k8s容器内部通过Prometheus Operator部署MySQL Exporter监控k8s集群外部的MySQL

写在前面

在按照下面步骤操作之前，请先确保服务器已经部署k8s，prometheus，prometheus operator，关于这些环境的部署，可以自行查找相关资料安装部署，本文档便不在此赘述。

关于prometheus监控这部分，大致的系统架构图如下，感兴趣的同学可以自行研究一下，这里就不再具体说明。

1、问题说明

由于部分业务系统使用MySQL数据库存储数据，同时该数据库部署在k8s集群之外，但是prometheus operator部署在k8s集群内部，这里就涉及到了如何监控k8s集群外部的MySQL实例的问题。MySQL的监控可以使用prometheus的mysql-exporter暴露metrics，对于mysql处在k8s集群外部的场景，可以在创建Deployment时指定监控的数据源实例的IP地址为MySQL所在主机的IP地址，以此来暴露外部MySQL服务到k8s集群中。

2、部署操作

2.1、创建监控数据库的用户并授权

这里主要是创建mysql-exporter连接mysql需要的用户，同时并授予相应权限，操作SQL如下：

# 查看数据库密码长度，确保密码符合要求
SHOW VARIABLES LIKE 'validate_password%';

# 创建用户并授权，这里以exporter用户为例，密码长度与上述查询长度保持一致
create user 'exporter'@'%' identified with mysql_native_password by 'admin@321';
GRANT ALL PRIVILEGES ON *.* TO 'exporter'@'%' with grant option;
flush privileges;

2.2、k8s集群创建mysql-exporter的Deployment

创建mysql-exporter容器，利用上一步创建的账户密码信息，通过DATA_SOURCE_NAME环境变量传入连接mysql实例的信息，注意需要暴露mysql-exporter的9104端口。

---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: mysqld-exporter
  namespace: prometheus-exporter
  labels:
    app: mysqld-exporter
spec:
  replicas: 1
  selector:
    matchLabels:
      app: mysqld-exporter
  template:
    metadata:
      labels:
        app: mysqld-exporter
    spec:
      containers:
      - name: mysqld-exporter
        image: prom/mysqld-exporter
        imagePullPolicy: IfNotPresent
        env:
        # 此处为mysql-exporter指定监控的数据库地址以及对应的用户名、密码，这里监控的数据库IP地址为10.26.124.16:3306
        - name: DATA_SOURCE_NAME
          value: exporter:admin@321@(10.26.124.16:3306)/mysql
        ports:
        - containerPort: 9104

部署成功图如下：

2.3、k8s集群创建mysql-exporter的Service

---
apiVersion: v1
kind: Service
metadata:
  labels:
    app: mysqld-exporter
  name: mysqld-exporter
  namespace: prometheus-exporter
spec:
  type: ClusterIP
  ports:
  - name: metrics
    port: 9104
    protocol: TCP
    targetPort: 9104
  selector:
   app: mysqld-exporter

部署成功图如下：

2.4、创建ServiceMonitor

---
apiVersion: monitoring.coreos.com/v1
kind: ServiceMonitor
metadata:
  labels:
    app: mysqld-exporter
    prometheus: k8s
  name: prometheus-mysqld-exporter
  namespace: prometheus-exporter
spec:
  endpoints:
    - interval: 1m
      port: metrics
      params:
        target:
          - '10.26.124.16:3306'
      relabelings:
        - sourceLabels: [__param_target]
          targetLabel: instance
  namespaceSelector:
    matchNames:
      - prometheus-exporter
  selector:
    matchLabels:
      app: mysqld-exporter

部署成功图如下：

2.5、添加PrometheusRule监控规则

---
apiVersion: monitoring.coreos.com/v1
kind: PrometheusRule
metadata:
  labels:
    prometheus: k8s
    role: alert-rules
  name: mysql-exporter-rules
  namespace: kubesphere-monitoring-system
spec:
  groups:
    - name: mysql-exporter
      rules:
        - alert: MysqlDown
          annotations:
            description: |-
              MySQL instance is down on {{ $labels.instance }}
                VALUE = {{ $value }}
                LABELS = {{ $labels }}
            summary: 'MySQL down (instance {{ $labels.instance }})'
          expr: mysql_up == 0
          for: 0m
          labels:
            severity: critical
        - alert: MysqlSlaveIoThreadNotRunning
          annotations:
            description: |-
              MySQL Slave IO thread not running on {{ $labels.instance }}
                VALUE = {{ $value }}
                LABELS = {{ $labels }}
            summary: >-
              MySQL Slave IO thread not running (instance {{ $labels.instance
              }})
          expr: >-
            mysql_slave_status_master_server_id > 0 and ON (instance)
            mysql_slave_status_slave_io_running == 0
          for: 0m
          labels:
            severity: critical
        - alert: MysqlSlaveSqlThreadNotRunning
          annotations:
            description: |-
              MySQL Slave SQL thread not running on {{ $labels.instance }}
                VALUE = {{ $value }}
                LABELS = {{ $labels }}
            summary: >-
              MySQL Slave SQL thread not running (instance {{ $labels.instance
              }})
          expr: >-
            mysql_slave_status_master_server_id > 0 and ON (instance)
            mysql_slave_status_slave_sql_running == 0
          for: 0m
          labels:
            severity: critical

部署成功图如下：