provider/aws: aws_region data source

The primary purpose of this data source is to ask the question "what is
my current region?", but it can also be used to retrieve the endpoint
hostname for a particular (possibly non-current) region, should that be
useful for some esoteric case.

builtin/providers/aws/data_source_aws_region.go

@@ -0,0 +1,78 @@
+package aws
+
+import (
+	"fmt"
+	"log"
+
+	"github.com/aws/aws-sdk-go/aws"
+	"github.com/aws/aws-sdk-go/service/ec2"
+	"github.com/hashicorp/terraform/helper/schema"
+)
+
+func dataSourceAwsRegion() *schema.Resource {
+	return &schema.Resource{
+		Read: dataSourceAwsRegionRead,
+
+		Schema: map[string]*schema.Schema{
+			"name": &schema.Schema{
+				Type:     schema.TypeString,
+				Optional: true,
+				Computed: true,
+			},
+
+			"current": &schema.Schema{
+				Type:     schema.TypeBool,
+				Optional: true,
+				Computed: true,
+			},
+
+			"endpoint": &schema.Schema{
+				Type:     schema.TypeString,
+				Optional: true,
+				Computed: true,
+			},
+		},
+	}
+}
+
+func dataSourceAwsRegionRead(d *schema.ResourceData, meta interface{}) error {
+	conn := meta.(*AWSClient).ec2conn
+	currentRegion := meta.(*AWSClient).region
+
+	req := &ec2.DescribeRegionsInput{}
+
+	req.RegionNames = make([]*string, 0, 2)
+	if name := d.Get("name").(string); name != "" {
+		req.RegionNames = append(req.RegionNames, aws.String(name))
+	}
+
+	if d.Get("current").(bool) {
+		req.RegionNames = append(req.RegionNames, aws.String(currentRegion))
+	}
+
+	req.Filters = buildEC2FilterList(d, map[string]string{
+		"endpoint": "endpoint",
+	})
+
+	log.Printf("[DEBUG] DescribeRegions %#v\n", req)
+	resp, err := conn.DescribeRegions(req)
+	if err != nil {
+		return err
+	}
+	if resp == nil || len(resp.Regions) == 0 {
+		return fmt.Errorf("no matching regions found")
+	}
+	if len(resp.Regions) > 1 {
+		return fmt.Errorf("multiple regions matched; use additional constraints to reduce matches to a single region")
+	}
+
+	region := resp.Regions[0]
+
+	d.SetId(*region.RegionName)
+	d.Set("id", region.RegionName)
+	d.Set("name", region.RegionName)
+	d.Set("endpoint", region.Endpoint)
+	d.Set("current", *region.RegionName == currentRegion)
+
+	return nil
+}

builtin/providers/aws/provider.go

@@ -113,6 +113,7 @@ func Provider() terraform.ResourceProvider {
 		DataSourcesMap: map[string]*schema.Resource{
 			"aws_availability_zone":  dataSourceAwsAvailabilityZone(),
 			"aws_availability_zones": dataSourceAwsAvailabilityZones(),
+			"aws_region":             dataSourceAwsRegion(),
 			"aws_subnet":             dataSourceAwsSubnet(),
 			"aws_vpc":                dataSourceAwsVpc(),
 		},