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Monitor HAProxy using Prometheus

This tutorial will show you how to monitor Voyager managed HAProxy pods using builtin Prometheus scraper.

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, deploy Voyager operator following instructions here.

To keep things isolated, this tutorial uses a separate namespace called demo throughout this tutorial. Run the following command to prepare your cluster for this tutorial:

$ kubectl create namespace demo
namespace "demo" created

$ kubectl get ns
NAME          STATUS    AGE
default       Active    45m
demo          Active    10s
kube-public   Active    45m
kube-system   Active    45m

Note that the yaml files that are used in this tutorial, stored in docs/examples folder in GitHub repository voyagermesh/docs.

Create Ingress

We are going to use a nginx server as the backend. To deploy nginx server, run the following commands:

kubectl run nginx --image=nginx -n demo
kubectl expose deployment nginx --name=web --port=80 --target-port=80 -n demo

Now create Ingress ing.yaml

$ kubectl apply -f https://raw.githubusercontent.com/appscode/voyager/v2021.04.24-rc.0/docs/examples/monitoring/builtin-prometheus/ing.yaml
ingress "stats-ing" created

apiVersion: voyager.appscode.com/v1beta1
kind: Ingress
metadata:
  name: stats-ing
  namespace: demo
  annotations:
    ingress.appscode.com/type: 'NodePort'
    ingress.appscode.com/stats: 'true'
    ingress.appscode.com/monitoring-agent: 'prometheus.io/builtin'
spec:
  rules:
  - host: voyager.appscode.test
    http:
      paths:
      - path: /
        backend:
          serviceName: web
          servicePort: 80

Voyager operator watches for Ingress objects using Kubernetes api. When a Ingress object is created, Voyager operator will create a new HAProxy deployment and a NodePort Service with name voyager-{ingress-name}. Since ingress.appscode.com/stats annotation was configured, a stats service object is configured accordingly. Here,

Keys Value Default Description
ingress.appscode.com/stats bool "false" Required. If set, HAProxy stats will be exposed
ingress.appscode.com/monitoring-agent string Required. Indicates the monitoring agent used. Here built-in scraper in Prometheus is used to monitor the HAProxy pods. Voyager operator will configure the stats service in a way that the Prometheus server will automatically find out the service endpoint and scrape metrics from exporter.

You can verify it running the following commands:

$ kubectl get pods,svc -n demo
NAME                                    READY     STATUS    RESTARTS   AGE
po/nginx-8586cf59-r2m59                 1/1       Running   0          1m
po/voyager-stats-ing-5bf6b54949-5zs4x   2/2       Running   0          1m

NAME                          TYPE        CLUSTER-IP      EXTERNAL-IP   PORT(S)               AGE
svc/voyager-stats-ing         NodePort    10.111.51.103   <none>        80:31094/TCP          1m
svc/voyager-stats-ing-stats   ClusterIP   10.97.119.249   <none>        56789/TCP,56790/TCP   1m
svc/web                       ClusterIP   10.98.249.140   <none>        80/TCP                1m

$ kubectl get svc -n demo voyager-stats-ing-stats -o yaml

apiVersion: v1
kind: Service
metadata:
  annotations:
    ingress.appscode.com/origin-api-schema: voyager.appscode.com/v1beta1
    ingress.appscode.com/origin-name: stats-ing
    monitoring.appscode.com/agent: prometheus.io/builtin
    prometheus.io/path: /voyager.appscode.com/v1beta1/namespaces/demo/ingresses/stats-ing/metrics
    prometheus.io/port: "56790"
    prometheus.io/scrape: "true"
  creationTimestamp: 2018-02-25T21:48:24Z
  labels:
    feature: stats
    origin: voyager
    origin-api-group: voyager.appscode.com
    origin-name: stats-ing
  name: voyager-stats-ing-stats
  namespace: demo
  resourceVersion: "317"
  selfLink: /api/v1/namespaces/demo/services/voyager-stats-ing-stats
  uid: 9ac02c7c-1a75-11e8-a133-080027640ad5
spec:
  clusterIP: 10.97.119.249
  ports:
  - name: stats
    port: 56789
    protocol: TCP
    targetPort: stats
  - name: http
    port: 56790
    protocol: TCP
    targetPort: http
  selector:
    origin: voyager
    origin-api-group: voyager.appscode.com
    origin-name: stats-ing
  sessionAffinity: None
  type: ClusterIP
status:
  loadBalancer: {}

We can see that the service contains these specific annotations. The Prometheus server will discover the exporter using these specifications.

prometheus.io/path: ...
prometheus.io/port: ...
prometheus.io/scrape: ...

Deploy and configure Prometheus Server

The Prometheus server is needed to configure so that it can discover endpoints of services. If a Prometheus server is already running in cluster and if it is configured in a way that it can discover service endpoints, no extra configuration will be needed. If there is no existing Prometheus server running, rest of this tutorial will create a Prometheus server with appropriate configuration.

The configuration file to Prometheus-Server will be provided by ConfigMap. The below config map will be created:

apiVersion: v1
kind: ConfigMap
metadata:
  name: prometheus-server-conf
  labels:
    name: prometheus-server-conf
  namespace: demo
data:
  prometheus.yml: |-
    global:
      scrape_interval: 5s
      evaluation_interval: 5s
    scrape_configs:
    - job_name: 'kubernetes-service-endpoints'

      kubernetes_sd_configs:
      - role: endpoints

      relabel_configs:
      - source_labels: [__meta_kubernetes_service_annotation_prometheus_io_scrape]
        action: keep
        regex: true
      - source_labels: [__meta_kubernetes_service_annotation_prometheus_io_scheme]
        action: replace
        target_label: __scheme__
        regex: (https?)
      - source_labels: [__meta_kubernetes_service_annotation_prometheus_io_path]
        action: replace
        target_label: __metrics_path__
        regex: (.+)
      - source_labels: [__address__, __meta_kubernetes_service_annotation_prometheus_io_port]
        action: replace
        target_label: __address__
        regex: ([^:]+)(?::\d+)?;(\d+)
        replacement: $1:$2
      - action: labelmap
        regex: __meta_kubernetes_service_label_(.+)
      - source_labels: [__meta_kubernetes_namespace]
        action: replace
        target_label: kubernetes_namespace
      - source_labels: [__meta_kubernetes_service_name]
        action: replace
        target_label: kubernetes_name

$ kubectl create -f https://raw.githubusercontent.com/appscode/voyager/v2021.04.24-rc.0/docs/examples/monitoring/builtin-prometheus/demo-1.yaml
configmap "prometheus-server-conf" created

Now, the below yaml is used to deploy Prometheus in kubernetes :

apiVersion: apps/v1
kind: Deployment
metadata:
  name: prometheus-server
  namespace: demo
spec:
  replicas: 1
  selector:
    matchLabels:
      app: prometheus-server
  template:
    metadata:
      labels:
        app: prometheus-server
    spec:
      containers:
        - name: prometheus
          image: prom/prometheus:v2.1.0
          args:
            - "--config.file=/etc/prometheus/prometheus.yml"
            - "--storage.tsdb.path=/prometheus/"
          ports:
            - containerPort: 9090
          volumeMounts:
            - name: prometheus-config-volume
              mountPath: /etc/prometheus/
            - name: prometheus-storage-volume
              mountPath: /prometheus/
      volumes:
        - name: prometheus-config-volume
          configMap:
            defaultMode: 420
            name: prometheus-server-conf
        - name: prometheus-storage-volume
          emptyDir: {}

Now, run the following command to deploy prometheus in kubernetes:

$ kubectl create -f https://raw.githubusercontent.com/appscode/voyager/v2021.04.24-rc.0/docs/examples/monitoring/builtin-prometheus/demo-2.yaml
clusterrole "prometheus-server" created
serviceaccount "prometheus-server" created
clusterrolebinding "prometheus-server" created
deployment "prometheus-server" created
service "prometheus-service" created

Prometheus Dashboard

Now to open prometheus dashboard on Browser:

$ kubectl get svc -n demo
NAME                 TYPE           CLUSTER-IP       EXTERNAL-IP   PORT(S)               AGE
voyager              ClusterIP      None             <none>        <none>                59m
mgo-mon-prometheus   ClusterIP      10.104.88.103    <none>        27017/TCP,56790/TCP   59m
prometheus-service   LoadBalancer   10.103.201.246   <pending>     9090:30901/TCP        8s


$ minikube ip
192.168.99.100

$ minikube service prometheus-service -n demo --url
http://192.168.99.100:30901

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://192.168.99.100:30901.

Now, if you go the Prometheus Dashboard, you should see that the HAProxy pod as one of the targets.

prometheus-builtin

Cleaning up

To cleanup the Kubernetes resources created by this tutorial, run:

$ kubectl delete ns demo
namespace "demo" deleted

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