move hostname check to util

cli/commands.go

@@ -24,37 +24,6 @@ import (
 )
 
 const defaultRegistry = "docker.io"
-const clusterNameMaxSize int = 35
-
-// Make sure a cluster name is also a valid host name according to RFC 1123.
-// We further restrict the length of the cluster name to shorter than 'clusterNameMaxSize'
-// so that we can construct the host names based on the cluster name, and still stay
-// within the 64 characters limit.
-func checkClusterName(name string) error {
-       if len(name) > clusterNameMaxSize {
-	       return fmt.Errorf("cluster name is too long")
-       }
-
-       if name[0] == '-' || name[len(name) - 1] == '-' {
-	       return fmt.Errorf("cluster name can not start or end with - (dash)")
-       }
-
-
-       for _ , c := range name {
-		switch {
-			case '0' <= c && c <= '9':
-			case 'a' <= c && c <= 'z':
-			case 'A' <= c && c <= 'Z':
-			case c == '-':
-				break;
-		default:
-	       		return fmt.Errorf("cluster name contains charaters other than 'Aa-Zz', '0-9' or '-'")
-
-       		}
-	}
-
-       return nil
-}
 
 // CheckTools checks if the docker API server is responding
 func CheckTools(c *cli.Context) error {
@@ -76,8 +45,8 @@ func CheckTools(c *cli.Context) error {
 // CreateCluster creates a new single-node cluster container and initializes the cluster directory
 func CreateCluster(c *cli.Context) error {
 
-	if err := checkClusterName(c.String("name")); err != nil {
-		return err;
+	if err := CheckClusterName(c.String("name")); err != nil {
+		return err
 	}
 
 	// define image

cli/util.go

@@ -1,6 +1,7 @@
 package run
 
 import (
+	"fmt"
 	"math/rand"
 	"strings"
 	"time"
@@ -36,3 +37,35 @@ func GenerateRandomString(n int) string {
 
 	return sb.String()
 }
+
+/*** Cluster Name Validation ***/
+const clusterNameMaxSize int = 35
+
+// CheckClusterName ensures that a cluster name is also a valid host name according to RFC 1123.
+// We further restrict the length of the cluster name to maximum 'clusterNameMaxSize'
+// so that we can construct the host names based on the cluster name, and still stay
+// within the 64 characters limit.
+func CheckClusterName(name string) error {
+	if len(name) > clusterNameMaxSize {
+		return fmt.Errorf("[ERROR] Cluster name is too long")
+	}
+
+	if name[0] == '-' || name[len(name)-1] == '-' {
+		return fmt.Errorf("[ERROR] Cluster name can not start or end with - (dash)")
+	}
+
+	for _, c := range name {
+		switch {
+		case '0' <= c && c <= '9':
+		case 'a' <= c && c <= 'z':
+		case 'A' <= c && c <= 'Z':
+		case c == '-':
+			break
+		default:
+			return fmt.Errorf("[ERROR] Cluster name contains characters other than 'Aa-Zz', '0-9' or '-'")
+
+		}
+	}
+
+	return nil
+}