go-sundheit Custom DNS check Example

custom-dns-check-example.go

import (
  "context"
  "fmt"
  "net"
  "time"

  "github.com/AppsFlyer/go-sundheit/checks"
  "github.com/pkg/errors"
)

func NewDNSCheck(host string, timeout time.Duration, minRequiredResults int) checks.Check {
  resolver := net.DefaultResolver

  return &checks.CustomCheck{
     CheckName: "resolve." + host,
     CheckFunc: func() (details interface{}, err error) {
        ctx, cancel := context.WithTimeout(context.TODO(), timeout)
        defer cancel()

        addrs, err := resolver.LookupHost(ctx, host)
        resolvedCount := len(addrs)
        details = fmt.Sprintf("[%d] results were resolved", resolvedCount)
        if err != nil {
           return
        }
        if resolvedCount < minRequiredResults {
           err = errors.Errorf("[%s] lookup returned %d results, but requires at least %d", host, resolvedCount, minRequiredResults)
        }

        return
     },
  }
}