-coreos
uid: a0b48fd2-c6f9-11e8-8ebc-0800275bbbee
spec:
endpoints:
- interval: 10s
path: /metrics
port: prom-http
targetPort: 0
namespaceSelector:
matchNames:
- demo
selector:
matchLabels:
kubedb.com/kind: Memcached
kubedb.com/name: memcd-mon-coreos
Now, if you go the Prometheus Dashboard, you should see that this database endpoint as one of the targets.
Cleaning up
To cleanup the Kubernetes resources created by this tutorial, run:
kubectl patch -n demo mc/memcd-mon-coreos -p '{"spec":{"terminationPolicy":"WipeOut"}}' --type="merge"
kubectl delete -n demo mc/memcd-mon-coreos
kubectl patch -n demo drmn/memcd-mon-coreos -p '{"spec":{"wipeOut":true}}' --type="merge"
kubectl delete -n demo drmn/memcd-mon-coreos
kubectl delete -f https://raw.githubusercontent.com/kubedb/cli/0.9.0/docs/examples/monitoring/coreos-operator/demo-1.yaml
kubectl delete -f https://raw.githubusercontent.com/kubedb/cli/0.9.0/docs/examples/monitoring/coreos-operator/demo-0.yaml
kubectl delete ns demo
Next Steps
- Monitor your Memcached database with KubeDB using out-of-the-box builtin-Prometheus.
- Detail concepts of Memcached object.
- Use private Docker registry to deploy Memcached with KubeDB.
- Want to hack on KubeDB? Check our contribution guidelines.