In practical scenarios, the number of concurrent pod requests is commonly used to evaluate a Service. Knative collects request-related metrics by using the queue-proxy container. This topic describes how to use Application Real-Time Monitoring Service (ARMS) Prometheus to collect pod request-related metrics from a Knative Service.

Step 1: Install the Prometheus Monitoring component

  1. Log on to the ACK console.
  2. In the left-side navigation pane, choose Marketplace > App Catalog.
  3. On the App Catalog page, click the Alibaba Cloud Apps tab. Then, find and click ack-arms-prometheus.
  4. On the App Catalog - ack-arms-prometheus page, click the Parameters tab.
  5. In the Deploy section of the App Catalog - ack-arms-prometheus page, select the cluster for which you want to enable ARMS Prometheus, and click Create.
    Note By default, Namespace and Release Name are set to arms-prom.

Step 2: Set collection job rules for the queue-proxy container

  1. Log on to the ARMS console.
  2. In the left-side navigation pane, click Prometheus Monitoring.
  3. On the Prometheus Monitoring page, click Settings in the Actions column.
  4. Click the Prometheus Settings tab, add the following content to the Prometheus.yaml file, and click Save. 
    global:  
  scrape_interval: 30s
  scrape_timeout: 10s
  evaluation_interval: 30s
scrape_configs:
- job_name: queue-proxy
  scrape_interval: 3s
  scrape_timeout: 3s
  kubernetes_sd_configs:
  - role: pod
  relabel_configs:
  # Rename metadata labels to be reader friendly
  - source_labels: [__meta_kubernetes_pod_label_serving_knative_dev_revision, __meta_kubernetes_pod_container_port_name]
    action: keep
    regex: .+;http-autometric
  - source_labels: [__meta_kubernetes_namespace]
    target_label: namespace
  - source_labels: [__meta_kubernetes_pod_name]
    target_label: pod
  - source_labels: [__meta_kubernetes_service_name]
    target_label: service
  5. Click the Metrics tab to view the metrics related to the queue-proxy.
    Metrics

Step 3: Query the number of concurrent pod requests

  1. In the left-side navigation pane of the cluster configuration page, click Dashboards.
  2. On the Dashboards page, click Prometheus in the Name column.
  3. On the left side of the Prometheus page, click the Explore icon. explore
  4. In the Metrics drop-down list, select queue to view metrics related to queue-proxy.
    The queue_requests_per_second metric is collected in this example. metrics
    You can also query the number of concurrent pod requests per second by specifying the namespace, revision, and pod name. The following code block is an example: 
    queue_requests_per_second{destination_configuration="helloworld-go",destination_namespace="default",destination_pod="helloworld-go-ttf52-deployment-5778d86bd6-dnxw2"}
    Number of concurrent pod requests