Connecting PostgreSQL Exporter

Application Scenario

When using PostgreSQL, you need to monitor their status and locate their faults in a timely manner. The Prometheus monitoring function monitors PostgreSQL running using Exporter in the CCE container scenario. This section describes how to deploy PostgreSQL Exporter and implement alarm access.

Prerequisites

A CCE cluster has been created and PostgreSQL has been installed.
Your service has been connected for Prometheus monitoring and a CCE cluster has also been connected. For details, see Prometheus Instance for CCE.
You have uploaded the postgres_exporter image to SoftWare Repository for Container (SWR). For details, see Uploading an Image Through a Container Engine Client.

Deploying PostgreSQL Exporter

Log in to the CCE console.
Click the connected cluster. The cluster management page is displayed.

Perform the following operations to deploy Exporter:

Use Secret to manage PostgreSQL passwords.
In the navigation pane, choose Workloads. In the upper right corner, click Create from YAML to configure a YAML file. In the YAML file, use Kubernetes Secret to manage and encrypt passwords. When starting PostgreSQL Exporter, the secret key can be directly used but the corresponding password needs to be changed as required.

YAML configuration example:
```
apiVersion: v1
kind: Secret
metadata:
    name: postgres-test
type: Opaque
stringData:
    username: postgres
    password: you-guess # PostgreSQL password.
```

Deploy PostgreSQL Exporter.

In the navigation pane, choose Workloads. In the upper right corner, click Create from YAML to deploy Exporter.

YAML configuration example (Change the parameters if needed):

apiVersion: apps/v1
kind: Deployment
metadata:
  name: postgres-test # Change the name based on requirements. You are advised to add the PostgreSQL instance information.
  namespace: default # Must be the same as the namespace of the PostgreSQL service.
  labels:
    app: postgres
    app.kubernetes.io/name: postgresql
spec:
  replicas: 1
  selector:
    matchLabels:
      app: postgres
      app.kubernetes.io/name: postgresql
  template:
    metadata:
      labels:
        app: postgres
        app.kubernetes.io/name: postgresql
    spec:
      containers:
      - name: postgres-exporter
        image: swr.cn-north-4.myhuaweicloud.com/aom-exporter/postgres-exporter:v0.8.0 # postgres-exporter image uploaded to SWR.
        args:
          - "--web.listen-address=:9187" # Enabled port of Exporter.
          - "--log.level=debug" # Log level.
        env:
          - name: DATA_SOURCE_USER
            valueFrom:
              secretKeyRef:
                name: postgres-test # Secret name specified in the previous step.
                key: username  # Secret key specified in the previous step.
          - name: DATA_SOURCE_PASS 
            valueFrom:
              secretKeyRef:
                name: postgres-test # Secret name specified in the previous step.
                key: password  # Secret key specified in the previous step.
          - name: DATA_SOURCE_URI
            value: "x.x.x.x:5432/postgres?sslmode=disable"  # Connection information.
        ports:
        - name: http-metrics
          containerPort: 9187

Obtain metrics.

The running time of the Postgres instance cannot be obtained by running the curl http://exporter:9187/metrics command. To obtain this metric, customize a queries.yaml file.

Create a configuration that contains queries.yaml.
Mount the configuration as a volume to a directory of Exporter.

Use the configuration through extend.query-path. The following shows Secret and Deployment:

# The following shows the queries.yaml file that contains custom metrics:
---
apiVersion: v1
kind: ConfigMap
metadata:
  name: postgres-test-configmap
  namespace: default
data:
  queries.yaml: |
    pg_postmaster:
      query: "SELECT pg_postmaster_start_time as start_time_seconds from pg_postmaster_start_time()"
      master: true
      metrics:
        - start_time_seconds:
            usage: "GAUGE"
            description: "Time at which postmaster started"

# The following shows the mounted Secret and ConfigMap, and defines Exporter deployment parameters (such as the image):
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: postgres-test
  namespace: default
  labels:
    app: postgres
    app.kubernetes.io/name: postgresql
spec:
  replicas: 1
  selector:
    matchLabels:
      app: postgres
      app.kubernetes.io/name: postgresql
  template:
    metadata:
      labels:
        app: postgres
        app.kubernetes.io/name: postgresql
    spec:
      containers:
        - name: postgres-exporter
          image: wrouesnel/postgres_exporter:latest
          args:
            - "--web.listen-address=:9187"
            - "--extend.query-path=/etc/config/queries.yaml"
            - "--log.level=debug"
          env:
            - name: DATA_SOURCE_USER
              valueFrom:
                secretKeyRef:
                  name: postgres-test-secret
                  key: username
            - name: DATA_SOURCE_PASS
              valueFrom:
                secretKeyRef:
                  name: postgres-test-secret
                  key: password
            - name: DATA_SOURCE_URI
              value: "x.x.x.x:5432/postgres?sslmode=disable"
          ports:
            - name: http-metrics
              containerPort: 9187
          volumeMounts:
            - name: config-volume
              mountPath: /etc/config
      volumes:
        - name: config-volume
          configMap:
            name: postgres-test-configmap
---
apiVersion: v1
kind: Service
metadata:
  name: postgres
spec:
  type: NodePort
  selector:
    app: postgres
    app.kubernetes.io/name: postgresql
  ports:
    - protocol: TCP
      nodePort: 30433
      port: 9187
      targetPort: 9187

Access the following address:
http://{Public IP address of any node in the cluster}:30433/metrics. You can then use the custom queries.yaml file to query the Postgres instance startup time.
Figure 1 Accessing a cluster node

Adding a Collection Task

Add PodMonitor to configure a collection rule for monitoring the service data of applications deployed in the CCE cluster.

In the following example, metrics are collected every 30s. Therefore, you can check the reported metrics on the AOM page about 30s later.

apiVersion: monitoring.coreos.com/v1
kind: PodMonitor
metadata:
  name: postgres-exporter
  namespace: default
spec:
  namespaceSelector:
    matchNames:
      - default # Namespace where Exporter is located.
  podMetricsEndpoints:
  - interval: 30s
    path: /metrics
    port: http-metrics
  selector:
    matchLabels:
      app: postgres

Verifying that Metrics Can Be Reported to AOM

Log in to the AOM 2.0 console.
In the navigation pane on the left, choose Prometheus Monitoring > Instances.
Click the Prometheus instance connected to the CCE cluster. The instance details page is displayed.
On the Metrics tab page of the Service Discovery page, select your target cluster.
Select job {namespace}/postgres-exporter to query metrics starting with pg.

Setting a Dashboard and Alarm Rule on AOM

By setting a dashboard, you can monitor CCE cluster data on the same screen. By setting an alarm rule, you can detect cluster faults and implement warning in a timely manner.

Setting a dashboard
1. Log in to the AOM 2.0 console.
2. In the navigation pane, choose Dashboard. On the displayed page, click Add Dashboard to add a dashboard. For details, see Creating a Dashboard.
3. On the Dashboard page, select a Prometheus instance for CCE and click Add Graph. For details, see Adding a Graph to a Dashboard.
Setting an alarm rule
1. Log in to the AOM 2.0 console.
2. In the navigation pane, choose Alarm Management > Alarm Rules.
3. Click Create Alarm Rule to set an alarm rule. For details, see Creating a Metric Alarm Rule.