feat: support select ip randomly

diamond.go

@@ -1,6 +1,7 @@
 package aliacm
 
 import (
+	"math/rand"
 	"time"
 
 	"github.com/sirupsen/logrus"
@@ -63,6 +64,7 @@ type Diamond struct {
 	c       *cast.Cast
 	units   []Unit
 	errHook Hook
+	r       *rand.Rand
 }
 
 // New 产生Diamond实例
@@ -85,9 +87,14 @@ func New(addr, tenant, accessKey, secretKey string) (*Diamond, error) {
 	if err != nil {
 		return nil, err
 	}
+
+	s := rand.NewSource(time.Now().UnixNano())
+	r := rand.New(s)
+
 	d := &Diamond{
 		option: option,
 		c:      c,
+		r:      r,
 	}
 	return d, nil
 }

query_ip.go

@@ -18,7 +18,10 @@ func (d *Diamond) QueryIP() (string, error) {
 	if !response.Success() {
 		return "", errors.New(response.String())
 	}
-	ips := strings.Split(response.String(), "\n")
-	// TODO: randomly select one from ip list?
-	return ips[0], nil
+	ips := strings.Split(strings.TrimSpace(response.String()), "\n")
+	if len(ips) > 0 {
+		idx := d.r.Intn(len(ips))
+		return ips[idx], nil
+	}
+	return "", nil
 }

time.go

@@ -1,6 +1,8 @@
 package aliacm
 
-import "time"
+import (
+	"time"
+)
 
 const (
 	apiTimeout = 3 * time.Second