Enable Shards for TidbMonitor

This document describes how to use shards for TidbMonitor.

Shards

TidbMonitor collects monitoring data for a single TiDB cluster or multiple TiDB clusters. When the amount of monitoring data is large, the computing capacity of one TidbMonitor might hit a bottleneck. In this case, it is recommended to use shards of Prometheus Modulus. This feature performs hashmod on __address__ to divide the monitoring data of multiple targets (Targets) into multiple TidbMonitor Pods.

To use shards for TidbMonitor, you need a data aggregation plan. The Thanos method is recommended.

Enable shards

To enable shards for TidbMonitor, you need to specify the shards field. For example:

apiVersion: pingcap.com/v1alpha1
kind: TidbMonitor
metadata:
  name: monitor
spec:
  replicas: 1
  shards: 2
  clusters:
    - name: basic
  prometheus:
    baseImage: prom/prometheus
    version: v2.27.1
  initializer:
    baseImage: pingcap/tidb-monitor-initializer
    version: v5.2.1
  reloader:
    baseImage: pingcap/tidb-monitor-reloader
    version: v1.0.1
  prometheusReloader:
    baseImage: quay.io/prometheus-operator/prometheus-config-reloader
    version: v0.49.0
  imagePullPolicy: IfNotPresent

Note

The number of Pods corresponding to TidbMonitor is the product of replicas and shards. For example, when replicas is 1 and shards is 2, TiDB Operator creates 2 TidbMonitor Pods.
After shards is changed, Targets are reallocated. However, the monitoring data already stored on the Pods is not reallocated.

For details on the configuration, refer to shards example.