resource/aws_eks_node_group: Only pass ReleaseVersion during UpdateNo…

…degroupVersion if changed (hashicorp#13407)

Reference: hashicorp#12675

It was expected to see an error similar to the issue report about the incompatible update and Terraform was previously submitting the state value for `release_version`, however the EKS API as of today was automatically fixing the incorrect value instead of returning an error. The resource change is to ensure that we will only submit correct API parameters should the API return errors for this situation in the future again.

Output from acceptance testing:

```
--- PASS: TestAccAWSEksNodeGroup_disappears (1356.93s)
--- PASS: TestAccAWSEksNodeGroup_InstanceTypes (1519.46s)
--- PASS: TestAccAWSEksNodeGroup_ScalingConfig_MaxSize (1540.56s)
--- PASS: TestAccAWSEksNodeGroup_DiskSize (1550.40s)
--- PASS: TestAccAWSEksNodeGroup_basic (1581.83s)
--- PASS: TestAccAWSEksNodeGroup_AmiType (1591.47s)
--- PASS: TestAccAWSEksNodeGroup_RemoteAccess_SourceSecurityGroupIds (1602.60s)
--- PASS: TestAccAWSEksNodeGroup_ScalingConfig_DesiredSize (1632.41s)
--- PASS: TestAccAWSEksNodeGroup_ScalingConfig_MinSize (1683.52s)
--- PASS: TestAccAWSEksNodeGroup_Tags (1712.30s)
--- PASS: TestAccAWSEksNodeGroup_Labels (1765.19s)
--- PASS: TestAccAWSEksNodeGroup_RemoteAccess_Ec2SshKey (1767.20s)
--- PASS: TestAccAWSEksNodeGroup_ReleaseVersion (2853.92s)
--- PASS: TestAccAWSEksNodeGroup_Version (3045.62s)
```

aws/resource_aws_eks_node_group.go

@@ -377,7 +377,7 @@ func resourceAwsEksNodeGroupUpdate(d *schema.ResourceData, meta interface{}) err
 			NodegroupName:      aws.String(nodeGroupName),
 		}
 
-		if v, ok := d.GetOk("release_version"); ok {
+		if v, ok := d.GetOk("release_version"); ok && d.HasChange("release_version") {
 			input.ReleaseVersion = aws.String(v.(string))
 		}
 

aws/resource_aws_eks_node_group_test.go

@@ -280,7 +280,7 @@ func TestAccAWSEksNodeGroup_ReleaseVersion(t *testing.T) {
 		CheckDestroy: testAccCheckAWSEksNodeGroupDestroy,
 		Steps: []resource.TestStep{
 			{
-				Config: testAccAWSEksNodeGroupConfigReleaseVersion(rName),
+				Config: testAccAWSEksNodeGroupConfigReleaseVersion(rName, "1.15"),
 				Check: resource.ComposeTestCheckFunc(
 					testAccCheckAWSEksNodeGroupExists(resourceName, &nodeGroup1),
 					resource.TestCheckResourceAttrPair(resourceName, "release_version", ssmParameterDataSourceName, "value"),
@@ -291,6 +291,13 @@ func TestAccAWSEksNodeGroup_ReleaseVersion(t *testing.T) {
 				ImportState:       true,
 				ImportStateVerify: true,
 			},
+			{
+				Config: testAccAWSEksNodeGroupConfigReleaseVersion(rName, "1.16"),
+				Check: resource.ComposeTestCheckFunc(
+					testAccCheckAWSEksNodeGroupExists(resourceName, &nodeGroup1),
+					resource.TestCheckResourceAttrPair(resourceName, "release_version", ssmParameterDataSourceName, "value"),
+				),
+			},
 		},
 	})
 }
@@ -521,17 +528,24 @@ func TestAccAWSEksNodeGroup_Version(t *testing.T) {
 		CheckDestroy: testAccCheckAWSEksNodeGroupDestroy,
 		Steps: []resource.TestStep{
 			{
-				Config: testAccAWSEksNodeGroupConfigVersion(rName, "1.14"),
+				Config: testAccAWSEksNodeGroupConfigVersion(rName, "1.15"),
 				Check: resource.ComposeTestCheckFunc(
 					testAccCheckAWSEksNodeGroupExists(resourceName, &nodeGroup1),
-					resource.TestCheckResourceAttr(resourceName, "version", "1.14"),
+					resource.TestCheckResourceAttr(resourceName, "version", "1.15"),
 				),
 			},
 			{
 				ResourceName:      resourceName,
 				ImportState:       true,
 				ImportStateVerify: true,
 			},
+			{
+				Config: testAccAWSEksNodeGroupConfigVersion(rName, "1.16"),
+				Check: resource.ComposeTestCheckFunc(
+					testAccCheckAWSEksNodeGroupExists(resourceName, &nodeGroup1),
+					resource.TestCheckResourceAttr(resourceName, "version", "1.16"),
+				),
+			},
 		},
 	})
 }
@@ -961,8 +975,8 @@ resource "aws_eks_node_group" "test" {
 `, rName, labelKey1, labelValue1, labelKey2, labelValue2)
 }
 
-func testAccAWSEksNodeGroupConfigReleaseVersion(rName string) string {
-	return testAccAWSEksNodeGroupConfigBase(rName) + fmt.Sprintf(`
+func testAccAWSEksNodeGroupConfigReleaseVersion(rName string, version string) string {
+	return testAccAWSEksNodeGroupConfigBaseVersion(rName, version) + fmt.Sprintf(`
 data "aws_ssm_parameter" "test" {
   name = "/aws/service/eks/optimized-ami/${aws_eks_cluster.test.version}/amazon-linux-2/recommended/release_version"
 }
@@ -973,6 +987,7 @@ resource "aws_eks_node_group" "test" {
   node_role_arn   = aws_iam_role.node.arn
   release_version = data.aws_ssm_parameter.test.value
   subnet_ids      = aws_subnet.test[*].id
+  version         = aws_eks_cluster.test.version
 
   scaling_config {
     desired_size = 1