Chapter 9. Troubleshooting monitoring issues 9.1. Investigating why user-defined metrics are unavailable ServiceMonitor resources enable you to determine how to use the metrics exposed by a service in user-defined projects. Follow the steps outlined in this procedure if you have created a ServiceMonitor resource but cannot see any corresponding metrics in the Metrics UI. Prerequisites You have access to the cluster as a user with the cluster-admin role. You have installed the OpenShift CLI ( oc ). You have enabled and configured monitoring for user-defined workloads. You have created the user-workload-monitoring-config ConfigMap object. You have created a ServiceMonitor resource. Procedure Check that the corresponding labels match in the service and ServiceMonitor resource configurations. Obtain the label defined in the service. The following example queries the prometheus-example-app service in the ns1 project: USD oc -n ns1 get service prometheus-example-app -o yaml Example output labels: app: prometheus-example-app Check that the matchLabels app label in the ServiceMonitor resource configuration matches the label output in the preceding step: USD oc -n ns1 get servicemonitor prometheus-example-monitor -o yaml Example output Note You can check service and ServiceMonitor resource labels as a developer with view permissions for the project. Inspect the logs for the Prometheus Operator in the openshift-user-workload-monitoring project. List the pods in the openshift-user-workload-monitoring project: USD oc -n openshift-user-workload-monitoring get pods Example output NAME READY STATUS RESTARTS AGE prometheus-operator-776fcbbd56-2nbfm 2/2 Running 0 132m prometheus-user-workload-0 5/5 Running 1 132m prometheus-user-workload-1 5/5 Running 1 132m thanos-ruler-user-workload-0 3/3 Running 0 132m thanos-ruler-user-workload-1 3/3 Running 0 132m Obtain the logs from the prometheus-operator container in the prometheus-operator pod. In the following example, the pod is called prometheus-operator-776fcbbd56-2nbfm : USD oc -n openshift-user-workload-monitoring logs prometheus-operator-776fcbbd56-2nbfm -c prometheus-operator If there is a issue with the service monitor, the logs might include an error similar to this example: level=warn ts=2020-08-10T11:48:20.906739623Z caller=operator.go:1829 component=prometheusoperator msg="skipping servicemonitor" error="it accesses file system via bearer token file which Prometheus specification prohibits" servicemonitor=eagle/eagle namespace=openshift-user-workload-monitoring prometheus=user-workload Review the target status for your project in the Prometheus UI directly. Establish port-forwarding to the Prometheus instance in the openshift-user-workload-monitoring project: USD oc port-forward -n openshift-user-workload-monitoring pod/prometheus-user-workload-0 9090 Open http://localhost:9090/targets in a web browser and review the status of the target for your project directly in the Prometheus UI. Check for error messages relating to the target. Configure debug level logging for the Prometheus Operator in the openshift-user-workload-monitoring project. Edit the user-workload-monitoring-config ConfigMap object in the openshift-user-workload-monitoring project: USD oc -n openshift-user-workload-monitoring edit configmap user-workload-monitoring-config Add logLevel: debug for prometheusOperator under data/config.yaml to set the log level to debug : apiVersion: v1 kind: ConfigMap metadata: name: user-workload-monitoring-config namespace: openshift-user-workload-monitoring data: config.yaml: | prometheusOperator: logLevel: debug Save the file to apply the changes. Note The prometheus-operator in the openshift-user-workload-monitoring project restarts automatically when you apply the log-level change. Confirm that the debug log-level has been applied to the prometheus-operator deployment in the openshift-user-workload-monitoring project: USD oc -n openshift-user-workload-monitoring get deploy prometheus-operator -o yaml | grep "log-level" Example output - --log-level=debug Debug level logging will show all calls made by the Prometheus Operator. Check that the prometheus-operator pod is running: USD oc -n openshift-user-workload-monitoring get pods Note If an unrecognized Prometheus Operator loglevel value is included in the config map, the prometheus-operator pod might not restart successfully. Review the debug logs to see if the Prometheus Operator is using the ServiceMonitor resource. Review the logs for other related errors. Additional resources Creating a user-defined workload monitoring config map See Specifying how a service is monitored for details on how to create a ServiceMonitor or PodMonitor resource 9.2. Determining why Prometheus is consuming a lot of disk space Developers can create labels to define attributes for metrics in the form of key-value pairs. The number of potential key-value pairs corresponds to the number of possible values for an attribute. An attribute that has an unlimited number of potential values is called an unbound attribute. For example, a customer_id attribute is unbound because it has an infinite number of possible values. Every assigned key-value pair has a unique time series. The use of many unbound attributes in labels can result in an exponential increase in the number of time series created. This can impact Prometheus performance and can consume a lot of disk space. You can use the following measures when Prometheus consumes a lot of disk: Check the number of scrape samples that are being collected. Check the time series database (TSDB) status in the Prometheus UI for more information on which labels are creating the most time series. This requires cluster administrator privileges. Reduce the number of unique time series that are created by reducing the number of unbound attributes that are assigned to user-defined metrics. Note Using attributes that are bound to a limited set of possible values reduces the number of potential key-value pair combinations. Enforce limits on the number of samples that can be scraped across user-defined projects. This requires cluster administrator privileges. Prerequisites You have access to the cluster as a user with the cluster-admin role. You have installed the OpenShift CLI ( oc ). Procedure In the Administrator perspective, navigate to Observe Metrics . Run the following Prometheus Query Language (PromQL) query in the Expression field. This returns the ten metrics that have the highest number of scrape samples: topk(10,count by (job)({__name__=~".+"})) Investigate the number of unbound label values assigned to metrics with higher than expected scrape sample counts. If the metrics relate to a user-defined project , review the metrics key-value pairs assigned to your workload. These are implemented through Prometheus client libraries at the application level. Try to limit the number of unbound attributes referenced in your labels. If the metrics relate to a core OpenShift Container Platform project , create a Red Hat support case on the Red Hat Customer Portal . Check the TSDB status in the Prometheus UI. In the Administrator perspective, navigate to Networking Routes . Select the openshift-monitoring project in the Project list. Select the URL in the prometheus-k8s row to open the login page for the Prometheus UI. Choose Log in with OpenShift to log in using your OpenShift Container Platform credentials. In the Prometheus UI, navigate to Status TSDB Status . Additional resources See Setting a scrape sample limit for user-defined projects for details on how to set a scrape sample limit and create related alerting rules Submitting a support case

Commands:
oc -n ns1 get service prometheus-example-app -o yaml
labels: app: prometheus-example-app
oc -n ns1 get servicemonitor prometheus-example-monitor -o yaml
spec: endpoints: - interval: 30s port: web scheme: http selector: matchLabels: app: prometheus-example-app
oc -n openshift-user-workload-monitoring get pods
NAME READY STATUS RESTARTS AGE prometheus-operator-776fcbbd56-2nbfm 2/2 Running 0 132m prometheus-user-workload-0 5/5 Running 1 132m prometheus-user-workload-1 5/5 Running 1 132m thanos-ruler-user-workload-0 3/3 Running 0 132m thanos-ruler-user-workload-1 3/3 Running 0 132m
oc -n openshift-user-workload-monitoring logs prometheus-operator-776fcbbd56-2nbfm -c prometheus-operator
level=warn ts=2020-08-10T11:48:20.906739623Z caller=operator.go:1829 component=prometheusoperator msg="skipping servicemonitor" error="it accesses file system via bearer token file which Prometheus specification prohibits" servicemonitor=eagle/eagle namespace=openshift-user-workload-monitoring prometheus=user-workload
oc port-forward -n openshift-user-workload-monitoring pod/prometheus-user-workload-0 9090
oc -n openshift-user-workload-monitoring edit configmap user-workload-monitoring-config
apiVersion: v1 kind: ConfigMap metadata: name: user-workload-monitoring-config namespace: openshift-user-workload-monitoring data: config.yaml: | prometheusOperator: logLevel: debug
oc -n openshift-user-workload-monitoring get deploy prometheus-operator -o yaml | grep "log-level"
- --log-level=debug
oc -n openshift-user-workload-monitoring get pods
topk(10,count by (job)({__name__=~".+"}))