tags: initial implementation of tags

Author: nicolehanjing

Diff for: pkg/providers/v2/tags.go

@@ -30,7 +30,9 @@ import (
 const (
 	// TagNameKubernetesClusterPrefix is the tag name we use to differentiate multiple
 	// logically independent clusters running in the same AZ.
-	// tag format: kubernetes.io/cluster/=<clusterName>
+	// tag format: kubernetes.io/cluster/<clusterID> = shared|owned
+	// The tag key = TagNameKubernetesClusterPrefix + clusterID
+	// The tag value is an ownership value
 	TagNameKubernetesClusterPrefix = "kubernetes.io/cluster/"
 
 	// createTag* is configuration of exponential backoff for CreateTag call. We
@@ -57,7 +59,7 @@ func findClusterName(tags []*ec2.Tag) (string, error) {
 	for _, tag := range tags {
 		tagKey := aws.StringValue(tag.Key)
 		if strings.HasPrefix(tagKey, TagNameKubernetesClusterPrefix) {
-			name := aws.StringValue(tag.Value)
+			name := strings.TrimPrefix(tagKey, TagNameKubernetesClusterPrefix)
 			if clusterName != "" {
 				return "", fmt.Errorf("Found multiple cluster tags with prefix %s (%q and %q)", TagNameKubernetesClusterPrefix, clusterName, name)
 			}
@@ -104,7 +106,7 @@ func (t *awsTagging) hasClusterTag(tags []*ec2.Tag) bool {
 
 	for _, tag := range tags {
 		tagKey := aws.StringValue(tag.Key)
-		if (tagKey == TagNameKubernetesClusterPrefix) && (aws.StringValue(tag.Value) == t.ClusterName) {
+		if tagKey == (TagNameKubernetesClusterPrefix + t.ClusterName) {
 			return true
 		}
 	}

Diff for: pkg/providers/v2/tags_test.go

@@ -23,7 +23,7 @@ import (
 )
 
 func TestFindClusterName(t *testing.T) {
-	grid := []struct {
+	testCases := []struct {
 		Tags                map[string]string
 		ExpectedClusterName string
 		ExpectError         bool
@@ -33,7 +33,19 @@ func TestFindClusterName(t *testing.T) {
 		},
 		{
 			Tags: map[string]string{
-				TagNameKubernetesClusterPrefix: TestClusterID,
+				TagNameKubernetesClusterPrefix + TestClusterID: "owned",
+			},
+			ExpectedClusterName: TestClusterID,
+		},
+		{
+			Tags: map[string]string{
+				TagNameKubernetesClusterPrefix + TestClusterID: "shared",
+			},
+			ExpectedClusterName: TestClusterID,
+		},
+		{
+			Tags: map[string]string{
+				TagNameKubernetesClusterPrefix + TestClusterID: "",
 			},
 			ExpectedClusterName: TestClusterID,
 		},
@@ -43,26 +55,33 @@ func TestFindClusterName(t *testing.T) {
 			},
 			ExpectedClusterName: "",
 		},
+		{
+			Tags: map[string]string{
+				TagNameKubernetesClusterPrefix + "a": "",
+				TagNameKubernetesClusterPrefix + "b": "",
+			},
+			ExpectError: true,
+		},
 	}
-	for _, g := range grid {
+	for _, testCase := range testCases {
 		var ec2Tags []*ec2.Tag
-		for k, v := range g.Tags {
+		for k, v := range testCase.Tags {
 			ec2Tags = append(ec2Tags, &ec2.Tag{Key: aws.String(k), Value: aws.String(v)})
 		}
 		clusterName, err := findClusterName(ec2Tags)
-		if g.ExpectError {
+		if testCase.ExpectError {
 			if err == nil {
-				t.Errorf("expected error for tags %v", g.Tags)
+				t.Errorf("expected error for tags %v", testCase.Tags)
 				continue
 			}
 		} else {
 			if err != nil {
-				t.Errorf("unexpected error for tags %v: %v", g.Tags, err)
+				t.Errorf("unexpected error for tags %v: %v", testCase.Tags, err)
 				continue
 			}
 
-			if g.ExpectedClusterName != clusterName {
-				t.Errorf("unexpected new clusterName for tags %v: %s vs %s", g.Tags, g.ExpectedClusterName, clusterName)
+			if testCase.ExpectedClusterName != clusterName {
+				t.Errorf("unexpected new clusterName for tags %v: %s vs %s", testCase.Tags, testCase.ExpectedClusterName, clusterName)
 				continue
 			}
 		}