Prometheus/Alertmanager告警路由问题：无法按规则分发至对应邮箱

一、两类告警均发送至默认接收器的原因 #

你的Alertmanager路由匹配规则存在语法错误：在Alertmanager的标签匹配逻辑中，相等匹配必须使用==操作符，而你配置里写的是=（alertname="EPG_build_too_long"、alertname="APP_build_too_long"）。这种错误写法会导致APP_build_too_long告警无法匹配到对应的路由规则，最终触发默认接收器EmailNotifications-EPG。

修正匹配语法后，告警就能按预期路由到对应接收器。

二、通用邮箱配置迁移至global段的可行性 #

完全可以将SMTP通用配置迁移到global段，Alertmanager支持全局定义SMTP参数，避免重复配置。修改后的完整配置示例如下：

global:
  resolve_timeout: 1m
  # 全局SMTP通用配置
  smtp_from: "Monitor <monitor@company.com>"
  smtp_smarthost: mail.company.com:25
  smtp_auth_username: monitor@company.com
  smtp_auth_identity: monitor@company.com
  smtp_auth_password: "..."
route:
  receiver: "EmailNotifications-EPG"
  routes:
    - receiver: "EmailNotifications-EPG"
      matchers:
        - alertname == "EPG_build_too_long"
    - receiver: "EmailNotifications-APP"
      matchers:
        - alertname == "APP_build_too_long"
receivers:
- name: "EmailNotifications-EPG"
  email_configs:
  - to: e1@company.com,e2@company.com
    send_resolved: true
- name: "EmailNotifications-APP"
  email_configs:
  - to: e1@company.com,e3@company.com
    send_resolved: true

内容的提问来源于stack exchange，提问作者user1876484