With JSON formatted logs:
```
$ jq 'select(.error) | select(.error | contains("Prometheus"))' tidb.log
{
  "level": "INFO",
  "time": "2023/01/27 10:00:35.554 +01:00",
  "caller": "data_slow_query.go:67",
  "message": "Failed to get Slow Query Stats",
  "error": "[domain:9009]Prometheus address is not set in PD and etcd"
}
{
  "level": "INFO",
  "time": "2023/01/27 10:01:36.223 +01:00",
  "caller": "data_window.go:257",
  "message": "Error exists when getting the SQL Metric.",
  "error": "[domain:9009]Prometheus address is not set in PD and etcd"
}
{
  "level": "INFO",
  "time": "2023/01/27 10:02:36.225 +01:00",
  "caller": "data_window.go:257",
  "message": "Error exists when getting the SQL Metric.",
  "error": "[domain:9009]Prometheus address is not set in PD and etcd"
}
```