Monitoring KubeDB Operator

KubeDB has native support for monitoring via Prometheus. You can use builtin Prometheus scrapper or CoreOS Prometheus Operator to monitor KubeDB supported databases as well as KubeDB operator itself. This tutorial will show you what metrics KubeDB operator exports and how to enable monitoring for the operator itself.

Overview

KubeDB operator pod runs an Extension API Server which self hosts admission webhooks such as MutatingAdmissionWebhook and ValidatingAdmissionWebhook. The extension API server exports some metrics in /metrics path of TLS secured 8443 port. KubeDB installation process creates a service with same name as KubeDB operator (i.e. kubedb-operator) in same namespace as the operator pod. Prometheus server can use api endpoint of this service to scrape those metrics.

Exported Metrics

KubeDB operator exports following metrics.

API Server Metrics:

Metric Name Uses
apiserver_audit_event_total Counter of audit events generated and sent to the audit backend.
apiserver_client_certificate_expiration_seconds Distribution of the remaining lifetime on the certificate used to authenticate a request.
apiserver_current_inflight_requests Maximal number of currently used inflight request limit of this apiserver per request kind in last second.
apiserver_request_count Counter of apiserver requests broken out for each verb, API resource, client, and HTTP response contentType and code.
apiserver_request_latencies Response latency distribution in microseconds for each verb, resource and subresource.
apiserver_request_latencies_summary Response latency summary in microseconds for each verb, resource and subresource.
authenticated_user_requests Counter of authenticated requests broken out by username.

Go Metrics:

Metric Name Uses
go_gc_duration_seconds A summary of the GC invocation durations.
go_goroutines Number of goroutines that currently exist.
go_memstats_alloc_bytes Number of bytes allocated and still in use.
go_memstats_alloc_bytes_total Total number of bytes allocated, even if freed.
go_memstats_buck_hash_sys_bytes Number of bytes used by the profiling bucket hash table.
go_memstats_frees_total Total number of frees.
go_memstats_gc_sys_bytes Number of bytes used for garbage collection system metadata.
go_memstats_heap_alloc_bytes Number of heap bytes allocated and still in use.
go_memstats_heap_idle_bytes Number of heap bytes waiting to be used.
go_memstats_heap_inuse_bytes Number of heap bytes that are in use.
go_memstats_heap_objects Number of allocated objects.
go_memstats_heap_released_bytes_total Total number of heap bytes released to OS.
go_memstats_heap_sys_bytes Number of heap bytes obtained from system.
go_memstats_last_gc_time_seconds Number of seconds since 1970 of last garbage collection.
go_memstats_lookups_total Total number of pointer lookups.
go_memstats_mallocs_total Total number of mallocs.
go_memstats_mcache_inuse_bytes Number of bytes in use by mcache structures.
go_memstats_mcache_sys_bytes Number of bytes used for mcache structures obtained from system.
go_memstats_mspan_inuse_bytes Number of bytes in use by mspan structures.
go_memstats_mspan_sys_bytes Number of bytes used for mspan structures obtained from system.
go_memstats_next_gc_bytes Number of heap bytes when next garbage collection will take place.
go_memstats_other_sys_bytes Number of bytes used for other system allocations.
go_memstats_stack_inuse_bytes Number of bytes in use by the stack allocator.
go_memstats_stack_sys_bytes Number of bytes obtained from system for stack allocator.
go_memstats_sys_bytes Number of bytes obtained by system. Sum of all system allocations.

HTTP Metrics:

Metrics Uses
http_request_duration_microseconds The HTTP request latencies in microseconds.
http_request_size_bytes The HTTP request sizes in bytes.
http_requests_total Total number of HTTP requests made.
http_response_size_bytes The HTTP response sizes in bytes.

Process Metrics:

Metric Name Uses
process_cpu_seconds_total Total user and system CPU time spent in seconds.
process_max_fds Maximum number of open file descriptors.
process_open_fds Number of open file descriptors.
process_resident_memory_bytes Resident memory size in bytes.
process_start_time_seconds Start time of the process since unix epoch in seconds.
process_virtual_memory_bytes Virtual memory size in bytes.

How to Enable Monitoring

You can enable operator monitoring through some flags while installing or upgrading or updating KubeDB via both script and Helm. You can also choose which monitoring agent to use for monitoring. KubeDB will configure respective resources accordingly. Here, are the list of available flags and their uses,

Script Flag Helm Values Acceptable Values Default Uses
--monitoring-enable monitoring.enabled true or false false Specify whether to monitor KubeDB operator.
--monitoring-agent monitoring.agent prometheus.io/builtin or prometheus.io/coreos-operator none Specify which monitoring agent to use for monitoring KubeDB operator.
--prometheus-namespace monitoring.prometheus.namespace any namespace same namespace as KubeDB operator Specify the namespace where Prometheus server is running or will be deployed
--servicemonitor-label monitoring.serviceMonitor.labels any label For Helm installation, app: <generated app name> and release: <release name>. For script installation, app: kubedb Specify the labels for ServiceMonitor. Prometheus crd will select ServiceMonitor using these labels. Only usable when monitoring agent is prometheus.io/coreos-operator.

You have to provides these flags while installing or upgrading or updating KubeDB operator. Here, are examples for both script and Helm installation process are given which enable monitoring with prometheus.io/coreos-operator Prometheuse server for operator metrics.

Helm:

$ helm install appscode/kubedb --name kubedb-operator --version 0.11.0 --namespace kube-system \
  --set monitoring.enabled=true \
  --set monitoring.agent=prometheus.io/coreos-operator \
  --set monitoring.prometheus.namespace=monitoring \
  --set monitoring.serviceMonitor.labels.k8s-app=prometheus

Script:

$ curl -fsSL https://raw.githubusercontent.com/kubedb/cli/0.11.0/hack/deploy/kubedb.sh | bash -s -- \
  --monitoring-enable=true \
  --monitoring-agent=prometheus.io/coreos-operator \
  --prometheus-namespace=monitoring \
  --servicemonitor-label=k8s-app=prometheus

Next Steps

  • Learn how to monitor KubeDB operator using built-in Prometheus from here.
  • Learn how to monitor KubeDB operator using CoreOS Prometheus operator from here.

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