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Monitoring PgBouncer 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 PgBouncer 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.

  • To keep Prometheus resources isolated, we are going to use a separate namespace called monitoring to deploy respective monitoring resources. We are going to deploy database in demo namespace.

    $ kubectl create ns monitoring
    namespace/monitoring created
    
  • We need a Prometheus operator instance running. If you don’t already have a running instance, deploy one following the docs from here.

  • If you already don’t have a Prometheus server running, deploy one following tutorial from here.

Note: YAML files used in this tutorial are stored in docs/examples/pgbouncer 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 PgBouncer crd so that KubeDB creates ServiceMonitor object accordingly.

As a prerequisite, we need to have Prometheus operator running, and a prometheus server created to monitor PgBouncer exporter. In this tutorial we are going to use a prometheus server named promethus in monitoring namespace. You can use the following to install Prometheus operator.

$ kubectl apply -f https://raw.githubusercontent.com/appscode/third-party-tools/master/monitoring/prometheus/coreos-operator/artifacts/operator.yaml

Now, get a prometheus server up and running.

$ kubectl apply -f https://github.com/kubedb/docs/raw/v2020.11.12/docs/examples/pgbouncer/monitoring/coreos-prom-server.yaml

clusterrole.rbac.authorization.k8s.io/prometheus created
serviceaccount/prometheus created
clusterrolebinding.rbac.authorization.k8s.io/prometheus created
prometheus.monitoring.coreos.com/prometheus created

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


$ kubectl get prometheus --all-namespaces
NAMESPACE    NAME                                    AGE
default      tufted-rodent-prometheus-o-prometheus   3h42m
monitoring   prometheus                              18m

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

$ kubectl get prometheus -n monitoring prometheus -o yaml
apiVersion: monitoring.coreos.com/v1
kind: Prometheus
metadata:
  annotations:
    kubectl.kubernetes.io/last-applied-configuration: |
      {"apiVersion":"monitoring.coreos.com/v1","kind":"Prometheus","metadata":{"annotations":{},"labels":{"prometheus":"prometheus"},"name":"prometheus","namespace":"monitoring"},"spec":{"replicas":1,"resources":{"requests":{"memory":"400Mi"}},"serviceAccountName":"prometheus","serviceMonitorSelector":{"matchLabels":{"k8s-app":"prometheus"}}}}
  creationTimestamp: "2019-09-19T09:32:12Z"
  generation: 1
  labels:
    prometheus: prometheus
  name: prometheus
  namespace: monitoring
  resourceVersion: "38348"
  selfLink: /apis/monitoring.coreos.com/v1/namespaces/monitoring/prometheuses/prometheus
  uid: f9285974-3349-40e8-815a-8f50c3a8a4f5
spec:
  replicas: 1
  resources:
    requests:
      memory: 400Mi
  serviceAccountName: prometheus
  serviceMonitorSelector:
    matchLabels:
      k8s-app: prometheus

Notice the spec.serviceMonitorSelector section. Here, k8s-app: prometheus label is used to select ServiceMonitor crd. So, we are going to use this label in spec.monitor.prometheus.labels field of PgBouncer crd.

Deploy PgBouncer with Monitoring Enabled

We will need a PgBouncer with monitoring enabled. This PgBouncer needs to be connected to PostgreSQL database(s). You can get a PgBouncer setup with active connection(s) to PostgreSQL by following the quickstart guide. PgBouncer object in that guide didn’t come with monitoring. So we are going to enable monitoring in it. Below is the PgBouncer object that contains Prometheus operator based monitoring:

apiVersion: kubedb.com/v1alpha2
kind: PgBouncer
metadata:
  name: pgbouncer-server
  namespace: demo
spec:
  version: "1.11.0"
  replicas: 1
  databases:
  - alias: "postgres"
    databaseName: "postgres"
    databaseRef:
      name: "quick-postgres"
  connectionPool:
    maxClientConnections: 20
    reservePoolSize: 5
    adminUsers:
    - admin
    - admin1
  userListSecretRef:
    name: db-user-pass
  monitor:
    agent: prometheus.io/operator
    prometheus:
      serviceMonitor:
        labels:
          k8s-app: prometheus
        interval: 10s

Here,

  • monitor.agent: prometheus.io/operator indicates that we are going to monitor this server using Prometheus operator.

  • monitor.prometheus.namespace: monitoring specifies that KubeDB should create ServiceMonitor in monitoring namespace.

  • monitor.prometheus.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 PgBouncer object that we have shown above,

$ kubectl apply -f https://github.com/kubedb/docs/raw/v2020.11.12/docs/examples/pgbouncer/monitoring/coreos-prom-pgbouncer.yaml
pgbouncer.kubedb.com/pgbouncer-server configured

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

$ kubectl get pb -n demo pgbouncer-server
NAME               VERSION   STATUS    AGE
pgbouncer-server   1.11.0    Running   10s

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

$  kubectl get svc -n demo --selector="kubedb.com/name=pgbouncer-server"
NAME                     TYPE        CLUSTER-IP       EXTERNAL-IP   PORT(S)     AGE
pgbouncer-server         ClusterIP   10.104.83.201    <none>        5432/TCP    52s
pgbouncer-server-stats   ClusterIP   10.101.214.117   <none>        56790/TCP   50s

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

Let’s describe this stats service.

$ kubectl describe svc -n demo pgbouncer-server-stats
Name:              pgbouncer-server-stats
Namespace:         demo
Labels:            kubedb.com/kind=PgBouncer
                   kubedb.com/name=pgbouncer-server
                   kubedb.com/role=stats
Annotations:       monitoring.appscode.com/agent:prometheus.io/operator
Selector:          kubedb.com/kind=PgBouncer,kubedb.com/name=pgbouncer-server
Type:              ClusterIP
IP:                10.101.214.117
Port:              prom-http  56790/TCP
TargetPort:        prom-http/TCP
Endpoints:         172.17.0.7:56790
Session Affinity:  None

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

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

$ kubectl get servicemonitor -n monitoring
NAME                           AGE
kubedb-demo-pgbouncer-server   3m4s

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

$ kubectl get servicemonitor -n monitoring kubedb-demo-pgbouncer-server -o yaml
apiVersion: monitoring.coreos.com/v1
kind: ServiceMonitor
metadata:
  creationTimestamp: "2019-09-19T10:03:24Z"
  generation: 1
  labels:
    k8s-app: prometheus
    monitoring.appscode.com/service: pgbouncer-server-stats.demo
  name: kubedb-demo-pgbouncer-server
  namespace: monitoring
  ownerReferences:
  - apiVersion: v1
    blockOwnerDeletion: true
    kind: Service
    name: pgbouncer-server-stats
    uid: 749bc2ed-e14c-4a9e-9688-9d319af2b902
  resourceVersion: "41639"
  selfLink: /apis/monitoring.coreos.com/v1/namespaces/monitoring/servicemonitors/kubedb-demo-pgbouncer-server
  uid: 4a68d942-a003-4b47-a8cb-f20e526e9748
spec:
  endpoints:
  - honorLabels: true
    interval: 5s
    path: /metrics
    port: prom-http
  namespaceSelector:
    matchNames:
    - demo
  selector:
    matchLabels:
      kubedb.com/kind: PgBouncer
      kubedb.com/name: pgbouncer-server
      kubedb.com/role: stats

Notice that the ServiceMonitor has label k8s-app: prometheus that we had specified in PgBouncer crd.

Also notice that the ServiceMonitor has selector which match the labels we have seen in the pgbouncer-server-stats service. It also, target the prom-http 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-0   3/3     Running   1          35m

Prometheus server is listening to port 9090 of 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-0 pod,

$ kubectl port-forward -n monitoring 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/targets in your browser. You should see prom-http endpoint of pgbouncer-server-stats service as one of the targets.

  Prometheus Target

Check the endpoint and service labels which verify 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 beautiful dashboard with collected metrics.

Cleaning up

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

# cleanup prometheus resources
kubectl delete -n monitoring prometheus prometheus
kubectl delete -n monitoring clusterrolebinding prometheus
kubectl delete -n monitoring clusterrole prometheus
kubectl delete -n monitoring serviceaccount prometheus
kubectl delete -n monitoring service prometheus-operated

# delete namespace
kubectl delete ns monitoring

Next Steps