Merge pull request #359 from terraform-providers/paddy_95_dns_ns

dns: Add special handling for ns records.

google/resource_dns_record_set.go

@@ -77,6 +77,33 @@ func resourceDnsRecordSetCreate(d *schema.ResourceData, meta interface{}) error
 		},
 	}
 
+	// we need to replace NS record sets in the same call. That means
+	// we need to list all the current NS record sets attached to the
+	// zone and add them to the change as deletions. We can't just add
+	// new NS record sets, or we'll get an error about the NS record set
+	// already existing; see terraform-providers/terraform-provider-google#95.
+	// We also can't just remove the NS recordsets on creation, as at
+	// least one is required. So the solution is to "update in place" by
+	// putting the addition and the removal in the same API call.
+	if d.Get("type").(string) == "NS" {
+		log.Printf("[DEBUG] DNS record list request for %q", zone)
+		res, err := config.clientDns.ResourceRecordSets.List(project, zone).Do()
+		if err != nil {
+			return fmt.Errorf("Error retrieving record sets for %q: %s", zone, err)
+		}
+		var deletions []*dns.ResourceRecordSet
+
+		for _, record := range res.Rrsets {
+			if record.Type != "NS" {
+				continue
+			}
+			deletions = append(deletions, record)
+		}
+		if len(deletions) > 0 {
+			chg.Deletions = deletions
+		}
+	}
+
 	log.Printf("[DEBUG] DNS Record create request: %#v", chg)
 	chg, err = config.clientDns.Changes.Create(project, zone, chg).Do()
 	if err != nil {
@@ -135,6 +162,14 @@ func resourceDnsRecordSetRead(d *schema.ResourceData, meta interface{}) error {
 }
 
 func resourceDnsRecordSetDelete(d *schema.ResourceData, meta interface{}) error {
+
+	// NS records must always have a value, so we short-circuit delete
+	// this allows terraform delete to work, but may have unexpected
+	// side-effects when deleting just that record set.
+	if d.Get("type").(string) == "NS" {
+		log.Println("[DEBUG] NS records can't be deleted due to API restrictions, so they're being left in place. See https://www.terraform.io/docs/providers/google/r/dns_record_set.html for more information.")
+		return nil
+	}
 	config := meta.(*Config)
 
 	project, err := getProject(d, config)

google/resource_dns_record_set_test.go

@@ -90,6 +90,24 @@ func TestAccDnsRecordSet_changeType(t *testing.T) {
 	})
 }
 
+func TestAccDnsRecordSet_ns(t *testing.T) {
+	zoneName := fmt.Sprintf("dnszone-test-ns-%s", acctest.RandString(10))
+	resource.Test(t, resource.TestCase{
+		PreCheck:     func() { testAccPreCheck(t) },
+		Providers:    testAccProviders,
+		CheckDestroy: testAccCheckDnsRecordSetDestroy,
+		Steps: []resource.TestStep{
+			resource.TestStep{
+				Config: testAccDnsRecordSet_ns(zoneName, 300),
+				Check: resource.ComposeTestCheckFunc(
+					testAccCheckDnsRecordSetExists(
+						"google_dns_record_set.foobar", zoneName),
+				),
+			},
+		},
+	})
+}
+
 func testAccCheckDnsRecordSetDestroy(s *terraform.State) error {
 	config := testAccProvider.Meta().(*Config)
 
@@ -157,6 +175,23 @@ func testAccDnsRecordSet_basic(zoneName string, addr2 string, ttl int) string {
 	`, zoneName, addr2, ttl)
 }
 
+func testAccDnsRecordSet_ns(name string, ttl int) string {
+	return fmt.Sprintf(`
+	resource "google_dns_managed_zone" "parent-zone" {
+		name = "%s"
+		dns_name = "hashicorptest.com."
+		description = "Test Description"
+	}
+	resource "google_dns_record_set" "foobar" {
+		managed_zone = "${google_dns_managed_zone.parent-zone.name}"
+		name = "hashicorptest.com."
+		type = "NS"
+		rrdatas = ["ns.hashicorp.services.", "ns2.hashicorp.services."]
+		ttl = %d
+	}
+	`, name, ttl)
+}
+
 func testAccDnsRecordSet_bigChange(zoneName string, ttl int) string {
 	return fmt.Sprintf(`
 	resource "google_dns_managed_zone" "parent-zone" {

website/docs/r/dns_record_set.markdown

@@ -10,6 +10,12 @@ description: |-
 
 Manages a set of DNS records within Google Cloud DNS.
 
+~> **Note:** The Google Cloud DNS API requires NS records be present at all
+times. To accommodate this, when creating NS records, the default records
+Google automatically creates will be silently overwritten.  Also, when
+destroying NS records, Terraform will not actually remove NS records, but will
+report that it did.
+
 ## Example Usage
 
 ### Binding a DNS name to the ephemeral IP of a new instance: