provider/aws: Add aws_availability_zones source

This commit adds a data source with a single list, `instance` for the
schema which gets populated with the availability zones to which an
account has access.

builtin/providers/aws/data_source_availability_zones.go

@@ -0,0 +1,52 @@
+package aws
+
+import (
+	"fmt"
+	"log"
+	"sort"
+	"time"
+
+	"github.com/aws/aws-sdk-go/aws"
+	"github.com/aws/aws-sdk-go/service/ec2"
+	"github.com/hashicorp/terraform/helper/schema"
+)
+
+func dataSourceAwsAvailabilityZones() *schema.Resource {
+	return &schema.Resource{
+		Read: dataSourceAwsAvailabilityZonesRead,
+
+		Schema: map[string]*schema.Schema{
+			"instance": &schema.Schema{
+				Type:     schema.TypeList,
+				Computed: true,
+				Elem:     &schema.Schema{Type: schema.TypeString},
+			},
+		},
+	}
+}
+
+func dataSourceAwsAvailabilityZonesRead(d *schema.ResourceData, meta interface{}) error {
+	conn := meta.(*AWSClient).ec2conn
+
+	log.Printf("[DEBUG] Reading availability zones")
+	d.SetId(time.Now().UTC().String())
+
+	req := &ec2.DescribeAvailabilityZonesInput{DryRun: aws.Bool(false)}
+	azresp, err := conn.DescribeAvailabilityZones(req)
+	if err != nil {
+		return fmt.Errorf("Error listing availability zones: %s", err)
+	}
+
+	raw := make([]string, len(azresp.AvailabilityZones))
+	for i, v := range azresp.AvailabilityZones {
+		raw[i] = *v.ZoneName
+	}
+
+	sort.Strings(raw)
+
+	if err := d.Set("instance", raw); err != nil {
+		return fmt.Errorf("[WARN] Error setting availability zones")
+	}
+
+	return nil
+}

builtin/providers/aws/provider.go

@@ -110,6 +110,10 @@ func Provider() terraform.ResourceProvider {
 			},
 		},
 
+		DataSourcesMap: map[string]*schema.Resource{
+			"aws_availability_zones": dataSourceAwsAvailabilityZones(),
+		},
+
 		ResourcesMap: map[string]*schema.Resource{
 			"aws_ami":                                      resourceAwsAmi(),
 			"aws_ami_copy":                                 resourceAwsAmiCopy(),

website/source/docs/providers/aws/d/availability_zones.html.markdown

@@ -0,0 +1,39 @@
+---
+layout: "aws"
+page_title: "AWS: aws_availability_zones"
+sidebar_current: "docs-aws-datasource-availability-zones"
+description: |-
+    Provides a list of availability zones which can be used by an AWS account
+---
+
+# aws\_availability\_zones
+
+The Availability Zones data source allows access to the list of AWS
+Availability Zones which can be accessed by an AWS account within the region
+configured in the provider.
+
+## Example Usage
+
+```
+# Declare the data source
+data "aws_availability_zones" "zones" {}
+
+# Create a subnet in each availability zone
+resource "aws_subnet" "public" {
+    count = "${length(data.aws_availability_zones.zones.instance)}"
+    
+    availability_zone = "${data.aws_availability_zones.zones.instance[count.index]}"
+
+    # Other properties...
+}
+```
+
+## Argument Reference
+
+There are no arguments for this data source.
+
+## Attributes Reference
+
+The following attributes are exported:
+
+* `instance` - A list of the availability zone names available to the account.

website/source/layouts/aws.erb

@@ -10,6 +10,15 @@
                     <a href="/docs/providers/aws/index.html">AWS Provider</a>
                 </li>
 
+                <li<%= sidebar_current(/^docs-aws-datasource/) %>
+                <a href="#">Data Sources</a>
+                    <ul class="nav nav-visible">
+                        <li<%= sidebar_current("docs-aws-datasource-availability-zones") %>>
+                            <a href="/docs/providers/aws/d/availability_zones.html">aws_availability_zones</a>
+                        </li>
+                    </ul>
+                </li>
+
                 <li<%= sidebar_current(/^docs-aws-resource-api-gateway/) %>>
                     <a href="#">API Gateway Resources</a>
                     <ul class="nav nav-visible">