:Use Alibaba Cloud Managed Service for Prometheus to monitor Go applications

Demo

You can also use a demo project to learn how to monitor a Go application by using Managed Service for Prometheus. For more information about the demo project, visit GitHub.

Procedure

The following figure describes how to use Managed Service for Prometheus to monitor a Go application.

Step 1: Instrument a Go application

To instrument a Go application to expose data, perform the following steps:

1. Import the monitoring package to the Go application.

   import (
       "fmt"
       "github.com/prometheus/client_golang/prometheus/promhttp"
       "net/http"
       "strconv"
   )

2. Associate the HTTP endpoint of Managed Service for Prometheus with promhttp.Handler().

   http.Handle(path, promhttp.Handler()) // Initialize an HTTP handler. 

Step 2: Upload the Go application

To build an image for the instrumented Go application and upload the image to an image repository of Container Registry, perform the following steps:

1. Run the following command to recompile a module:

   go build

2. Run the following command to build an image:

   docker build -t <Name of the local temporary Docker image>:<Version number of the local temporary Docker image> . --no-cache

   Example:

   docker build -t prometheus-go-demo:v0 . --no-cache

3. Run the following command to tag the image:

   sudo docker tag <Name of the local temporary Docker image>:<Version number of the local temporary Docker image> <Domain name of the image repository>/<Namespace>/<Image name>:<Image version number>

   Example:

   sudo docker tag prometheus-go-demo:v0 registry.cn-hangzhou.aliyuncs.com/testnamespace/prometheus-go-demo:v0

4. Run the following command to upload the image to the image repository:

   sudo docker push <Domain name of the image repository>/<Namespace>/<Image name>:<Image version number>

   Example:

   sudo docker push registry.cn-hangzhou.aliyuncs.com/testnamespace/prometheus-go-demo:v0

   You can view the information about the uploaded application image on the Tags page of the Container Registry console.

Step 3: Deploy the Go application

To deploy the Go application to an ACK cluster, perform the following steps:

1. Log on to the ACK console.
2. In the left-side navigation pane, click Clusters.
3. On the Clusters page, find the cluster to which you want to deploy the application and click Applications in the Actions column.
4. Create a container group.
   1. In the left-side navigation pane, choose Workloads > Deployments.
   2. On the Deployments page, click Create from YAML in the upper-right corner.
   3. On the Create page, enter the following code in the Template code editor and click Create:

      apiVersion: apps/v1 # for versions before 1.8.0 use apps/v1beta1
      kind: Deployment
      metadata:
        name: prometheus-go-demo
        labels:
          app: go-exporter
      spec:
        replicas: 2
        selector:
          matchLabels:
            app: go-exporter
        template:
          metadata:
            labels:
              app: go-exporter
          spec:
            containers:
            - name: prometheus-go-demo
              imagePullPolicy: Always
              image: <Domain name of the image repository>/<Namespace>/<Image name>:<Image version number>
              ports:
              - containerPort: 8077
                name: arms-go-demo

      Sample code:

      apiVersion: apps/v1 # for versions before 1.8.0 use apps/v1beta1
      kind: Deployment
      metadata:
        name: prometheus-go-demo
        labels:
          app: go-exporter
      spec:
        replicas: 2
        selector:
          matchLabels:
            app: go-exporter
        template:
          metadata:
            labels:
              app: go-exporter
          spec:
            containers:
            - name: prometheus-go-demo
              imagePullPolicy: Always
              image: registry.cn-hangzhou.aliyuncs.com/fuling/prometheus-go-demo:v0
              ports:
              - containerPort: 8077
                name: arms-go-demo

   The newly created container group is displayed on the Deployments page.
5. Create a Service.
   1. In the left-side navigation pane, choose Network > Services.
   2. On the Services page, click Create Resources in YAML.
   3. On the Create page, enter the following code in the Template code editor and click Create:

      apiVersion: v1
      kind: Service
      metadata:
        labels:
          app: prometheus-go-demo
        name: prometheus-go-demo
      spec:
        ports:
        - name: arms-go-demo
          port: 8077
          protocol: TCP
          targetPort: 8077
        type: NodePort
        selector:
          app: prometheus-go-demo

   The newly created Service is displayed on the Services page.

Step 4: Configure a service discovery task

To configure a service discovery task of Managed Service for Prometheus to receive data from the Go application, perform the following steps:

1. Log on to the Prometheus console.
2. In the top navigation bar of the Prometheus Monitoring page, select the region where the monitored ACK cluster resides. Then, click the name of the Prometheus instance that monitors the ACK cluster.
3. In the left-side navigation pane, click Service Discovery. Then, click the Configure tab.
4. On the Service Discovery tab, click the ServiceMonitor tab. Then, click Add ServiceMonitor.
5. In the Add ServiceMonitor dialog box, enter the following code and click OK:

   apiVersion: monitoring.coreos.com/v1
   kind: ServiceMonitor
   metadata:
     # Enter a unique name.
     name: prometheus-go-demo
     # Enter a namespace.
     namespace: default
   spec:
     endpoints:
     - interval: 30s
       # Enter the value of the Name field of the Port parameter of the Prometheus exporter.
       port: arms-go-demo
       # Enter the value of the Path field of the Prometheus exporter.
       path: /metrics
     namespaceSelector:
       any: true
       # The namespace of the demo.
     selector:
       matchLabels:
         app: prometheus-go-demo

   The configured service discovery task is displayed on the ServiceMonitor tab.

Step 5: Configure a Grafana dashboard

To configure a Grafana dashboard to display data, perform the following steps:

1. Go to the homepage of Grafana dashboards.
2. In the left-side navigation pane, click , enter choose Import.
3. On the Import page, enter 6671 (the ID of the Grafana template provided by Prometheus for Go applications) in the Import via grafna.com field and click Load next to the field.
   
4. On the Import page, perform the following operations and click Import:
   
   1. Enter a dashboard name in the Name field.
   2. Select your ACK cluster from the Folder drop-down list.
   3. Select your ACK cluster from the prometheus-apl drop-down list.
   The following figure shows the configured Grafana dashboard.

Step 6: Create an alert rule

1. Log on to the Prometheus console.
2. In the top navigation bar of the Prometheus Monitoring page, select the region where the monitored Kubernetes cluster resides. Then, click the name of the Kubernetes cluster.
3. In the left-side navigation pane, click Alarm configuration.
4. On the Alarm configuration page, click Create Alert in the upper-right corner.
5. In the Create Alert panel, set the parameters.
   1. Optional:Select a template from the Alarm template drop-down list.
   2. Enter a rule name in the Rule Name field. Example: Alert for inbound traffic.
   3. Enter a PromQL statement as the expression in the Alarm expression field. Example: (sum(rate(kube_state_metrics_list_total{job="kube-state-metrics",result="error"}[5m])) / sum(rate(kube_state_metrics_list_total{job="kube-state-metrics"}[5m]))) > 0.01.
      Important If a PromQL statement contains a dollar sign ($), an error is returned. You must delete the equal sign (=) and the parameters on both sides of the equal sign (=) from the statement that contains the dollar sign ($). For example, change sum (rate (container_network_receive_bytes_total{instance=~"^$HostIp.*"}[1m])) to sum (rate (container_network_receive_bytes_total[1m])).
   4. Enter a number N in the duration field. After the alert rule is created, an alert notification is sent only when the alert condition is met for N consecutive minutes. For example, you can enter 1. In this case, an alert notification is sent only when the alert condition is met for one consecutive minute.
      Note The alert condition refers to the condition specified by the PromQL statement. By default, Prometheus collects data at intervals of 15 seconds. If less than 4N consecutively collected data records meet the alert condition, no alert notification is sent. The threshold 4N is calculated by using the following formula: N × 60/15 = 4N. In this example, N is set to 1. Therefore, an alert notification is sent only when four consecutively collected data records meet the alert condition. To ensure that an alert notification can be sent each time a collected data record meets the alert condition, set N to 0.
   5. Enter the notification content in the Alarm message field.
   6. Optional:In the Labels section of Advanced Configuration, click Create Tag to add one or more tags to the alert rule. The specified tags can be used as options for a notification rule.
   7. Optional:In the Annotations section of Advanced Configuration, click Create Annotation. Then, enter message in the Key field and {{variable name}} alert message in the Value field. The specified annotation is in the format of message:{{variable name}} alert message. Example: message:{{$labels.pod_name}} restart.

      You can customize a variable name or select an existing tag as the variable name. The following content describes the existing tags:

      • The tags that are carried in the metrics of an alert rule expression.
      • The tags that are created when you create an alert rule. For more information, see Create an alert rule.
      • The default tags provided by ARMS. The following table describes the default tags.

        Tag	Description
        alertname	The name of the alert. The format is <Alert name>_<Cluster name>.
        _aliyun_arms_alert_level	The level of the alert.
        _aliyun_arms_alert_type	The type of the alert.
        _aliyun_arms_alert_rule_id	The ID of the alert rule.
        _aliyun_arms_region_id	The ID of the region.
        _aliyun_arms_userid	The ID of the user.
        _aliyun_arms_involvedObject_type	The subtype of the associated object, for example, ManagedKubernetes or ServerlessKubernetes.
        _aliyun_arms_involvedObject_kind	The type of the associated object, for example, app or cluster.
        _aliyun_arms_involvedObject_id	The ID of the associated object.
        _aliyun_arms_involvedObject_name	The name of the associated object.

   8. Click OK.
   After you create the alert rule, the Alarm configuration page displays the rule, as shown in the following figure.