fix: Fix crash during read due to key-only tags in aws_lightsail_instance

.changelog/37587.txt

@@ -0,0 +1,3 @@
+```release-note:bug
+resource/aws_lightsail_instance: Fix crash when reading a resource that has a key-only tag
+```

internal/service/lightsail/generate.go

@@ -1,7 +1,7 @@
 // Copyright (c) HashiCorp, Inc.
 // SPDX-License-Identifier: MPL-2.0
 
-//go:generate go run ../../generate/tags/main.go -AWSSDKVersion=2 -ListTagsInIDElem=ResourceName -ServiceTagsSlice -TagInIDElem=ResourceName -UpdateTags  -CreateTags
+//go:generate go run ../../generate/tags/main.go -AWSSDKVersion=2 -ServiceTagsSlice -TagInIDElem=ResourceName -CreateTags -UpdateTags
 //go:generate go run ../../generate/servicepackage/main.go
 // ONLY generate directives and package declaration! Do not add anything else to this file.
 

internal/service/lightsail/instance.go

@@ -28,7 +28,7 @@ import (
 )
 
 // @SDKResource("aws_lightsail_instance", name="Instance")
-// @Tags(identifierAttribute="id")
+// @Tags(identifierAttribute="id", resourceType="Instance")
 func ResourceInstance() *schema.Resource {
 	return &schema.Resource{
 		CreateWithoutTimeout: resourceInstanceCreate,

internal/service/lightsail/instance_test.go

@@ -150,8 +150,14 @@ func TestAccLightsailInstance_tags(t *testing.T) {
 					resource.TestCheckResourceAttrSet(resourceName, "bundle_id"),
 					resource.TestCheckResourceAttrSet(resourceName, "key_pair_name"),
 					resource.TestCheckResourceAttr(resourceName, acctest.CtTagsPercent, acctest.Ct1),
+					resource.TestCheckResourceAttr(resourceName, "tags.Name", "tf-test"),
 				),
 			},
+			{
+				ResourceName:      resourceName,
+				ImportState:       true,
+				ImportStateVerify: true,
+			},
 			{
 				Config: testAccInstanceConfig_tags2(rName),
 				Check: resource.ComposeAggregateTestCheckFunc(
@@ -161,6 +167,60 @@ func TestAccLightsailInstance_tags(t *testing.T) {
 					resource.TestCheckResourceAttrSet(resourceName, "bundle_id"),
 					resource.TestCheckResourceAttrSet(resourceName, "key_pair_name"),
 					resource.TestCheckResourceAttr(resourceName, acctest.CtTagsPercent, acctest.Ct2),
+					resource.TestCheckResourceAttr(resourceName, "tags.Name", "tf-test"),
+					resource.TestCheckResourceAttr(resourceName, "tags.ExtraName", "tf-test"),
+				),
+			},
+		},
+	})
+}
+
+func TestAccLightsailInstance_keyOnlyTags(t *testing.T) {
+	ctx := acctest.Context(t)
+	rName := sdkacctest.RandomWithPrefix(acctest.ResourcePrefix)
+	resourceName := "aws_lightsail_instance.test"
+
+	resource.ParallelTest(t, resource.TestCase{
+		PreCheck: func() {
+			acctest.PreCheck(ctx, t)
+			acctest.PreCheckPartitionHasService(t, strings.ToLower(lightsail.ServiceID))
+			testAccPreCheck(ctx, t)
+		},
+		ErrorCheck:               acctest.ErrorCheck(t, strings.ToLower(lightsail.ServiceID)),
+		ProtoV5ProviderFactories: acctest.ProtoV5ProviderFactories,
+		CheckDestroy:             testAccCheckInstanceDestroy(ctx),
+		Steps: []resource.TestStep{
+			{
+				Config: testAccInstanceConfig_keyOnlyTags1(rName),
+				Check: resource.ComposeAggregateTestCheckFunc(
+					testAccCheckInstanceExists(ctx, resourceName),
+					resource.TestCheckResourceAttrSet(resourceName, names.AttrAvailabilityZone),
+					resource.TestCheckResourceAttrSet(resourceName, "blueprint_id"),
+					resource.TestCheckResourceAttrSet(resourceName, "bundle_id"),
+					resource.TestCheckResourceAttrSet(resourceName, "key_pair_name"),
+					resource.TestCheckResourceAttr(resourceName, acctest.CtTagsPercent, acctest.Ct2),
+					resource.TestCheckResourceAttr(resourceName, "tags.Name", "tf-test"),
+					resource.TestCheckResourceAttr(resourceName, "tags.EmptyTag1", ""),
+				),
+			},
+			{
+				ResourceName:      resourceName,
+				ImportState:       true,
+				ImportStateVerify: true,
+			},
+			{
+				Config: testAccInstanceConfig_keyOnlyTags2(rName),
+				Check: resource.ComposeAggregateTestCheckFunc(
+					testAccCheckInstanceExists(ctx, resourceName),
+					resource.TestCheckResourceAttrSet(resourceName, names.AttrAvailabilityZone),
+					resource.TestCheckResourceAttrSet(resourceName, "blueprint_id"),
+					resource.TestCheckResourceAttrSet(resourceName, "bundle_id"),
+					resource.TestCheckResourceAttrSet(resourceName, "key_pair_name"),
+					resource.TestCheckResourceAttr(resourceName, acctest.CtTagsPercent, acctest.Ct4),
+					resource.TestCheckResourceAttr(resourceName, "tags.Name", "tf-test"),
+					resource.TestCheckResourceAttr(resourceName, "tags.ExtraName", "tf-test"),
+					resource.TestCheckResourceAttr(resourceName, "tags.EmptyTag1", "NotEmptyAnymore"),
+					resource.TestCheckResourceAttr(resourceName, "tags.EmptyTag2", ""),
 				),
 			},
 		},
@@ -468,6 +528,44 @@ resource "aws_lightsail_instance" "test" {
 `, rName))
 }
 
+func testAccInstanceConfig_keyOnlyTags1(rName string) string {
+	return acctest.ConfigCompose(
+		testAccInstanceConfigBase(),
+		fmt.Sprintf(`
+resource "aws_lightsail_instance" "test" {
+  name              = "%s"
+  availability_zone = data.aws_availability_zones.available.names[0]
+  blueprint_id      = "amazon_linux_2"
+  bundle_id         = "nano_3_0"
+
+  tags = {
+    Name      = "tf-test"
+    EmptyTag1 = ""
+  }
+}
+`, rName))
+}
+
+func testAccInstanceConfig_keyOnlyTags2(rName string) string {
+	return acctest.ConfigCompose(
+		testAccInstanceConfigBase(),
+		fmt.Sprintf(`
+resource "aws_lightsail_instance" "test" {
+  name              = "%s"
+  availability_zone = data.aws_availability_zones.available.names[0]
+  blueprint_id      = "amazon_linux_2"
+  bundle_id         = "nano_3_0"
+
+  tags = {
+    Name      = "tf-test",
+    ExtraName = "tf-test"
+    EmptyTag1 = "NotEmptyAnymore"
+    EmptyTag2 = ""
+  }
+}
+`, rName))
+}
+
 func testAccInstanceConfig_IPAddressType(rName string, rIPAddressType string) string {
 	return acctest.ConfigCompose(
 		testAccInstanceConfigBase(),

internal/service/lightsail/tags.go

@@ -0,0 +1,50 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
+//go:build !generate
+// +build !generate
+
+package lightsail
+
+import (
+	"context"
+
+	"github.com/aws/aws-sdk-go-v2/service/lightsail"
+	"github.com/hashicorp/terraform-provider-aws/internal/conns"
+	tftags "github.com/hashicorp/terraform-provider-aws/internal/tags"
+	"github.com/hashicorp/terraform-provider-aws/internal/types/option"
+)
+
+func (p *servicePackage) ListTags(ctx context.Context, meta any, identifier, resourceType string) error {
+	var (
+		tags tftags.KeyValueTags
+		err  error
+	)
+	switch resourceType {
+	case "Instance":
+		tags, err = instanceListTags(ctx, meta.(*conns.AWSClient).LightsailClient(ctx), identifier)
+
+	default:
+		return nil
+	}
+
+	if err != nil {
+		return err
+	}
+
+	if inContext, ok := tftags.FromContext(ctx); ok {
+		inContext.TagsOut = option.Some(tags)
+	}
+
+	return nil
+}
+
+func instanceListTags(ctx context.Context, client *lightsail.Client, id string) (tftags.KeyValueTags, error) {
+	out, err := FindInstanceById(ctx, client, id)
+
+	if err != nil {
+		return tftags.New(ctx, nil), err
+	}
+
+	return KeyValueTags(ctx, out.Tags), nil
+}

internal/tags/key_value_tags.go

@@ -735,7 +735,11 @@ func (tags KeyValueTags) ResolveDuplicates(ctx context.Context, defaultConfig *D
 
 	result := make(map[string]string)
 	for k, v := range t {
-		result[k] = v.ValueString()
+		if v != nil {
+			result[k] = v.ValueString()
+		} else {
+			result[k] = ""
+		}
 	}
 
 	configTags := make(map[string]configTag)

internal/tags/key_value_tags_test.go

@@ -1433,6 +1433,15 @@ func TestKeyValueTagsMap(t *testing.T) {
 				"key3": "value3",
 			},
 		},
+		{
+			name: "empty_value",
+			tags: New(ctx, map[string]*string{
+				"key1": testStringPtr(""),
+			}),
+			want: map[string]string{
+				"key1": "",
+			},
+		},
 		{
 			name: "nil_value",
 			tags: New(ctx, map[string]*string{