delete_on_termination on ENI has to be optional

aws/resource_aws_launch_template.go

@@ -381,8 +381,14 @@ func resourceAwsLaunchTemplate() *schema.Resource {
 							ValidateFunc:     validateTypeStringNullableBoolean,
 						},
 						"delete_on_termination": {
-							Type:     schema.TypeBool,
-							Optional: true,
+							// Use TypeString to allow an "unspecified" value,
+							// since TypeBool only has true/false with false default.
+							// The conversion from bare true/false values in
+							// configurations to TypeString value is currently safe.
+							Type:             schema.TypeString,
+							Optional:         true,
+							DiffSuppressFunc: suppressEquivalentTypeStringBoolean,
+							ValidateFunc:     validateTypeStringNullableBoolean,
 						},
 						"description": {
 							Type:     schema.TypeString,
@@ -956,19 +962,22 @@ func getNetworkInterfaces(n []*ec2.LaunchTemplateInstanceNetworkInterfaceSpecifi
 		var ipv4Addresses []string
 
 		networkInterface := map[string]interface{}{
-			"delete_on_termination": aws.BoolValue(v.DeleteOnTermination),
-			"description":           aws.StringValue(v.Description),
-			"device_index":          aws.Int64Value(v.DeviceIndex),
-			"ipv4_address_count":    aws.Int64Value(v.SecondaryPrivateIpAddressCount),
-			"ipv6_address_count":    aws.Int64Value(v.Ipv6AddressCount),
-			"network_interface_id":  aws.StringValue(v.NetworkInterfaceId),
-			"private_ip_address":    aws.StringValue(v.PrivateIpAddress),
-			"subnet_id":             aws.StringValue(v.SubnetId),
+			"description":          aws.StringValue(v.Description),
+			"device_index":         aws.Int64Value(v.DeviceIndex),
+			"ipv4_address_count":   aws.Int64Value(v.SecondaryPrivateIpAddressCount),
+			"ipv6_address_count":   aws.Int64Value(v.Ipv6AddressCount),
+			"network_interface_id": aws.StringValue(v.NetworkInterfaceId),
+			"private_ip_address":   aws.StringValue(v.PrivateIpAddress),
+			"subnet_id":            aws.StringValue(v.SubnetId),
 		}
 		if v.AssociatePublicIpAddress != nil {
 			networkInterface["associate_public_ip_address"] = strconv.FormatBool(aws.BoolValue(v.AssociatePublicIpAddress))
 		}
 
+		if v.DeleteOnTermination != nil {
+			networkInterface["delete_on_termination"] = strconv.FormatBool(aws.BoolValue(v.DeleteOnTermination))
+		}
+
 		if len(v.Ipv6Addresses) > 0 {
 			raw, ok := networkInterface["ipv6_addresses"]
 			if !ok {
@@ -1310,8 +1319,12 @@ func readNetworkInterfacesFromConfig(ni map[string]interface{}) (*ec2.LaunchTemp
 	var privateIpAddress string
 	networkInterface := &ec2.LaunchTemplateInstanceNetworkInterfaceSpecificationRequest{}
 
-	if v, ok := ni["delete_on_termination"]; ok {
-		networkInterface.DeleteOnTermination = aws.Bool(v.(bool))
+	if v, ok := ni["delete_on_termination"]; ok && v.(string) != "" {
+		vBool, err := strconv.ParseBool(v.(string))
+		if err != nil {
+			return nil, fmt.Errorf("error converting delete_on_termination %q from string to boolean: %w", v.(string), err)
+		}
+		networkInterface.DeleteOnTermination = aws.Bool(vBool)
 	}
 
 	if v, ok := ni["description"].(string); ok && v != "" {

aws/resource_aws_launch_template_test.go

@@ -284,6 +284,61 @@ func TestAccAWSLaunchTemplate_ElasticInferenceAccelerator(t *testing.T) {
 	})
 }
 
+func TestAccAWSLaunchTemplate_NetworkInterfaces_DeleteOnTermination(t *testing.T) {
+	var template ec2.LaunchTemplate
+	rName := acctest.RandomWithPrefix("tf-acc-test")
+	resourceName := "aws_launch_template.test"
+
+	resource.ParallelTest(t, resource.TestCase{
+		PreCheck:     func() { testAccPreCheck(t) },
+		Providers:    testAccProviders,
+		CheckDestroy: testAccCheckAWSLaunchTemplateDestroy,
+		Steps: []resource.TestStep{
+			{
+				Config: testAccAWSLaunchTemplateConfig_NetworkInterfaces_DeleteOnTermination(rName, "true"),
+				Check: resource.ComposeTestCheckFunc(
+					testAccCheckAWSLaunchTemplateExists(resourceName, &template),
+					resource.TestCheckResourceAttr(resourceName, "network_interfaces.#", "1"),
+					resource.TestCheckResourceAttr(resourceName, "network_interfaces.0.security_groups.#", "1"),
+					resource.TestCheckResourceAttr(resourceName, "network_interfaces.0.delete_on_termination", "true"),
+				),
+			},
+			{
+				Config: testAccAWSLaunchTemplateConfig_NetworkInterfaces_DeleteOnTermination(rName, "false"),
+				Check: resource.ComposeTestCheckFunc(
+					testAccCheckAWSLaunchTemplateExists(resourceName, &template),
+					resource.TestCheckResourceAttr(resourceName, "network_interfaces.#", "1"),
+					resource.TestCheckResourceAttr(resourceName, "network_interfaces.0.security_groups.#", "1"),
+					resource.TestCheckResourceAttr(resourceName, "network_interfaces.0.delete_on_termination", "false"),
+				),
+			},
+			{
+				Config: testAccAWSLaunchTemplateConfig_NetworkInterfaces_DeleteOnTermination(rName, "\"\""),
+				Check: resource.ComposeTestCheckFunc(
+					testAccCheckAWSLaunchTemplateExists(resourceName, &template),
+					resource.TestCheckResourceAttr(resourceName, "network_interfaces.#", "1"),
+					resource.TestCheckResourceAttr(resourceName, "network_interfaces.0.security_groups.#", "1"),
+					resource.TestCheckResourceAttr(resourceName, "network_interfaces.0.delete_on_termination", ""),
+				),
+			},
+			{
+				Config: testAccAWSLaunchTemplateConfig_NetworkInterfaces_DeleteOnTermination(rName, "null"),
+				Check: resource.ComposeTestCheckFunc(
+					testAccCheckAWSLaunchTemplateExists(resourceName, &template),
+					resource.TestCheckResourceAttr(resourceName, "network_interfaces.#", "1"),
+					resource.TestCheckResourceAttr(resourceName, "network_interfaces.0.security_groups.#", "1"),
+					resource.TestCheckResourceAttr(resourceName, "network_interfaces.0.delete_on_termination", ""),
+				),
+			},
+			{
+				ResourceName:      resourceName,
+				ImportState:       true,
+				ImportStateVerify: true,
+			},
+		},
+	})
+}
+
 func TestAccAWSLaunchTemplate_data(t *testing.T) {
 	var template ec2.LaunchTemplate
 	resourceName := "aws_launch_template.test"
@@ -312,6 +367,7 @@ func TestAccAWSLaunchTemplate_data(t *testing.T) {
 					resource.TestCheckResourceAttr(resourceName, "monitoring.#", "1"),
 					resource.TestCheckResourceAttr(resourceName, "network_interfaces.#", "1"),
 					resource.TestCheckResourceAttr(resourceName, "network_interfaces.0.security_groups.#", "1"),
+					resource.TestCheckResourceAttr(resourceName, "network_interfaces.0.delete_on_termination", ""),
 					resource.TestCheckResourceAttr(resourceName, "placement.#", "1"),
 					resource.TestCheckResourceAttrSet(resourceName, "ram_disk_id"),
 					resource.TestCheckResourceAttr(resourceName, "vpc_security_group_ids.#", "1"),
@@ -624,6 +680,7 @@ func TestAccAWSLaunchTemplate_networkInterface(t *testing.T) {
 					resource.TestCheckResourceAttr(resourceName, "network_interfaces.#", "1"),
 					resource.TestCheckResourceAttrSet(resourceName, "network_interfaces.0.network_interface_id"),
 					resource.TestCheckResourceAttr(resourceName, "network_interfaces.0.associate_public_ip_address", ""),
+					resource.TestCheckResourceAttr(resourceName, "network_interfaces.0.delete_on_termination", ""),
 					resource.TestCheckResourceAttr(resourceName, "network_interfaces.0.ipv4_address_count", "2"),
 				),
 			},
@@ -1033,6 +1090,20 @@ resource "aws_autoscaling_group" "test" {
 `, rName, deleteOnTermination, rName)
 }
 
+func testAccAWSLaunchTemplateConfig_NetworkInterfaces_DeleteOnTermination(rName string, deleteOnTermination string) string {
+	return fmt.Sprintf(`
+resource "aws_launch_template" "test" {
+  name          = %q
+
+  network_interfaces {
+    network_interface_id = "eni-123456ab"
+    security_groups = ["sg-1a23bc45"]
+    delete_on_termination = %s
+  }
+}
+`, rName, deleteOnTermination)
+}
+
 func testAccAWSLaunchTemplateConfig_EbsOptimized(rName, ebsOptimized string) string {
 	return fmt.Sprintf(`
 resource "aws_launch_template" "test" {

website/docs/guides/version-3-upgrade.html.md

@@ -185,6 +185,41 @@ resource "aws_emr_cluster" "example" {
 }
 ```
 
+## Resource: aws_launch_template
+
+### network_interfaces.delete_on_termination Argument type change
+
+
+Enforce `delete_on_termination` to `false` if it was not set previously to keep the (incorrect) behavior to treat no value as `false`.
+
+For example, given this previous configuration:
+
+```hcl
+resource "aws_launch_template" "example" {
+  # ... other configuration ...
+
+  network_interfaces {
+    # ... other configuration ...
+
+    delete_on_termination = null
+  }
+}
+```
+
+An updated configuration:
+
+```hcl
+resource "aws_launch_template" "example" {
+  # ... other configuration ...
+
+  network_interfaces {
+    # ... other configuration ...
+
+    delete_on_termination = false
+  }
+}
+```
+
 ## Resource: aws_lb_listener_rule
 
 ### condition.field and condition.values Arguments Removal