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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.
To keep things isolated, this tutorial uses a separate namespace called demo throughout this tutorial.
Note that the yaml files that are used in this tutorial, stored in docs/examples folder in GitHub repository kubedb/cli.
Deploy CoreOS-Prometheus Operator
In RBAC enabled cluster
If RBAC is enabled, Run the following command to prepare your cluster for this tutorial:
$ kubectl create -f https://raw.githubusercontent.com/kubedb/cli/0.8.0-beta.2/docs/examples/monitoring/coreos-operator/rbac/demo-0.yaml
namespace "demo" created
clusterrole "prometheus-operator" created
serviceaccount "prometheus-operator" created
clusterrolebinding "prometheus-operator" created
deployment "prometheus-operator" created
$ kubectl get pods -n demo --watch
NAME READY STATUS RESTARTS AGE
prometheus-operator-79cb9dcd4b-2njgq 1/1 Running 0 2m
$ 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/0.8.0-beta.2/docs/examples/monitoring/coreos-operator/rbac/demo-1.yaml
clusterrole "prometheus" created
serviceaccount "prometheus" created
clusterrolebinding "prometheus" created
prometheus "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
In RBAC *not* enabled cluster
If RBAC is not enabled, Run the following command to prepare your cluster for this tutorial:
$ kubectl create -f https://raw.githubusercontent.com/kubedb/cli/0.8.0-beta.2/docs/examples/monitoring/coreos-operator/demo-0.yaml
namespace "demo" created
deployment "prometheus-operator" created
$ kubectl get pods -n demo --watch
NAME READY STATUS RESTARTS AGE
prometheus-operator-5dcd844486-2kgwv 0/1 ContainerCreating 0 9s
prometheus-operator-5dcd844486-2kgwv 1/1 Running 0 28s
$ kubectl get crd
NAME AGE
alertmanagers.monitoring.coreos.com 45s
prometheuses.monitoring.coreos.com 44s
servicemonitors.monitoring.coreos.com 44s
Once the Prometheus operator CRDs are registered, run the following command to create a Prometheus.
$ kubectl create -f https://raw.githubusercontent.com/kubedb/cli/0.8.0-beta.2/docs/examples/monitoring/coreos-operator/demo-1.yaml
prometheus "prometheus" created
service "prometheus" created
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.
Create a Memcached database
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
doNotPause: true
resources:
requests:
memory: 64Mi
cpu: 250m
limits:
memory: 128Mi
cpu: 500m
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.
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/0.8.0-beta.2/docs/examples/memcached/monitoring/coreos-operator/demo-1.yaml
validating "https://raw.githubusercontent.com/kubedb/cli/0.8.0-beta.2/docs/examples/memcached/monitoring/coreos-operator/demo-1.yaml"
memcached "memcd-mon-coreos" created
Here,
spec.versionis the version of Memcached database. In this tutorial, a Memcached 1.5.4 database is going to be created.spec.resourceis an optional field that specifies how much CPU and memory (RAM) each Container needs. To learn details about Managing Compute Resources for Containers, please visit 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 operator watches for Memcached objects using Kubernetes api. When a Memcached object is created, KubeDB operator will create a new Deployment and a ClusterIP Service with the matching crd name.
$ kubedb get mc -n demo
NAME STATUS AGE
memcd-mon-coreos Running 1m
$ kubedb describe mc -n demo memcd-mon-coreos
Name: memcd-mon-coreos
Namespace: demo
StartTimestamp: Tue, 13 Feb 2018 12:17:21 +0600
Status: Running
Deployment:
Name: memcd-mon-coreos
Replicas: 3 current / 3 desired
CreationTimestamp: Tue, 13 Feb 2018 12:17:22 +0600
Pods Status: 3 Running / 0 Waiting / 0 Succeeded / 0 Failed
Service:
Name: memcd-mon-coreos
Type: ClusterIP
IP: 10.104.166.35
Port: db 11211/TCP
Port: prom-http 56790/TCP
Monitoring System:
Agent: prometheus.io/coreos-operator
Prometheus:
Namespace: demo
Labels: app=kubedb
Interval: 10s
Events:
FirstSeen LastSeen Count From Type Reason Message
--------- -------- ----- ---- -------- ------ -------
1m 1m 1 Memcached operator Normal Successful Successfully patched Deployment
1m 1m 1 Memcached operator Normal Successful Successfully patched Memcached
1m 1m 1 Memcached operator Normal Successful Successfully created Deployment
1m 1m 1 Memcached operator Normal Successful Successfully created Memcached
1m 1m 1 Memcached operator Normal Successful Successfully created Service
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:
clusterName: ""
creationTimestamp: 2018-02-13T06:17:36Z
labels:
app: kubedb
monitoring.appscode.com/service: memcd-mon-coreos.demo
name: kubedb-demo-memcd-mon-coreos
namespace: demo
resourceVersion: "4743"
selfLink: /apis/monitoring.coreos.com/v1/namespaces/demo/servicemonitors/kubedb-demo-memcd-mon-coreos
uid: 961a507b-1085-11e8-801e-080027e82bd4
spec:
endpoints:
- interval: 10s
path: /kubedb.com/v1alpha1/namespaces/demo/memcacheds/memcd-mon-coreos/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:
$ kubedb delete mc,drmn -n demo --all --force
# In rbac enabled cluster,
# $ kubectl delete clusterrolebindings prometheus-operator prometheus
# $ kubectl delete clusterrole prometheus-operator prometheus
$ kubectl delete ns demo
namespace "demo" deleted
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.
- Wondering what features are coming next? Please visit here.
- Want to hack on KubeDB? Check our contribution guidelines.