r/launch_template: fix setting ipv6_addresses

aws/resource_aws_launch_template.go

@@ -758,7 +758,6 @@ func getMonitoring(m *ec2.LaunchTemplatesMonitoring) []interface{} {
 func getNetworkInterfaces(n []*ec2.LaunchTemplateInstanceNetworkInterfaceSpecification) []interface{} {
 	s := []interface{}{}
 	for _, v := range n {
-		var ipv6Addresses []string
 		var ipv4Addresses []string
 
 		networkInterface := map[string]interface{}{
@@ -773,11 +772,19 @@ func getNetworkInterfaces(n []*ec2.LaunchTemplateInstanceNetworkInterfaceSpecifi
 			"subnet_id":                   aws.StringValue(v.SubnetId),
 		}
 
-		for _, address := range v.Ipv6Addresses {
-			ipv6Addresses = append(ipv6Addresses, aws.StringValue(address.Ipv6Address))
-		}
-		if len(ipv6Addresses) > 0 {
-			networkInterface["ipv6_addresses"] = ipv6Addresses
+		if len(v.Ipv6Addresses) > 0 {
+			raw, ok := networkInterface["ipv6_addresses"]
+			if !ok {
+				raw = schema.NewSet(schema.HashString, nil)
+			}
+
+			list := raw.(*schema.Set)
+
+			for _, address := range v.Ipv6Addresses {
+				list.Add(aws.StringValue(address.Ipv6Address))
+			}
+
+			networkInterface["ipv6_addresses"] = list
 		}
 
 		for _, address := range v.PrivateIpAddresses {

aws/resource_aws_launch_template_test.go

@@ -250,6 +250,27 @@ func TestAccAWSLaunchTemplate_networkInterface(t *testing.T) {
 	})
 }
 
+func TestAccAWSLaunchTemplate_networkInterface_ipv6Addresses(t *testing.T) {
+	var template ec2.LaunchTemplate
+	resName := "aws_launch_template.test"
+
+	resource.Test(t, resource.TestCase{
+		PreCheck:     func() { testAccPreCheck(t) },
+		Providers:    testAccProviders,
+		CheckDestroy: testAccCheckAWSLaunchTemplateDestroy,
+		Steps: []resource.TestStep{
+			{
+				Config: testAccAWSLaunchTemplateConfig_networkInterface_ipv6Addresses,
+				Check: resource.ComposeTestCheckFunc(
+					testAccCheckAWSLaunchTemplateExists(resName, &template),
+					resource.TestCheckResourceAttr(resName, "network_interfaces.#", "1"),
+					resource.TestCheckResourceAttr(resName, "network_interfaces.0.ipv6_addresses.#", "2"),
+				),
+			},
+		},
+	})
+}
+
 func testAccCheckAWSLaunchTemplateExists(n string, t *ec2.LaunchTemplate) resource.TestCheckFunc {
 	return func(s *terraform.State) error {
 		rs, ok := s.RootModule().Resources[n]
@@ -531,6 +552,19 @@ resource "aws_launch_template" "test" {
 }
 `
 
+const testAccAWSLaunchTemplateConfig_networkInterface_ipv6Addresses = `
+resource "aws_launch_template" "test" {
+  name = "network-interface-ipv6-addresses-launch-template"
+
+  network_interfaces {
+    ipv6_addresses = [
+      "0:0:0:0:0:ffff:a01:5",
+      "0:0:0:0:0:ffff:a01:6",
+    ]
+  }
+}
+`
+
 const testAccAWSLaunchTemplateConfig_asg_basic = `
 data "aws_ami" "test_ami" {
   most_recent = true