resource/rds_cluster_instance: Support availability_zone (#2812)

* Support availability_zone

* Add test

* Use aws_availability_zones

* Update

aws/resource_aws_rds_cluster_instance.go

@@ -176,6 +176,8 @@ func resourceAwsRDSClusterInstance() *schema.Resource {
 
 			"availability_zone": {
 				Type:     schema.TypeString,
+				Optional: true,
+				ForceNew: true,
 				Computed: true,
 			},
 
@@ -211,6 +213,10 @@ func resourceAwsRDSClusterInstanceCreate(d *schema.ResourceData, meta interface{
 		Tags: tags,
 	}
 
+	if attr, ok := d.GetOk("availability_zone"); ok {
+		createOpts.AvailabilityZone = aws.String(attr.(string))
+	}
+
 	if attr, ok := d.GetOk("db_parameter_group_name"); ok {
 		createOpts.DBParameterGroupName = aws.String(attr.(string))
 	}

aws/resource_aws_rds_cluster_instance_test.go

@@ -50,6 +50,26 @@ func TestAccAWSRDSClusterInstance_basic(t *testing.T) {
 	})
 }
 
+func TestAccAWSRDSClusterInstance_az(t *testing.T) {
+	var v rds.DBInstance
+
+	resource.Test(t, resource.TestCase{
+		PreCheck:     func() { testAccPreCheck(t) },
+		Providers:    testAccProviders,
+		CheckDestroy: testAccCheckAWSClusterDestroy,
+		Steps: []resource.TestStep{
+			{
+				Config: testAccAWSClusterInstanceConfig_az(acctest.RandInt()),
+				Check: resource.ComposeTestCheckFunc(
+					testAccCheckAWSClusterInstanceExists("aws_rds_cluster_instance.cluster_instances", &v),
+					testAccCheckAWSDBClusterInstanceAttributes(&v),
+					resource.TestMatchResourceAttr("aws_rds_cluster_instance.cluster_instances", "availability_zone", regexp.MustCompile("^us-west-2[a-z]{1}$")),
+				),
+			},
+		},
+	})
+}
+
 func TestAccAWSRDSClusterInstance_namePrefix(t *testing.T) {
 	var v rds.DBInstance
 	rInt := acctest.RandInt()
@@ -329,6 +349,45 @@ resource "aws_db_parameter_group" "bar" {
 `, n, n, n)
 }
 
+func testAccAWSClusterInstanceConfig_az(n int) string {
+	return fmt.Sprintf(`
+data "aws_availability_zones" "available" {}
+
+resource "aws_rds_cluster" "default" {
+  cluster_identifier = "tf-aurora-cluster-test-%d"
+  availability_zones = ["${data.aws_availability_zones.available.names}"]
+  database_name      = "mydb"
+  master_username    = "foo"
+  master_password    = "mustbeeightcharaters"
+  skip_final_snapshot = true
+}
+
+resource "aws_rds_cluster_instance" "cluster_instances" {
+  identifier              = "tf-cluster-instance-%d"
+  cluster_identifier      = "${aws_rds_cluster.default.id}"
+  instance_class          = "db.t2.small"
+  db_parameter_group_name = "${aws_db_parameter_group.bar.name}"
+  promotion_tier          = "3"
+  availability_zone       = "${data.aws_availability_zones.available.names[0]}"
+}
+
+resource "aws_db_parameter_group" "bar" {
+  name   = "tfcluster-test-group-%d"
+  family = "aurora5.6"
+
+  parameter {
+    name         = "back_log"
+    value        = "32767"
+    apply_method = "pending-reboot"
+  }
+
+  tags {
+    foo = "bar"
+  }
+}
+`, n, n, n)
+}
+
 func testAccAWSClusterInstanceConfig_namePrefix(n int) string {
 	return fmt.Sprintf(`
 resource "aws_rds_cluster_instance" "test" {

website/docs/r/rds_cluster_instance.html.markdown

@@ -73,7 +73,8 @@ details on controlling this property.
 enhanced monitoring metrics to CloudWatch Logs. You can find more information on the [AWS Documentation](http://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/USER_Monitoring.html)
 what IAM permissions are needed to allow Enhanced Monitoring for RDS Instances.
 * `monitoring_interval` - (Optional) The interval, in seconds, between points when Enhanced Monitoring metrics are collected for the DB instance. To disable collecting Enhanced Monitoring metrics, specify 0. The default is 0. Valid Values: 0, 1, 5, 10, 15, 30, 60.
-* `promotion_tier` - (Optional) Default 0. Failover Priority setting on instance level. The reader who has lower tier has higher priority to get promoter to writer. 
+* `promotion_tier` - (Optional) Default 0. Failover Priority setting on instance level. The reader who has lower tier has higher priority to get promoter to writer.
+* `availability_zone` - (Optional, Computed) The EC2 Availability Zone that the DB instance is created in. See [docs](https://docs.aws.amazon.com/AmazonRDS/latest/APIReference/API_CreateDBInstance.html) about the details.
 * `preferred_backup_window` - (Optional) The daily time range during which automated backups are created if automated backups are enabled.
   Eg: "04:00-09:00"
 * `preferred_maintenance_window` - (Optional) The window to perform maintenance in.