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Monitoring MongoDB 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 MongoDB 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 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
monitoringto deploy the prometheus operator helm chart. We are going to deploy database indemonamespace.$ 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/mongodb folder in GitHub repository kubedb/docs.
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.labels field of MongoDB 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 REPLICAS AGE
monitoring prometheus-kube-prometheus-prometheus v2.24.0 1 6h48m
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: "2021-03-09T10:47:17Z"
generation: 1
labels:
app: kube-prometheus-stack-prometheus
app.kubernetes.io/managed-by: Helm
chart: kube-prometheus-stack-13.13.0
heritage: Helm
release: prometheus
managedFields:
- apiVersion: monitoring.coreos.com/v1
fieldsType: FieldsV1
fieldsV1:
f:metadata:
f:annotations:
.: {}
f:meta.helm.sh/release-name: {}
f:meta.helm.sh/release-namespace: {}
f:labels:
.: {}
f:app: {}
f:app.kubernetes.io/managed-by: {}
f:chart: {}
f:heritage: {}
f:release: {}
f:spec:
.: {}
f:alerting:
.: {}
f:alertmanagers: {}
f:enableAdminAPI: {}
f:externalUrl: {}
f:image: {}
f:listenLocal: {}
f:logFormat: {}
f:logLevel: {}
f:paused: {}
f:podMonitorNamespaceSelector: {}
f:podMonitorSelector:
.: {}
f:matchLabels:
.: {}
f:release: {}
f:portName: {}
f:probeNamespaceSelector: {}
f:probeSelector:
.: {}
f:matchLabels:
.: {}
f:release: {}
f:replicas: {}
f:retention: {}
f:routePrefix: {}
f:ruleNamespaceSelector: {}
f:ruleSelector:
.: {}
f:matchLabels:
.: {}
f:app: {}
f:release: {}
f:securityContext:
.: {}
f:fsGroup: {}
f:runAsGroup: {}
f:runAsNonRoot: {}
f:runAsUser: {}
f:serviceAccountName: {}
f:serviceMonitorNamespaceSelector: {}
f:serviceMonitorSelector:
.: {}
f:matchLabels:
.: {}
f:release: {}
f:shards: {}
f:version: {}
manager: Go-http-client
operation: Update
time: "2021-03-09T10:47:17Z"
name: prometheus-kube-prometheus-prometheus
namespace: monitoring
resourceVersion: "100084"
selfLink: /apis/monitoring.coreos.com/v1/namespaces/monitoring/prometheuses/prometheus-kube-prometheus-prometheus
uid: 4b7a8c5b-09c4-4858-8232-13cbb71c766b
spec:
alerting:
alertmanagers:
- apiVersion: v2
name: prometheus-kube-prometheus-alertmanager
namespace: monitoring
pathPrefix: /
port: web
enableAdminAPI: false
externalUrl: http://prometheus-kube-prometheus-prometheus.monitoring:9090
image: quay.io/prometheus/prometheus:v2.24.0
listenLocal: false
logFormat: logfmt
logLevel: info
paused: false
podMonitorNamespaceSelector: {}
podMonitorSelector:
matchLabels:
release: prometheus
portName: web
probeNamespaceSelector: {}
probeSelector:
matchLabels:
release: prometheus
replicas: 1
retention: "10d"
routePrefix: /
ruleNamespaceSelector: {}
ruleSelector:
matchLabels:
app: kube-prometheus-stack
release: prometheus
securityContext:
fsGroup: 2000
runAsGroup: 2000
runAsNonRoot: true
runAsUser: 1000
serviceAccountName: prometheus-kube-prometheus-prometheus
serviceMonitorNamespaceSelector: {}
serviceMonitorSelector:
matchLabels:
release: prometheus
shards: 1
version: v2.24.0
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.labels field of MongoDB crd.
Deploy MongoDB with Monitoring Enabled
At first, let’s deploy an MongoDB database with monitoring enabled. Below is the MongoDB object that we are going to create.
apiVersion: kubedb.com/v1alpha2
kind: MongoDB
metadata:
name: coreos-prom-mgo
namespace: demo
spec:
version: "4.2.3"
terminationPolicy: WipeOut
storage:
storageClassName: "standard"
accessModes:
- ReadWriteOnce
resources:
requests:
storage: 1Gi
monitor:
agent: prometheus.io/operator
prometheus:
serviceMonitor:
labels:
release: prometheus
interval: 10s
Here,
monitor.agent: prometheus.io/operatorindicates that we are going to monitor this server using Prometheus operator.monitor.prometheus.namespace: monitoringspecifies that KubeDB should createServiceMonitorinmonitoringnamespace.monitor.prometheus.labelsspecifies that KubeDB should createServiceMonitorwith these labels.monitor.prometheus.intervalindicates that the Prometheus server should scrape metrics from this database with 10 seconds interval.
Let’s create the MongoDB object that we have shown above,
$ kubectl create -f https://github.com/kubedb/docs/raw/v2021.09.09/docs/examples/mongodb/monitoring/coreos-prom-mgo.yaml
mongodb.kubedb.com/coreos-prom-mgo created
Now, wait for the database to go into Running state.
$ kubectl get mg -n demo coreos-prom-mgo
NAME VERSION STATUS AGE
coreos-prom-mgo 4.2.3 Ready 34s
KubeDB will create a separate stats service with name {MongoDB crd name}-stats for monitoring purpose.
$ kubectl get svc -n demo --selector="app.kubernetes.io/instance=coreos-prom-mgo"
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
coreos-prom-mgo ClusterIP 10.96.150.171 <none> 27017/TCP 84s
coreos-prom-mgo-pods ClusterIP None <none> 27017/TCP 84s
coreos-prom-mgo-stats ClusterIP 10.96.218.41 <none> 56790/TCP 64s
Here, coreos-prom-mgo-stats service has been created for monitoring purpose.
Let’s describe this stats service.
$ kubectl describe svc -n demo coreos-prom-mgo-stats
Name: coreos-prom-mgo-stats
Namespace: demo
Labels: app.kubernetes.io/instance=coreos-prom-mgo
app.kubernetes.io/managed-by=kubedb.com
app.kubernetes.io/name=mongodbs.kubedb.com
kubedb.com/role=stats
Annotations: monitoring.appscode.com/agent: prometheus.io/operator
Selector: app.kubernetes.io/instance=coreos-prom-mgo,app.kubernetes.io/managed-by=kubedb.com,app.kubernetes.io/name=mongodbs.kubedb.com
Type: ClusterIP
IP Families: <none>
IP: 10.96.218.41
IPs: <none>
Port: metrics 56790/TCP
TargetPort: metrics/TCP
Endpoints: 10.244.0.110:56790
Session Affinity: None
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 coreos-prom-mgo-stats service. Verify that the ServiceMonitor crd has been created.
$ kubectl get servicemonitor -n demo
NAME AGE
coreos-prom-mgo-stats 2m40s
Let’s verify that the ServiceMonitor has the label that we had specified in spec.monitor section of MongoDB crd.
$ kubectl get servicemonitor -n demo coreos-prom-mgo-stats -o yaml
apiVersion: monitoring.coreos.com/v1
kind: ServiceMonitor
metadata:
creationTimestamp: "2021-03-09T17:40:16Z"
generation: 1
labels:
app.kubernetes.io/component: database
app.kubernetes.io/instance: coreos-prom-mgo
app.kubernetes.io/managed-by: kubedb.com
app.kubernetes.io/name: mongodbs.kubedb.com
release: prometheus
managedFields:
- apiVersion: monitoring.coreos.com/v1
fieldsType: FieldsV1
fieldsV1:
f:metadata:
f:labels:
.: {}
f:app.kubernetes.io/component: {}
f:app.kubernetes.io/instance: {}
f:app.kubernetes.io/managed-by: {}
f:app.kubernetes.io/name: {}
f:release: {}
f:ownerReferences: {}
f:spec:
.: {}
f:endpoints: {}
f:namespaceSelector:
.: {}
f:matchNames: {}
f:selector:
.: {}
f:matchLabels:
.: {}
f:app.kubernetes.io/instance: {}
f:app.kubernetes.io/managed-by: {}
f:app.kubernetes.io/name: {}
f:kubedb.com/role: {}
manager: mg-operator
operation: Update
time: "2021-03-09T17:40:16Z"
name: coreos-prom-mgo-stats
namespace: demo
ownerReferences:
- apiVersion: v1
blockOwnerDeletion: true
controller: true
kind: Service
name: coreos-prom-mgo-stats
uid: 906358eb-90dc-4a06-b9d3-89f557ad6ef4
resourceVersion: "184540"
selfLink: /apis/monitoring.coreos.com/v1/namespaces/demo/servicemonitors/coreos-prom-mgo-stats
uid: b0df2b5e-b6dd-4e8b-bf48-9da14f099d83
spec:
endpoints:
- bearerTokenSecret:
key: ""
honorLabels: true
interval: 10s
path: /metrics
port: metrics
namespaceSelector:
matchNames:
- demo
selector:
matchLabels:
app.kubernetes.io/instance: coreos-prom-mgo
app.kubernetes.io/managed-by: kubedb.com
app.kubernetes.io/name: mongodbs.kubedb.com
kubedb.com/role: stats
Notice that the ServiceMonitor has label release: prometheus that we had specified in MongoDB crd.
Also notice that the ServiceMonitor has selector which match the labels we have seen in the coreos-prom-mgo-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=prometheus
NAME READY STATUS RESTARTS AGE
prometheus-prometheus-kube-prometheus-prometheus-0 2/2 Running 1 6h58m
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-prometheus-kube-prometheus-prometheus-0 pod,
$ kubectl port-forward -n monitoring prometheus-prometheus-kube-prometheus-prometheus-0 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 coreos-prom-mgo-stats service as one of the targets.
Check the endpoint and service labels marked by the red rectangles. 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 cleanup the Kubernetes resources created by this tutorial, run following commands
kubectl delete -n demo mg/coreos-prom-mgo
kubectl delete ns demo
Next Steps
- Monitor your MongoDB database with KubeDB using out-of-the-box builtin-Prometheus.
- Detail concepts of MongoDB object.
- Detail concepts of MongoDBVersion object.
- Backup and Restore process of MongoDB databases using Stash.
- Initialize MongoDB with Script.
- Use private Docker registry to deploy MongoDB with KubeDB.
- Want to hack on KubeDB? Check our contribution guidelines.