Apache Flink

This document describes how to configure your Google Kubernetes Engine deployment so that you can use Google Cloud Managed Service for Prometheus to collect metrics from the Flink exporter. This document shows you how to do the following:

• Set up the Flink exporter to report metrics.
• Configure a PodMonitoring resource for Managed Service for Prometheus to collect the exported metrics.
• Access a dashboard in Cloud Monitoring to view the metrics.
• Configure alerting rules to monitor the metrics.

These instructions apply only if you are using managed collection with Managed Service for Prometheus. If you are using self-deployed collection, then see the Flink documentation for installation information.

These instructions are provided as an example and are expected to work in most Kubernetes environments. If you are having trouble installing an application or exporter due to restrictive security or organizational policies, then we recommend you consult open-source documentation for support.

For information about Flink, see Apache Flink.

Prerequisites

To collect metrics from the Flink exporter by using Managed Service for Prometheus and managed collection, your deployment must meet the following requirements:

• Your cluster must be running Google Kubernetes Engine version 1.21.4-gke.300 or later.
• You must be running Managed Service for Prometheus with managed collection enabled. For more information, see Get started with managed collection.

• To use dashboards available in Cloud Monitoring for the Flink integration, you must use flink version 1.17 or later.

  For more information about available dashboards, see View dashboards.

If you deployed Flink with the official getting started manifests, add this new option to the ConfigMap:

  apiVersion: v1
  kind: ConfigMap
  metadata:
    name: flink-config
    labels:
      app: flink
  data:
    flink-conf.yaml: |+
      ...
  +   metrics.reporter.prom.factory.class: org.apache.flink.metrics.prometheus.PrometheusReporterFactory
  

If you deployed Flink with the official operator, add this new option to the FlinkDeployment's spec.flinkConfiguration field:

  apiVersion: flink.apache.org/v1beta1
  kind: FlinkDeployment
  metadata:
    name: basic-example
  spec:
    image: flink:1.17
    flinkVersion: v1_17
    flinkConfiguration:
      taskmanager.numberOfTaskSlots: "2"
  +   metrics.reporter.prom.factory.class: org.apache.flink.metrics.prometheus.PrometheusReporterFactory
  

Alternatively, you can specify the Prometheus reporter as a default option within the Flink operator configuration.

To verify that the Flink exporter is emitting metrics on the expected endpoints, do the following:

1. Set up port forwarding by using the following command:

   kubectl -n NAMESPACE_NAME port-forward POD_NAME 9249
   

2. Access the endpoint localhost:9249/metrics by using the browser or the curl utility in another terminal session.

Define a PodMonitoring resource

For target discovery, the Managed Service for Prometheus Operator requires a PodMonitoring resource that corresponds to the Flink exporter in the same namespace.

You can use the following PodMonitoring configuration:

# Copyright 2024 Google LLC
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

apiVersion: monitoring.googleapis.com/v1
kind: PodMonitoring
metadata:
  name: flink
  labels:
    app.kubernetes.io/name: flink
    app.kubernetes.io/part-of: google-cloud-managed-prometheus
spec:
  endpoints:
  - port: 9249
    scheme: http
    interval: 30s
    path: /metrics
  selector:
    matchLabels:
      app.kubernetes.io/name: flink

To apply configuration changes from a local file, run the following command:

kubectl apply -n NAMESPACE_NAME -f FILE_NAME

You can also use Terraform to manage your configurations.

Define rules and alerts

You can use the following Rules configuration to define alerts on your Flink metrics:

# Copyright 2024 Google LLC
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

apiVersion: monitoring.googleapis.com/v1
kind: Rules
metadata:
  name: flink-rules
  labels:
    app.kubernetes.io/component: rules
    app.kubernetes.io/name: flink-rules
    app.kubernetes.io/part-of: google-cloud-managed-prometheus
spec:
  groups:
  - name: flink
    interval: 30s
    rules:
    - alert: FlinkHighJVMMemoryNonHeapUsage
      annotations:
        description: |-
          Flink high jvm memory non-heap usage
            VALUE = {{ $value }}
            LABELS: {{ $labels }}
        summary: Flink high jvm memory non-heap usage (instance {{ $labels.instance }})
      expr: (flink_jobmanager_Status_JVM_Memory_NonHeap_Used/flink_jobmanager_Status_JVM_Memory_NonHeap_Max) >= 0.9
      for: 5m
      labels:
        severity: critical
    - alert: FlinkHighJVMMemoryHeapUsage
      annotations:
        description: |-
          Flink high jvm memory heap usage
            VALUE = {{ $value }}
            LABELS: {{ $labels }}
        summary: Flink high jvm memory heap usage (instance {{ $labels.instance }})
      expr: (flink_jobmanager_Status_JVM_Memory_Heap_Used/flink_jobmanager_Status_JVM_Memory_Heap_Max) >= 0.9
      for: 5m
      labels:
        severity: warning

To apply configuration changes from a local file, run the following command:

kubectl apply -n NAMESPACE_NAME -f FILE_NAME

You can also use Terraform to manage your configurations.

For more information about applying rules to your cluster, see Managed rule evaluation and alerting.

Verify the configuration

You can use Metrics Explorer to verify that you correctly configured the Flink exporter. It might take one or two minutes for Cloud Monitoring to ingest your metrics.

To verify the metrics are ingested, do the following:

1. In the Google Cloud console, go to the leaderboard Metrics explorer page:

   Go to Metrics explorer

   If you use the search bar to find this page, then select the result whose subheading is Monitoring.

2. In the toolbar of the query-builder pane, select the button whose name is either code MQL or code PromQL.
3. Verify that PromQL is selected in the Language toggle. The language toggle is in the same toolbar that lets you format your query.
4. Enter and run the following query:
   

   up{job="flink", cluster="CLUSTER_NAME", namespace="NAMESPACE_NAME"}

View dashboards

The Cloud Monitoring integration includes "Prometheus" dashboards. Dashboards are automatically installed when you configure the integration. You can also view static previews of dashboards without installing the integration.

To view an installed dashboard, do the following:

1. In the Google Cloud console, go to the  Dashboards page:

   Go to Dashboards

   If you use the search bar to find this page, then select the result whose subheading is Monitoring.

2. Select the Dashboard List tab.
3. Choose the Integrations category.
4. Click the name of the dashboard you want to view.

To view a static preview of the dashboard, do the following:

1. In the Google Cloud console, go to the  Integrations page:

   Go to Integrations

   If you use the search bar to find this page, then select the result whose subheading is Monitoring.

2. Click the Kubernetes Engine deployment-platform filter.
3. Locate the Apache Flink integration and click View Details.
4. Select the Dashboards tab.

Troubleshooting

For information about troubleshooting metric ingestion problems, see Problems with collection from exporters in Troubleshooting ingestion-side problems.