Using logging and monitoring

This page explains how to use Cloud Logging and Cloud Monitoring as well as Prometheus and Grafana for logging and monitoring. For a summary of the configuration options available, see Logging and monitoring overview.

Using Cloud Logging and Cloud Monitoring

The following sections explain how to use Logging and Monitoring with GKE on-prem clusters.

Monitored resources

Monitored resources are how Google represents resources such as clusters, nodes, Pods, and containers. To learn more, refer to Cloud Monitoring's Monitored resource types documentation.

To query for logs and metrics, you'll need to know at least these resource labels:

• project_id: Project ID for the project associated with the GKE on-prem cluster.

• location: A Google Cloud region where you want to store Logging logs and Monitoring metrics. It's a good idea to choose a region that is near your on-premises data center. You provided this value during installation in the stackdriver.clusterlocation field of your GKE on-prem configuration file.

• cluster_name: Cluster name that you chose when you created the cluster.

  You can retrieve the cluster_name value for either the admin or the user cluster by inspecting the Stackdriver custom resource:

    kubectl -n kube-system get stackdrivers stackdriver -o yaml | grep 'clusterName:'

Accessing log data

You can access logs using the Logs Explorer in Google Cloud console. For example, to access a container's logs:

1. Open the Logs Explorer in Google Cloud console for your project.
2. Find logs for a container by:
   1. Clicking on the top-left log catalog drop-down box and selecting Kubernetes Container.
   2. Selecting the cluster name, then the namespace, and then a container from the hierarchy.

Creating dashboards to monitor cluster health

GKE on-prem clusters are, by default, configured to monitor system and container metrics. After you create a cluster (admin or user), a best practice is to create the following dashboards with Monitoring to let your GKE on-prem operations team monitor cluster health:

• Control plane status dashboard
• Pod status dashboard

This section describes how to create these dashboards. For more information about the dashboard creation process described in the following sections, see Managing dashboards by API.

Prerequisites

Your Google account must have the following permissions to create dashboards:

• monitoring.dashboards.create
• monitoring.dashboards.delete
• monitoring.dashboards.update

You'll have these permissions if your account has one of the following roles. You can check your permissions (in the Google Cloud console):

• monitoring.dashboardsEditor
• monitoring.editor
• Project editor
• Project owner

In addition, to use gcloud (gcloud CLI) to create dashboards, your Google Account must have the serviceusage.services.use permission.

Your account will have this permission if it has one of the following roles:

• roles/serviceusage.serviceUsageConsumer
• roles/serviceusage.serviceUsageAdmin
• roles/owner
• roles/editor
• Project editor
• Project owner

Create a control plane status dashboard

The GKE on-prem control plane consists of the API server, scheduler, controller manager, and etcd. To monitor the status of the control plane, create a dashboard that monitors the state of these components.

1. Download the dashboard configuration: control-plane-status.json

2. Create a custom dashboard with the configuration file by running the following command:

   gcloud monitoring dashboards create --config-from-file=control-plane-status.json

3. In the Google Cloud console, select Monitoring, or use the following button:

   Go to Monitoring

4. Select Resources > Dashboards and view the dashboard named Anthos GKE On-Prem Control Plane Status (preview). The control plane status of each user cluster is collected from separate namespaces within the admin cluster. The namespace_name field is the user cluster name.

   An service level objective (SLO) threshold of 0.999 is set in each chart.

5. Optionally create alerting policies.

   Click to see a sample dashboard.

   

Create a pod status dashboard

To create a dashboard that includes the phase of each Pod, and the restart times and resource usage of each container, perform the following steps.

1. Download the dashboard configuration: pod-status.json

2. Create a custom dashboard with the configuration file by running the following command:

   gcloud monitoring dashboards create --config-from-file=pod-status.json

3. In the Google Cloud console, select Monitoring, or use the following button:

   Go to Monitoring

4. Select Resources > Dashboards and view the dashboard named Anthos GKE On-Prem Pod Status (preview).

5. Optionally create alerting policies.

   Click to see a sample dashboard.

   

Accessing metrics data

You can choose from over 1,500 metrics by using Metrics Explorer. To access Metrics Explorer, do the following:

1. In the Google Cloud console, select Monitoring, or use the following button:

   Go to Monitoring

2. Select Resources > Metrics Explorer.

Accessing Monitoring metadata

Metadata is used indirectly via metrics. When you filter for metrics in Monitoring Metrics Explorer, you see options to filter metrics by metadata.systemLabels and metadata.userLabels. System labels are labels such as node name and Service name for Pods. User labels are labels assigned to Pods in the Kubernetes YAML files in the "metadata" section of the Pod specification.

Default Cloud Monitoring quota limits

GKE on-prem monitoring has a default limit of 6000 API calls per minute for each project. If you exceed this limit, your metrics may not be displayed. If you need a higher monitoring limit, request one through the Google Cloud console.

Known issue: Cloud Monitoring error condition

(Issue ID 159761921)

Under certain conditions, the default Cloud Monitoring pod, deployed by default in each new cluster, can become unresponsive. When clusters are upgraded, for example, storage data can become corrupted when pods in statefulset/prometheus-stackdriver-k8s are restarted.

Specifically, monitoring pod stackdriver-prometheus-k8s-0 can be caught in a loop when corrupted data prevents prometheus-stackdriver-sidecar writing to the cluster storage PersistentVolume.

You can manually diagnose and recover the error following the steps below.

Diagnosing the Cloud Monitoring failure

When the monitoring pod has failed, the logs will report the following:

{"log":"level=warn ts=2020-04-08T22:15:44.557Z caller=queue_manager.go:534 component=queue_manager msg=\"Unrecoverable error sending samples to remote storage\" err=\"rpc error: code = InvalidArgument desc = One or more TimeSeries could not be written: One or more points were written more frequently than the maximum sampling period configured for the metric.: timeSeries[0-114]; Unknown metric: kubernetes.io/anthos/scheduler_pending_pods: timeSeries[196-198]\"\n","stream":"stderr","time":"2020-04-08T22:15:44.558246866Z"}

{"log":"level=info ts=2020-04-08T22:15:44.656Z caller=queue_manager.go:229 component=queue_manager msg=\"Remote storage stopped.\"\n","stream":"stderr","time":"2020-04-08T22:15:44.656798666Z"}

{"log":"level=error ts=2020-04-08T22:15:44.663Z caller=main.go:603 err=\"corruption after 29032448 bytes: unexpected non-zero byte in padded page\"\n","stream":"stderr","time":"2020-04-08T22:15:44.663707748Z"}

{"log":"level=info ts=2020-04-08T22:15:44.663Z caller=main.go:605 msg=\"See you next time!\"\n","stream":"stderr","time":"2020-04-08T22:15:44.664000941Z"}

Recovering from the Cloud Monitoring error

To recover Cloud Monitoring manually:

1. Stop cluster monitoring. Scale down the stackdriver operator to prevent monitoring reconciliation:

   kubectl --kubeconfig /ADMIN_CLUSTER_KUBCONFIG --namespace kube-system scale deployment stackdriver-operator --replicas 0

2. Delete the monitoring pipeline workloads:

   kubectl --kubeconfig /ADMIN_CLUSTER_KUBCONFIG --namespace kube-system delete statefulset stackdriver-prometheus-k8s

3. Delete the monitoring pipeline PersistentVolumeClaims (PVCs):

   kubectl --kubeconfig /ADMIN_CLUSTER_KUBCONFIG --namespace kube-system delete pvc -l app=stackdriver-prometheus-k8s

4. Restart cluster monitoring. Scale up the stackdriver operator to reinstall a new monitoring pipeline and resume reconciliation:

   kubectl --kubeconfig /ADMIN_CLUSTER_KUBCONFIG --namespace kube-system scale deployment stackdriver-operator --replicas=1

Prometheus and Grafana

The following sections explain how to use Prometheus and Grafana with GKE on-prem clusters.

Enabling Prometheus and Grafana

Starting in GKE on-prem version 1.2, you can choose whether to enable or disable Prometheus and Grafana. In new user clusters, Prometheus and Grafana are disabled by default.

1. Your user cluster has a Monitoring object named monitoring-sample. Open the object for editing:

   kubectl --kubeconfig [USER_CLUSTER_KUBECONFIG] edit \
      monitoring monitoring-sample --namespace kube-system

   where [USER_CLUSTER_KUBECONFIG] is the kubeconfig file for your user cluster.

2. To enable Prometheus and Grafana, set enablePrometheus to true. To disable Prometheus and Grafana, set enablePrometheus to false:

   apiVersion: addons.k8s.io/v1alpha1
   kind: Monitoring
   metadata:
    labels:
      k8s-app: monitoring-operator
    name: monitoring-sample
    namespace: kube-system
   spec:
    channel: stable
    ...
    enablePrometheus: true

3. Save your changes by closing the editing session.

Known issue

In user clusters, Prometheus and Grafana get automatically disabled during upgrade. However, the configuration and metrics data are not lost.

To work around this issue, after the upgrade, open monitoring-sample for editing and set enablePrometheus to true.

Accessing monitoring metrics from Grafana dashboards

Grafana displays metrics gathered from your clusters. To view these metrics, you need to access Grafana's dashboards:

1. Get the name of the Grafana Pod running in a user cluster's kube-system namespace:

   kubectl --kubeconfig [USER_CLUSTER_KUBECONFIG] -n kube-system get pods

   where [USER_CLUSTER_KUBECONFIG] is the user cluster's kubeconfig file.

2. The container in the Grafana Pod listens on TCP port 3000. Forward a local port to port 3000 in the Pod, so that you can view Grafana's dashboards from a web browser.

   For example, suppose the name of the Pod is grafana-0. To forward port 50000 to port 3000 in the Pod, enter this command::

   kubectl --kubeconfig [USER_CLUSTER_KUBECONFIG] -n kube-system port-forward grafana-0 50000:3000

3. From a web browser, navigate to http://localhost:50000. The user cluster's Grafana Home Dashboard should load.

4. To access other dashboards, click the Home drop-down menu in the top-left corner of the page.

For an example of using Grafana, see Create a Grafana dashboard.

Accessing alerts

Prometheus Alertmanager collects alerts from the Prometheus server. You can view these alerts in a Grafana dashboard. To view the alerts, you need to access the dashboard:

1. The container in the alertmanager-0 Pod listens on TCP port 9093. Forward a local port to port 9093 in the Pod:

   kubectl --kubeconfig [USER_CLUSTER_KUBECONFIG] port-forward \
      -n kube-system alertmanager-0 50001:9093

2. From a web browser, navigate to http://localhost:50001.

Changing Prometheus Alertmanager configuration

You can change Prometheus Alertmanager's default configuration by editing your user cluster's monitoring.yaml file. You should do this if you want to direct alerts to a specific destination, rather than keep them in the dashboard. You can learn how to configure Alertmanager in Prometheus' Configuration documentation.

To change the Alertmanager configuration, perform the following steps:

1. Make a copy of the user cluster's monitoring.yaml manifest file:

   kubectl --kubeconfig [USER_CLUSTER_KUBECONFIG] -n kube-system \
      get monitoring monitoring-sample -o yaml > monitoring.yaml

2. To configure Alertmanager, make changes to the fields under spec.alertmanager.yml. When you're finished, save the changed manifest.

3. Apply the manifest to your cluster:

   kubectl apply --kubeconfig [USER_CLUSTER_KUBECONIFG] -f monitoring.yaml

Scaling Prometheus resources

The default monitoring configuration supports up to five nodes. For larger clusters, you can adjust the Prometheus Server resources. The recommendation is 50m cores of CPU and 500Mi of memory per cluster node. Make sure that your cluster contains two nodes, each with sufficient resources to fit Prometheus. For more information, refer to Resizing a user cluster.

To change Prometheus Server resources, perform the following steps:

1. Make a copy of the user cluster's monitoring.yaml manifest file:

   kubectl --kubeconfig [USER_CLUSTER_KUBECONFIG] -n kube-system get monitoring monitoring-sample -o yaml > monitoring.yaml

2. To override resources, make changes to the fields under spec.resourceOverride. When you're finished, save the changed manifest. Example:

   spec:
     resourceOverride:
     - component: Prometheus
       resources:
         requests:
           cpu: 300m
           memory: 3000Mi
         limits:
           cpu: 300m
           memory: 3000Mi
   

3. Apply the manifest to your cluster:

   kubectl --kubeconfig [USER_CLUSTER_KUBECONFIG] apply -f monitoring.yaml

Create a Grafana dashboard

You've deployed an application that exposes a metric, verified that the metric is exposed, and verified that Prometheus scrapes the metric. Now you can add the application-level metric to a custom Grafana dashboard.

To create a Grafana dashboard, perform the following steps:

1. If necessary, gain access to Grafana.
2. From the Home Dashboard, click the Home drop-down menu in the top-left corner of the page.
3. From the right-side menu, click New dashboard.
4. From the New panel section, click Graph. An empty graph dashboard appears.
5. Click Panel title, then click Edit. The bottom Graph panel opens to the Metrics tab.
6. From the Data Source drop-down menu, select user. Click Add query, and enter foo in the search field.
7. Click the Back to dashboard button in the top-right corner of the screen. Your dashboard is displayed.
8. To save the dashboard, click Save dashboard in the top-right corner of the screen. Choose a name for the dashboard, then click Save.

Disabling in-cluster monitoring

To disable in-cluster monitoring, revert the changes made to the monitoring-sample object:

1. Open the monitoring-sample object for editing:

   kubectl --kubeconfig USER_CLUSTER_KUBECONFIG edit \
      monitoring monitoring-sample --namespace kube-system

   Replace USER_CLUSTER_KUBECONFIG with the kubeconfig file for your user cluster.

2. To disable Prometheus and Grafana, set enablePrometheus to false:

      apiVersion: addons.k8s.io/v1alpha1
      kind: Monitoring
      metadata:
        labels:
          k8s-app: monitoring-operator
        name: monitoring-sample
        namespace: kube-system
      spec:
        channel: stable
        ...
        enablePrometheus: false
   

3. Save your changes by closing the editing session.

4. Confirm that the prometheus-0, prometheus-1 and grafana-0 statefulsets have been deleted:

   kubectl --kubeconfig USER_CLUSTER_KUBECONFIG get pods --namespace kube-system

Example: Adding application-level metrics to a Grafana dashboard

The following sections walk you through adding metrics for an application. In this section, you complete the following tasks:

• Deploy an example application that exposes a metric called foo.
• Verify that Prometheus exposes and scrapes the metric.
• Create a custom Grafana dashboard.

Deploy the example application

The example application runs in a single Pod. The Pod's container exposes a metric, foo, with a constant value of 40.

Create the following Pod manifest, pro-pod.yaml:

apiVersion: v1
kind: Pod
metadata:
  name: prometheus-example
  annotations:
    prometheus.io/scrape: 'true'
    prometheus.io/port: '8080'
    prometheus.io/path: '/metrics'
spec:
  containers:
  - image: registry.k8s.io/prometheus-dummy-exporter:v0.1.0
    name: prometheus-example
    command:
    - /bin/sh
    - -c
    - ./prometheus_dummy_exporter --metric-name=foo --metric-value=40 --port=8080

Then apply the Pod manifest to your user cluster:

kubectl --kubeconfig [USER_CLUSTER_KUBECONFIG] apply -f pro-pod.yaml

Verify that the metric is exposed and scraped

1. The container in the prometheus-example pod listens on TCP port 8080. Forward a local port to port 8080 in the Pod:

   kubectl --kubeconfig [USER_CLUSTER_KUBECONFIG] port-forward prometheus-example 50002:8080

2. To verify that the application exposes the metric, run the following command:

   curl localhost:50002/metrics | grep foo
   

   The command returns the following output:

   # HELP foo Custom metric
   # TYPE foo gauge
   foo 40

3. The container in the prometheus-0 Pod listens on TCP port 9090. Forward a local port to port 9090 in the Pod:

   kubectl --kubeconfig [USER_CLUSTER_KUBECONFIG] port-forward prometheus-0 50003:9090

4. To verify that Prometheus is scraping the metric, navigate to http://localhost:50003/targets, which should take you to the prometheus-0 Pod under the prometheus-io-pods target group.

5. To view metrics in Prometheus, navigate to http://localhost:50003/graph. From the search field, enter foo, then click Execute. The page should display the metric.