Add support for aws_subnet_ids as a data source

builtin/providers/aws/data_source_aws_subnet_ids.go

@@ -0,0 +1,60 @@
+package aws
+
+import (
+	"fmt"
+	"log"
+
+	"github.com/aws/aws-sdk-go/service/ec2"
+	"github.com/hashicorp/terraform/helper/schema"
+)
+
+func dataSourceAwsSubnetIDs() *schema.Resource {
+	return &schema.Resource{
+		Read: dataSourceAwsSubnetIDsRead,
+		Schema: map[string]*schema.Schema{
+			"vpc_id": &schema.Schema{
+				Type:     schema.TypeString,
+				Required: true,
+			},
+			"ids": &schema.Schema{
+				Type:     schema.TypeSet,
+				Computed: true,
+				Elem:     &schema.Schema{Type: schema.TypeString},
+				Set:      schema.HashString,
+			},
+		},
+	}
+}
+
+func dataSourceAwsSubnetIDsRead(d *schema.ResourceData, meta interface{}) error {
+	conn := meta.(*AWSClient).ec2conn
+
+	req := &ec2.DescribeSubnetsInput{}
+
+	req.Filters = buildEC2AttributeFilterList(
+		map[string]string{
+			"vpc-id": d.Get("vpc_id").(string),
+		},
+	)
+
+	log.Printf("[DEBUG] DescribeSubnets %s\n", req)
+	resp, err := conn.DescribeSubnets(req)
+	if err != nil {
+		return err
+	}
+
+	if resp == nil || len(resp.Subnets) == 0 {
+		return fmt.Errorf("no matching subnet found for vpc with id %s", d.Get("vpc_id").(string))
+	}
+
+	subnets := make([]string, 0)
+
+	for _, subnet := range resp.Subnets {
+		subnets = append(subnets, *subnet.SubnetId)
+	}
+
+	d.SetId(d.Get("vpc_id").(string))
+	d.Set("ids", subnets)
+
+	return nil
+}

builtin/providers/aws/data_source_aws_subnet_ids_test.go

@@ -0,0 +1,79 @@
+package aws
+
+import (
+	"fmt"
+	"testing"
+
+	"github.com/hashicorp/terraform/helper/resource"
+	"github.com/hashicorp/terraform/terraform"
+)
+
+func TestAccDataSourceAwsSubnetIDs(t *testing.T) {
+	resource.Test(t, resource.TestCase{
+		PreCheck:  func() { testAccPreCheck(t) },
+		Providers: testAccProviders,
+		Steps: []resource.TestStep{
+			resource.TestStep{
+				Config: testAccDataSourceAwsSubnetIDsConfig,
+				Check: resource.ComposeTestCheckFunc(
+					testAccDataSourceAwsSubnetIDsCheck("data.aws_subnet_ids.selected"),
+				),
+			},
+		},
+	})
+}
+
+func testAccDataSourceAwsSubnetIDsCheck(name string) resource.TestCheckFunc {
+	return func(s *terraform.State) error {
+		rs, ok := s.RootModule().Resources[name]
+		if !ok {
+			return fmt.Errorf("root module has no resource called %s", name)
+		}
+
+		vpcRs, ok := s.RootModule().Resources["aws_vpc.test"]
+		if !ok {
+			return fmt.Errorf("can't find aws_vpc.test in state")
+		}
+		_, ok = s.RootModule().Resources["aws_subnet.test"]
+		if !ok {
+			return fmt.Errorf("can't find aws_subnet.test in state")
+		}
+
+		attr := rs.Primary.Attributes
+
+		if rs.Primary.ID != vpcRs.Primary.ID {
+			return fmt.Errorf("ID of this resource should be the vpc id")
+		}
+
+		return nil
+	}
+}
+
+const testAccDataSourceAwsSubnetIDsConfig = `
+provider "aws" {
+  region = "us-west-2"
+}
+
+resource "aws_vpc" "test" {
+  cidr_block = "172.16.0.0/16"
+
+  tags {
+    Name = "terraform-testacc-subnet-ids-data-source"
+  }
+}
+
+resource "aws_subnet" "test" {
+  vpc_id            = "${aws_vpc.test.id}"
+  cidr_block        = "172.16.123.0/24"
+  availability_zone = "us-west-2a"
+
+  tags {
+    Name = "terraform-testacc-subnet-ids-data-source"
+  }
+}
+
+data "aws_subnet_ids" "selected" {
+  vpc_id = "${aws_vpc.test.id}"
+  depends_on = ["aws_subnet.test"]
+}
+`

builtin/providers/aws/provider.go

@@ -188,6 +188,7 @@ func Provider() terraform.ResourceProvider {
 			"aws_s3_bucket_object":         dataSourceAwsS3BucketObject(),
 			"aws_sns_topic":                dataSourceAwsSnsTopic(),
 			"aws_subnet":                   dataSourceAwsSubnet(),
+			"aws_subnet_ids":               dataSourceAwsSubnetIDs(),
 			"aws_security_group":           dataSourceAwsSecurityGroup(),
 			"aws_vpc":                      dataSourceAwsVpc(),
 			"aws_vpc_endpoint":             dataSourceAwsVpcEndpoint(),