data-source/aws_db_subnet_group: create aws_db_subnet_group data-source

Adds a data source for aws_db_subnet_group. Used aws_db_instance as a
model for this work. Currently only allows looking up exactly one
database subnet group using `name` as the argument, although the AWS RDS
API also supports using `filters`. Returns all of the attributes listed
on the AWS docs for the DBSubnetGroup data type. The `subnets` attribute
contains a list of subnet identifiers.

Resolves #3326

aws/data_source_aws_db_subnet_group.go

@@ -0,0 +1,93 @@
+package aws
+
+import (
+	"fmt"
+	"log"
+
+	"github.com/aws/aws-sdk-go/aws"
+	"github.com/aws/aws-sdk-go/service/rds"
+	"github.com/hashicorp/terraform/helper/schema"
+)
+
+func dataSourceAwsDbSubnetGroup() *schema.Resource {
+	return &schema.Resource{
+		Read: dataSourceAwsDbSubnetGroupRead,
+
+		Schema: map[string]*schema.Schema{
+			"arn": {
+				Type:     schema.TypeString,
+				Computed: true,
+			},
+
+			"description": {
+				Type:     schema.TypeString,
+				Computed: true,
+			},
+
+			"name": {
+				Type:     schema.TypeString,
+				Required: true,
+				ForceNew: true,
+			},
+
+			"status": {
+				Type:     schema.TypeString,
+				Computed: true,
+			},
+
+			"subnets": {
+				Type:     schema.TypeList,
+				Computed: true,
+				Elem:     &schema.Schema{Type: schema.TypeString},
+			},
+
+			"vpc_id": {
+				Type:     schema.TypeString,
+				Computed: true,
+			},
+		},
+	}
+}
+
+func dataSourceAwsDbSubnetGroupRead(d *schema.ResourceData, meta interface{}) error {
+	conn := meta.(*AWSClient).rdsconn
+
+	opts := &rds.DescribeDBSubnetGroupsInput{
+		DBSubnetGroupName: aws.String(d.Get("name").(string)),
+	}
+
+	log.Printf("[DEBUG] Reading DB SubnetGroup: %s", opts)
+
+	resp, err := conn.DescribeDBSubnetGroups(opts)
+	if err != nil {
+		return err
+	}
+
+	if len(resp.DBSubnetGroups) < 1 {
+		return fmt.Errorf("Your query returned no results. Please change your search criteria and try again.")
+	}
+	if len(resp.DBSubnetGroups) > 1 {
+		return fmt.Errorf("Your query returned more than one result. Please try a more specific search criteria.")
+	}
+
+	dbSubnetGroup := *resp.DBSubnetGroups[0]
+
+	d.SetId(d.Get("name").(string))
+
+	d.Set("arn", dbSubnetGroup.DBSubnetGroupArn)
+	d.Set("description", dbSubnetGroup.DBSubnetGroupDescription)
+	d.Set("name", dbSubnetGroup.DBSubnetGroupName)
+	d.Set("status", dbSubnetGroup.SubnetGroupStatus)
+
+	var subnets []string
+	for _, v := range dbSubnetGroup.Subnets {
+		subnets = append(subnets, *v.SubnetIdentifier)
+	}
+	if err := d.Set("subnets", subnets); err != nil {
+		return fmt.Errorf("Error setting subnets attribute: %#v, error: %#v", subnets, err)
+	}
+
+	d.Set("vpc_id", dbSubnetGroup.VpcId)
+
+	return nil
+}

aws/data_source_aws_db_subnet_group_test.go

@@ -0,0 +1,59 @@
+package aws
+
+import (
+	"fmt"
+	"testing"
+
+	"github.com/hashicorp/terraform/helper/acctest"
+	"github.com/hashicorp/terraform/helper/resource"
+)
+
+func TestAccAWSDbSubnetGroupDataSource_basic(t *testing.T) {
+	rInt := acctest.RandInt()
+	resource.ParallelTest(t, resource.TestCase{
+		PreCheck:  func() { testAccPreCheck(t) },
+		Providers: testAccProviders,
+		Steps: []resource.TestStep{
+			{
+				Config: testAccAWSDBSubnetGroupDataSourceConfig(rInt),
+				Check: resource.ComposeAggregateTestCheckFunc(
+					resource.TestCheckResourceAttrSet("data.aws_db_subnet_group.bar", "arn"),
+					resource.TestCheckResourceAttrSet("data.aws_db_subnet_group.bar", "description"),
+					resource.TestCheckResourceAttrSet("data.aws_db_subnet_group.bar", "name"),
+					resource.TestCheckResourceAttrSet("data.aws_db_subnet_group.bar", "status"),
+					resource.TestCheckResourceAttrSet("data.aws_db_subnet_group.bar", "subnets.0"),
+					resource.TestCheckResourceAttrSet("data.aws_db_subnet_group.bar", "subnets.1"),
+					resource.TestCheckResourceAttrSet("data.aws_db_subnet_group.bar", "vpc_id"),
+				),
+			},
+		},
+	})
+}
+
+func testAccAWSDBSubnetGroupDataSourceConfig(rInt int) string {
+	return fmt.Sprintf(`
+data "aws_availability_zones" "available" {
+  state = "available"
+}
+
+resource "aws_vpc" "foo" {
+  cidr_block = "10.0.0.0/16"
+}
+
+resource "aws_subnet" "foo" {
+  count             = 2
+  availability_zone = "${data.aws_availability_zones.available.names[count.index]}" 
+  cidr_block        = "10.0.${count.index}.0/24"
+  vpc_id            = "${aws_vpc.foo.id}"
+}
+
+resource "aws_db_subnet_group" "bar" {
+  name       = "datasource-test-terraform-%d"
+  subnet_ids = "${aws_subnet.foo.*.id}"
+}
+
+data "aws_db_subnet_group" "bar" {
+  name = "${aws_db_subnet_group.bar.name}"
+}
+`, rInt)
+}

aws/provider.go

@@ -171,6 +171,7 @@ func Provider() terraform.ResourceProvider {
 			"aws_db_event_categories":                       dataSourceAwsDbEventCategories(),
 			"aws_db_instance":                               dataSourceAwsDbInstance(),
 			"aws_db_snapshot":                               dataSourceAwsDbSnapshot(),
+			"aws_db_subnet_group":                           dataSourceAwsDbSubnetGroup(),
 			"aws_dx_gateway":                                dataSourceAwsDxGateway(),
 			"aws_dynamodb_table":                            dataSourceAwsDynamoDbTable(),
 			"aws_ebs_default_kms_key":                       dataSourceAwsEbsDefaultKmsKey(),

website/aws.erb

@@ -2258,6 +2258,9 @@
                                 <li>
                                     <a href="/docs/providers/aws/d/db_snapshot.html">aws_db_snapshot</a>
                                 </li>
+                                <li>
+                                    <a href="/docs/providers/aws/d/db_subnet_group.html">aws_db_subnet_group</a>
+                                </li>
                                 <li>
                                     <a href="/docs/providers/aws/d/rds_cluster.html">aws_rds_cluster</a>
                                 </li>

website/docs/d/db_subnet_group.html.markdown

@@ -0,0 +1,35 @@
+---
+layout: "aws"
+page_title: "AWS: aws_db_subnet_group"
+sidebar_current: "docs-aws-datasource-db-subnet-group"
+description: |-
+  Get information on an RDS Database Subnet Group.
+---
+
+# Data Source: aws_db_subnet_group
+
+Use this data source to get information about an RDS subnet group
+
+## Example Usage
+
+```hcl
+data "aws_db_subnet_group" "database" {
+  name = "my-test-database-subnet-group"
+}
+```
+
+## Argument Reference
+
+The following arguments are supported:
+
+* `name` - (Required) The name of the RDS database subnet group
+
+## Attributes Reference
+
+In addition to all arguments above, the following attributes are exported:
+
+* `arn` - The Amazon Resource Name (ARN) for the DB subnet group..
+* `description` - Provides the description of the DB subnet group.
+* `status` - Provides the status of the DB subnet group.
+* `subnets` - Contains a list of subnet identifiers.
+* `vpc_id` - Provides the VPC ID of the subnet group.