MySQL alert rules

• prod: "metric"
• cate: "mysql"
• recover_config.judge_type: 1 (metric type)
• Required keys.valueKey: the alias of the numeric column in the SELECT statement (usually called value)

OSS edition limitation

The OSS edition of n9e's MySQL data source does not support time variables such as $from/$to/$__timeFilter (the bound macros.Macro is a no-op implementation, so the variables enter the SQL as-is and cause a syntax error).

Correct approach: use MySQL's native time functions, for example:

• Last N minutes: WHERE created_at >= NOW() - INTERVAL 5 MINUTE
• Last N hours: WHERE created_at >= NOW() - INTERVAL 1 HOUR
• From the start of today until now: WHERE DATE(created_at) = CURDATE()

triggers hard rules (must read)

• exp is required and is the only field the alert engine evaluates (a rule without exp will never fire once created, with no error whatsoever)
• Variable syntax for this data source: $<ref>.<valueKey alias>, e.g. $A.value > 10; with only one valueKey you may omit the alias and write $A directly, but with multiple valueKeys you must include the alias (a bare $A has an undefined value)
• mode is fixed at 1 (expression mode; the frontend displays exp as-is); join multiple conditions with && / ||, e.g. "$A.value > 10 && $B.value < 5"

rule_config structure

{
  "rule_config": {
    "queries": [
      {
        "ref": "A",
        "sql": "SELECT count(*) AS value FROM orders WHERE created_at >= NOW() - INTERVAL 5 MINUTE AND status = 'failed'",
        "keys": {
          "valueKey": "value",
          "labelKey": ""
        },
        "interval": 60
      }
    ],
    "triggers": [
      {
        "mode": 1,
        "exp": "$A.value > 10",
        "severity": 2,
        "recover_config": {"judge_type": 1}
      }
    ]
  }
}

query field reference

Multi-dimension example (grouped by host)

{
  "queries": [
    {
      "ref": "A",
      "sql": "SELECT host AS label, count(*) AS value FROM errors WHERE created_at >= NOW() - INTERVAL 5 MINUTE GROUP BY host",
      "keys": {"valueKey": "value", "labelKey": "label"},
      "interval": 60
    }
  ],
  "triggers": [
    {
      "mode": 1,
      "exp": "$A.value > 100",
      "severity": 2,
      "recover_config": {"judge_type": 1}
    }
  ]
}