providers/aws: fix tests for subnet map_public_ip, add docs

This working depends on merging mitchellh/goamz#109

Related: #285

cc/ @hden

builtin/providers/aws/resource_aws_subnet.go

@@ -55,12 +55,10 @@ func resource_aws_subnet_create(
 			s.ID, err)
 	}
 
-	var attr string
-
 	// Map public ip on launch must be set in another API call
-	if attr = s.Attributes["map_public_ip_on_launch"]; attr == "true" {
+	if attr := s.Attributes["map_public_ip_on_launch"]; attr == "true" {
 		modifyOpts := &ec2.ModifySubnetAttribute{
-			SubnetId: s.ID,
+			SubnetId:            s.ID,
 			MapPublicIpOnLaunch: true,
 		}
 		log.Printf("[DEBUG] Subnet modify attributes: %#v", modifyOpts)

builtin/providers/aws/resource_aws_subnet_test.go

@@ -20,7 +20,7 @@ func TestAccAWSSubnet(t *testing.T) {
 		if v.MapPublicIpOnLaunch != true {
 			return fmt.Errorf("bad MapPublicIpOnLaunch: %s", v.MapPublicIpOnLaunch)
 		}
-		return fmt.Errorf("bad MapPublicIpOnLaunch: %s", v.MapPublicIpOnLaunch)
+
 		return nil
 	}
 

website/source/docs/providers/aws/r/subnet.html.markdown

@@ -23,6 +23,9 @@ The following arguments are supported:
 
 * `availability_zone`- (Optional) The AZ for the subnet.
 * `cidr_block` - (Required) The CIDR block for the subnet.
+* `map_public_ip_on_launch` -  (Optional) Specify true to indicate
+    that instances launched into the subnet should be assigned
+    a public IP address.
 * `vpc_id` - (Required) The VPC ID.
 
 ## Attributes Reference