Merge pull request #26977 from mtt88/b-aws_lb_target_group-duplicate-…

…names

r/aws_lb_target_group - check no target group with the same name exists

.changelog/26977.txt

@@ -0,0 +1,3 @@
+```release-note:bug
+resource/aws_lb_target_group: When creating a new target group, return an error if there is an existing target group with the same name. Use [`terraform import`](https://developer.hashicorp.com/terraform/cli/commands/import) for existing target groups
+```

internal/service/elbv2/find.go

@@ -63,3 +63,19 @@ func FindTargetGroupByARN(conn *elbv2.ELBV2, arn string) (*elbv2.TargetGroup, er
 
 	return nil, nil
 }
+
+func FindTargetGroupByName(conn *elbv2.ELBV2, name string) (*elbv2.TargetGroup, error) {
+	output, err := conn.DescribeTargetGroups(&elbv2.DescribeTargetGroupsInput{
+		Names: aws.StringSlice([]string{name}),
+	})
+
+	if err != nil {
+		return nil, err
+	}
+
+	if len(output.TargetGroups) == 0 {
+		return nil, nil
+	}
+
+	return output.TargetGroups[0], nil
+}

internal/service/elbv2/target_group.go

@@ -334,6 +334,14 @@ func resourceTargetGroupCreate(d *schema.ResourceData, meta interface{}) error {
 		groupName = resource.PrefixedUniqueId("tf-")
 	}
 
+	existingTg, err := FindTargetGroupByName(conn, groupName)
+	if err != nil && !tfawserr.ErrCodeEquals(err, elbv2.ErrCodeTargetGroupNotFoundException) {
+		return fmt.Errorf("finding target group by name (%s): %w", groupName, err)
+	}
+	if existingTg != nil {
+		return fmt.Errorf("target group with name (%s) already exists", groupName)
+	}
+
 	params := &elbv2.CreateTargetGroupInput{
 		Name:       aws.String(groupName),
 		TargetType: aws.String(d.Get("target_type").(string)),

internal/service/elbv2/target_group_test.go

@@ -2154,6 +2154,32 @@ func TestAccELBV2TargetGroup_ALBAlias_updateStickinessEnabled(t *testing.T) {
 	})
 }
 
+func TestAccELBV2TargetGroup_Name_noDuplicates(t *testing.T) {
+	var targetGroup elbv2.TargetGroup
+	tgName := sdkacctest.RandomWithPrefix(acctest.ResourcePrefix)
+	resourceName := "aws_lb_target_group.first"
+
+	resource.ParallelTest(t, resource.TestCase{
+		PreCheck:                 func() { acctest.PreCheck(t) },
+		ErrorCheck:               acctest.ErrorCheck(t, elbv2.EndpointsID),
+		ProtoV5ProviderFactories: acctest.ProtoV5ProviderFactories,
+		CheckDestroy:             testAccCheckTargetGroupDestroy,
+		Steps: []resource.TestStep{
+			{
+				Config: testAccTargetGroupConfig_duplicateNameFirst(tgName),
+				Check: resource.ComposeAggregateTestCheckFunc(
+					testAccCheckTargetGroupExists(resourceName, &targetGroup),
+					resource.TestCheckResourceAttr(resourceName, "name", tgName),
+				),
+			},
+			{
+				Config:      testAccTargetGroupConfig_duplicateNameFirstAndSecond(tgName),
+				ExpectError: regexp.MustCompile("target group with name (.*?) already exist"),
+			},
+		},
+	})
+}
+
 func testAccTargetGroupConfig_albDefaults(rName string) string {
 	return fmt.Sprintf(`
 resource "aws_lb_target_group" "test" {
@@ -3779,6 +3805,63 @@ resource "aws_vpc" "test" {
 }`, rName)
 }
 
+func testAccTargetGroupConfig_duplicateNameFirst(rName string) string {
+	return fmt.Sprintf(`
+resource "aws_lb_target_group" "first" {
+  name     = %[1]q
+  port     = 443
+  protocol = "HTTPS"
+  vpc_id   = aws_vpc.test.id
+
+  tags = {
+    Name = %[1]q
+  }
+}
+
+resource "aws_vpc" "test" {
+  cidr_block = "10.0.0.0/16"
+
+  tags = {
+    Name = %[1]q
+  }
+}
+`, rName)
+}
+
+func testAccTargetGroupConfig_duplicateNameFirstAndSecond(rName string) string {
+	return fmt.Sprintf(`
+resource "aws_lb_target_group" "first" {
+  name     = %[1]q
+  port     = 443
+  protocol = "HTTPS"
+  vpc_id   = aws_vpc.test.id
+
+  tags = {
+    Name = %[1]q
+  }
+}
+
+resource "aws_lb_target_group" "second" {
+  name     = %[1]q
+  port     = 443
+  protocol = "HTTPS"
+  vpc_id   = aws_vpc.test.id
+
+  tags = {
+    Name = %[1]q
+  }
+}
+
+resource "aws_vpc" "test" {
+  cidr_block = "10.0.0.0/16"
+
+  tags = {
+    Name = %[1]q
+  }
+}
+`, rName)
+}
+
 func testAccCheckATargetGroupDestroy(s *terraform.State) error {
 	conn := acctest.Provider.Meta().(*conns.AWSClient).ELBV2Conn()