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Monitoring MSSQLServer 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 MSSQLServer deployed with KubeDB.

Before You Begin

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.
Now, install KubeDB cli on your workstation and KubeDB operator in your cluster following the steps here. Make sure install with helm command including --set global.featureGates.MSSQLServer=true to ensure MSSQLServer CRD installation.
To configure TLS/SSL in MSSQLServer, KubeDB uses cert-manager to issue certificates. So first you have to make sure that the cluster has cert-manager installed. To install cert-manager in your cluster following steps here.
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

$ kubectl create ns demo
namespace/demo created
```
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.

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

Find out required labels for ServiceMonitor

We need to know the labels used to select ServiceMonitor by Prometheus Operator. We are going to provide these labels in spec.monitor.prometheus.labels field of MSSQLServer CR 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   v2.54.1   1         1       True         True        16d

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-kube-prometheus-prometheus in monitoring namespace.

$ kubectl get prometheus -n monitoring prometheus-kube-prometheus-prometheus -oyaml

apiVersion: monitoring.coreos.com/v1
kind: Prometheus
metadata:
  annotations:
    meta.helm.sh/release-name: prometheus
    meta.helm.sh/release-namespace: monitoring
  creationTimestamp: "2024-10-14T10:14:36Z"
  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: 65.2.0
    chart: kube-prometheus-stack-65.2.0
    heritage: Helm
    release: prometheus
  name: prometheus-kube-prometheus-prometheus
  namespace: monitoring
  resourceVersion: "1004097"
  uid: b7879d3e-e4bb-4425-8d78-f917561d95f7
spec:
  alerting:
    alertmanagers:
      - apiVersion: v2
        name: prometheus-kube-prometheus-alertmanager
        namespace: monitoring
        pathPrefix: /
        port: http-web
  automountServiceAccountToken: true
  enableAdminAPI: false
  evaluationInterval: 30s
  externalUrl: http://prometheus-kube-prometheus-prometheus.monitoring:9090
  hostNetwork: false
  image: quay.io/prometheus/prometheus:v2.54.1
  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: v2.54.1
  walCompression: true
status:
  availableReplicas: 1
  conditions:
    - lastTransitionTime: "2024-10-31T07:38:36Z"
      message: ""
      observedGeneration: 1
      reason: ""
      status: "True"
      type: Available
    - lastTransitionTime: "2024-10-31T07:38:36Z"
      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 CR. So, we are going to use this label in spec.monitor.prometheus.labels field of MSSQLServer CR.

Deploy MSSQLServer with Monitoring Enabled

First, an issuer needs to be created, even if TLS is not enabled for SQL Server. The issuer will be used to configure the TLS-enabled Wal-G proxy server, which is required for the SQL Server backup and restore operations.

Create Issuer/ClusterIssuer

Now, we are going to create an example Issuer that will be used throughout the duration of this tutorial. Alternatively, you can follow this cert-manager tutorial to create your own Issuer. By following the below steps, we are going to create our desired issuer,

Start off by generating our ca-certificates using openssl,

openssl req -x509 -nodes -days 365 -newkey rsa:2048 -keyout ./ca.key -out ./ca.crt -subj "/CN=MSSQLServer/O=kubedb"

Create a secret using the certificate files we have just generated,

$ kubectl create secret tls mssqlserver-ca --cert=ca.crt  --key=ca.key --namespace=demo 
secret/mssqlserver-ca created

Now, we are going to create an Issuer using the mssqlserver-ca secret that contains the ca-certificate we have just created. Below is the YAML of the Issuer CR that we are going to create,

apiVersion: cert-manager.io/v1
kind: Issuer
metadata:
 name: mssqlserver-ca-issuer
 namespace: demo
spec:
 ca:
   secretName: mssqlserver-ca

Let’s create the Issuer CR we have shown above,

$ kubectl create -f https://github.com/kubedb/docs/raw/v2024.9.30/docs/examples/mssqlserver/ag-cluster/mssqlserver-ca-issuer.yaml
issuer.cert-manager.io/mssqlserver-ca-issuer created

Now, let’s deploy an MSSQLServer with monitoring enabled. Below is the MSSQLServer object that we are going to create.

apiVersion: kubedb.com/v1alpha2
kind: MSSQLServer
metadata:
  name: mssql-monitoring
  namespace: demo
spec:
  version: "2022-cu12"
  replicas: 1
  tls:
    issuerRef:
      name: mssqlserver-ca-issuer
      kind: Issuer
      apiGroup: "cert-manager.io"
    clientTLS: false
  monitor:
    agent: prometheus.io/operator
    prometheus:
      exporter:
        port: 9399
        resources:
          limits:
            memory: 512Mi
          requests:
            cpu: 200m
            memory: 256Mi
        securityContext:
          allowPrivilegeEscalation: false
          capabilities:
            drop:
              - ALL
          runAsGroup: 10001
          runAsNonRoot: true
          runAsUser: 10001
          seccompProfile:
            type: RuntimeDefault
      serviceMonitor:
        interval: 10s
        labels:
          release: prometheus
  storageType: Durable
  storage:
    storageClassName: standard
    accessModes:
      - ReadWriteOnce
    resources:
      requests:
        storage: 1Gi
  deletionPolicy: WipeOut

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 MSSQLServer object that we have shown above,

$ kubectl create -f https://github.com/kubedb/docs/raw/v2024.9.30/docs/examples/mssqlserver/monitoring/mssql-monitoring.yaml
mssqlserverql.kubedb.com/mssql-monitoring created

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

$ kubectl get ms -n demo mssql-monitoring
NAME               VERSION     STATUS   AGE
mssql-monitoring   2022-cu12   Ready    108m

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

$ kubectl get svc -n demo --selector="app.kubernetes.io/instance=mssql-monitoring"
NAME                     TYPE        CLUSTER-IP      EXTERNAL-IP   PORT(S)    AGE
mssql-monitoring         ClusterIP   10.96.225.130   <none>        1433/TCP   108m
mssql-monitoring-pods    ClusterIP   None            <none>        1433/TCP   108m
mssql-monitoring-stats   ClusterIP   10.96.147.93    <none>        9399/TCP   108m

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

Let’s describe this stats service.

$ kubectl describe svc -n demo mssql-monitoring-stats

Name:              mssql-monitoring-stats
Namespace:         demo
Labels:            app.kubernetes.io/component=database
  app.kubernetes.io/instance=mssql-monitoring
  app.kubernetes.io/managed-by=kubedb.com
  app.kubernetes.io/name=mssqlservers.kubedb.com
  kubedb.com/role=stats
Annotations:       monitoring.appscode.com/agent: prometheus.io/operator
Selector:          app.kubernetes.io/instance=mssql-monitoring,app.kubernetes.io/managed-by=kubedb.com,app.kubernetes.io/name=mssqlservers.kubedb.com
Type:              ClusterIP
IP Family Policy:  SingleStack
IP Families:       IPv4
IP:                10.96.147.93
IPs:               10.96.147.93
Port:              metrics  9399/TCP
TargetPort:        metrics/TCP
Endpoints:         10.244.0.47:9399
Session Affinity:  None
Events:            <none>

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

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

$ kubectl get servicemonitor -n demo
NAME                     AGE
mssql-monitoring-stats   110m

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

$ kubectl get servicemonitor -n demo mssql-monitoring-stats -o yaml

apiVersion: monitoring.coreos.com/v1
kind: ServiceMonitor
metadata:
  creationTimestamp: "2024-10-31T07:38:36Z"
  generation: 1
  labels:
    app.kubernetes.io/component: database
    app.kubernetes.io/instance: mssql-monitoring
    app.kubernetes.io/managed-by: kubedb.com
    app.kubernetes.io/name: mssqlservers.kubedb.com
    release: prometheus
  name: mssql-monitoring-stats
  namespace: demo
  ownerReferences:
    - apiVersion: v1
      blockOwnerDeletion: true
      controller: true
      kind: Service
      name: mssql-monitoring-stats
      uid: 99193679-301b-41fd-aae5-a732b3070d19
  resourceVersion: "1004080"
  uid: 87635ad4-dfb2-4544-89af-e48b40783205
spec:
  endpoints:
    - honorLabels: true
      interval: 10s
      path: /metrics
      port: metrics
  namespaceSelector:
    matchNames:
      - demo
  selector:
    matchLabels:
      app.kubernetes.io/component: database
      app.kubernetes.io/instance: mssql-monitoring
      app.kubernetes.io/managed-by: kubedb.com
      app.kubernetes.io/name: mssqlservers.kubedb.com
      kubedb.com/role: stats

Notice that the ServiceMonitor has label release: prometheus that we had specified in MSSQLServer CR.

Also notice that the ServiceMonitor has selector which match the labels we have seen in the mssql-monitoring-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-kube-prometheus-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   1                16d

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-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 mssql-monitoring-stats service as one of the targets.

Prometheus Target

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 beautiful dashboards with collected metrics.

Grafana Dashboards

There are three dashboards to monitor Microsoft SQL Server Databases managed by KubeDB.

KubeDB / MSSQLServer / Summary: Shows overall summary of Microsoft SQL Server instance.
KubeDB / MSSQLServer / Pod: Shows individual pod-level information.
KubeDB / MSSQLServer / Database: Shows Microsoft SQL Server internal metrics for an instance.

Note: These dashboards are developed in Grafana version 7.5.5

To use KubeDB Grafana Dashboards to monitor Microsoft SQL Server Databases managed by KubeDB, Check out mssqlserver-dashboards

Cleaning up

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

kubectl delete -n demo ms/mssql-monitoring
kubectl delete ns demo

helm uninstall prometheus -n monitoring
kubectl delete ns monitoring

Next Steps

Learn about backup and restore SQL Server using KubeStash.
Want to hack on KubeDB? Check our contribution guidelines.

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