Cluster Monitoring with the CockroachDB Operator

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Despite CockroachDB's various built-in safeguards against failure, it is critical to actively monitor the overall health and performance of a cluster running in production and to create alerting rules that promptly send notifications when there are events that require investigation or intervention.

Configure Prometheus

Every node of a CockroachDB cluster exports granular timeseries metrics formatted for easy integration with Prometheus, an open source tool for storing, aggregating, and querying timeseries data. This section shows you how to orchestrate Prometheus as part of your Kubernetes cluster and pull these metrics into Prometheus for external monitoring.

This guidance is based on CoreOS's Prometheus Operator, which allows a Prometheus instance to be managed using built-in Kubernetes concepts.

1. From your local workstation, edit the cockroachdb service to add the prometheus: cockroachdb label:

   kubectl label svc cockroachdb prometheus=cockroachdb
   

   service/cockroachdb labeled
   

   This ensures that only the cockroachdb (not the cockroach-public service) is being monitored by a Prometheus job.

2. Determine the latest version of CoreOS's Prometheus Operator and run the following to download and apply the latest bundle.yaml definition file:

   Note:

   Be sure to specify the latest CoreOS Prometheus Operator version in the following command, in place of this example's use of version v0.82.0.

   kubectl apply \
   -f https://raw.githubusercontent.com/prometheus-operator/prometheus-operator/v0.82.0/bundle.yaml \
   --server-side
   

   customresourcedefinition.apiextensions.k8s.io/alertmanagers.monitoring.coreos.com serverside-applied
   customresourcedefinition.apiextensions.k8s.io/podmonitors.monitoring.coreos.com serverside-applied
   customresourcedefinition.apiextensions.k8s.io/probes.monitoring.coreos.com serverside-applied
   customresourcedefinition.apiextensions.k8s.io/prometheuses.monitoring.coreos.com serverside-applied
   customresourcedefinition.apiextensions.k8s.io/prometheusrules.monitoring.coreos.com serverside-applied
   customresourcedefinition.apiextensions.k8s.io/servicemonitors.monitoring.coreos.com serverside-applied
   customresourcedefinition.apiextensions.k8s.io/thanosrulers.monitoring.coreos.com serverside-applied
   clusterrolebinding.rbac.authorization.k8s.io/prometheus-operator serverside-applied
   clusterrole.rbac.authorization.k8s.io/prometheus-operator serverside-applied
   deployment.apps/prometheus-operator serverside-applied
   serviceaccount/prometheus-operator serverside-applied
   service/prometheus-operator serverside-applied
   

3. Confirm that the prometheus-operator has started:

   kubectl get deploy prometheus-operator
   

   NAME                  READY   UP-TO-DATE   AVAILABLE   AGE
   prometheus-operator   1/1     1            1           27s
   

4. Download our Prometheus manifest:

   curl -O https://raw.githubusercontent.com/cockroachdb/cockroach/master/cloud/kubernetes/prometheus/prometheus.yaml
   

5. Apply the Prometheus manifest. This creates the various objects necessary to run a Prometheus instance:

   kubectl apply -f prometheus.yaml
   

   serviceaccount/prometheus created
   clusterrole.rbac.authorization.k8s.io/prometheus created
   clusterrolebinding.rbac.authorization.k8s.io/prometheus created
   servicemonitor.monitoring.coreos.com/cockroachdb created
   prometheus.monitoring.coreos.com/cockroachdb created
   

6. Access the Prometheus UI locally and verify that CockroachDB is feeding data into Prometheus:

   1. Port-forward from your local machine to the pod running Prometheus:

      kubectl port-forward prometheus-cockroachdb-0 9090
      

   2. Go to http://localhost:9090 in your browser.

   3. To verify that each CockroachDB node is connected to Prometheus, go to Status > Targets. The screen should look like this:

      

   4. To verify that data is being collected, go to Graph, enter the sys_uptime variable in the field, click Execute, and then click the Graph tab. The screen should like this:

      

   Note:

   Prometheus auto-completes CockroachDB time series metrics for you, but if you want to see a full listing, with descriptions, port-forward as described in Access the DB Console and then point your browser to http://localhost:8080/_status/vars.

For more details on using the Prometheus UI, see their official documentation.

Configure Alertmanager

Active monitoring helps you spot problems early, but it is also essential to send notifications when there are events that require investigation or intervention. This section shows you how to use Alertmanager and CockroachDB's starter alerting rules to do this.

1. Download our alertmanager-config.yaml configuration file:

   curl -O https://raw.githubusercontent.com/cockroachdb/cockroach/master/cloud/kubernetes/prometheus/alertmanager-config.yaml
   

2. Edit the alertmanager-config.yaml file to specify the desired receivers for notifications. Initially, the file contains a placeholder web hook.

3. Add this configuration to the Kubernetes cluster as a secret, renaming it to alertmanager.yaml and labeling it to make it easier to find:

   kubectl create secret generic alertmanager-cockroachdb \
   --from-file=alertmanager.yaml=alertmanager-config.yaml
   

   secret/alertmanager-cockroachdb created
   

   kubectl label secret alertmanager-cockroachdb app=cockroachdb
   

   secret/alertmanager-cockroachdb labeled
   

   Warning:

   The name of the secret, alertmanager-cockroachdb, must match the name used in the alertmanager.yaml file. If they differ, the Alertmanager instance will start without configuration, and nothing will happen.

4. Use our alertmanager.yaml file to create the various objects necessary to run an Alertmanager instance, including a ClusterIP service so that Prometheus can forward alerts:

   kubectl apply \
   -f https://raw.githubusercontent.com/cockroachdb/cockroach/master/cloud/kubernetes/prometheus/alertmanager.yaml
   

   alertmanager.monitoring.coreos.com/cockroachdb created
   service/alertmanager-cockroachdb created
   

5. Verify that Alertmanager is running:

   1. Port-forward from your local machine to the pod running Alertmanager:

      kubectl port-forward alertmanager-cockroachdb-0 9093
      

   2. Go to http://localhost:9093 in your browser. The screen should look like this:

      

6. Ensure that the Alertmanagers are visible to Prometheus by opening http://localhost:9090/status. The screen should look like this:

   

7. Add CockroachDB's starter alerting rules:

   kubectl apply \
   -f https://raw.githubusercontent.com/cockroachdb/cockroach/master/cloud/kubernetes/prometheus/alert-rules.yaml
   

   prometheusrule.monitoring.coreos.com/prometheus-cockroachdb-rules created
   

8. Ensure that the rules are visible to Prometheus by opening http://localhost:9090/rules. The screen should look like this:

   

9. Verify that the TestAlertManager example alert is firing by opening http://localhost:9090/alerts. The screen should look like this:

   

10. To remove the example alert:

    1. Use the kubectl edit command to open the rules for editing:

       kubectl edit prometheusrules prometheus-cockroachdb-rules
       

    2. Remove the dummy.rules block and save the file:

       - name: rules/dummy.rules
         rules:
         - alert: TestAlertManager
           expr: vector(1)
       

Monitor the operator

The CockroachDB operator automatically exposes Prometheus-style metrics that you can monitor to observe its operations.

Metrics can be collected from the operator via HTTP requests (port 8080 by default) against the /metrics endpoint. The response will describe the current node metrics, for example:

...
# HELP node_decommissioning Whether a CockroachDB node is decommissioning.
# TYPE node_decommissioning gauge
node_decommissioning{node="cockroachdb-nvq2l"} 0
node_decommissioning{node="cockroachdb-pmp45"} 0
node_decommissioning{node="cockroachdb-q6784"} 0
node_decommissioning{node="cockroachdb-r4wz8"} 0
...

Configure logging

You can use the operator to configure the CockroachDB logging system. This allows you to output logs to configurable log sinks such as file or network logging destinations.

The logging configuration is defined in a ConfigMap object, using a key named logs.yaml. For example:

apiVersion: v1
data:
  logs.yaml: |
    sinks:
      file-groups:
        dev:
          channels: DEV
          filter: WARNING
kind: ConfigMap
metadata:
  name: logconfig
  namespace: cockroach-ns

The above configuration overrides the default logging configuration and saves debug-level logs (the DEV log channel) to disk for troubleshooting.

The ConfigMap name must match the cockroachdb.crdbCluster.loggingConfigMapName object in the values file used to deploy the cluster:

cockroachdb:
  crdbCluster:
    loggingConfigMapName: logconfig

By default, the operator also modifies the default logging configuration with the following:

sinks:
  stderr:
    channels: {INFO: "HEALTH, OPS", WARNING: "STORAGE, DEV"}
      redact: true

This outputs logging events in the OPS channel to a cockroach-stderr.log file.

Example: Configuring a troubleshooting log file on pods

In this example, CockroachDB has already been deployed on a Kubernetes cluster. Override the default logging configuration to output DEV logs to a cockroach-dev.log file.

1. Create a ConfigMap named logconfig. Note that namespace is set to the cockroach-ns namespace:

   apiVersion: v1
   data:
     logs.yaml: |
       sinks:
         file-groups:
           dev:
             channels: DEV
             filter: WARNING
   kind: ConfigMap
   metadata:
     name: logconfig
     namespace: cockroach-ns
   

   For simplicity, also name the YAML file logconfig.yaml.

   Note:

   The ConfigMap key is not related to the ConfigMap name or YAML filename, and must be named logging.yaml.

   This configuration outputs DEV logs that have severity WARNING to a cockroach-dev.log file on each pod.

2. Apply the ConfigMap to the cluster:

   kubectl apply -f logconfig.yaml
   

   configmap/logconfig created
   

3. Add the name of the ConfigMap in loggingConfigMapName to the values file:

   cockroachdb:
     crdbCluster:
       loggingConfigMapName: logconfig
   

4. Apply the new settings to the cluster:

   helm upgrade --reuse-values $CRDBCLUSTER ./cockroachdb-parent/charts/cockroachdb --values ./cockroachdb-parent/charts/cockroachdb/values.yaml -n $NAMESPACE
   

   The changes will be rolled out to each pod.

5. See the log files available on a pod:

   kubectl exec cockroachdb-2 -- ls cockroach-data/logs
   

   cockroach-dev.cockroachdb-2.unknownuser.2022-05-02T19_03_03Z.000001.log
   cockroach-dev.log
   cockroach-health.cockroachdb-2.unknownuser.2022-05-02T18_53_01Z.000001.log
   cockroach-health.log
   cockroach-pebble.cockroachdb-2.unknownuser.2022-05-02T18_52_48Z.000001.log
   cockroach-pebble.log
   cockroach-stderr.cockroachdb-2.unknownuser.2022-05-02T18_52_48Z.000001.log
   cockroach-stderr.cockroachdb-2.unknownuser.2022-05-02T19_03_03Z.000001.log
   cockroach-stderr.cockroachdb-2.unknownuser.2022-05-02T20_04_03Z.000001.log
   cockroach-stderr.log
   cockroach.cockroachdb-2.unknownuser.2022-05-02T18_52_48Z.000001.log
   cockroach.log
   ...
   

6. View a specific log file:

   kubectl exec cockroachdb-2 -- cat cockroach-data/logs/cockroach-dev.log