resource azurerm_dns_zone: Add option to re-use host_name with dns_zone with soa_record creation

internal/services/dns/dns_zone_resource.go

@@ -5,6 +5,7 @@ import (
 	"strings"
 	"time"
 
+	"github.com/hashicorp/go-azure-helpers/lang/pointer"
 	"github.com/hashicorp/go-azure-helpers/lang/response"
 	"github.com/hashicorp/go-azure-helpers/resourcemanager/commonschema"
 	"github.com/hashicorp/go-azure-helpers/resourcemanager/location"
@@ -13,6 +14,7 @@ import (
 	"github.com/hashicorp/go-azure-sdk/resource-manager/dns/2018-05-01/zones"
 	"github.com/hashicorp/terraform-provider-azurerm/helpers/tf"
 	"github.com/hashicorp/terraform-provider-azurerm/internal/clients"
+	"github.com/hashicorp/terraform-provider-azurerm/internal/features"
 	"github.com/hashicorp/terraform-provider-azurerm/internal/services/dns/migration"
 	"github.com/hashicorp/terraform-provider-azurerm/internal/services/dns/validate"
 	"github.com/hashicorp/terraform-provider-azurerm/internal/tf/pluginsdk"
@@ -76,7 +78,7 @@ func resourceDnsZone() *pluginsdk.Resource {
 				MaxItems: 1,
 				Optional: true,
 				Computed: true,
-				ForceNew: true,
+				//ForceNew: true,
 				Elem: &pluginsdk.Resource{
 					Schema: map[string]*pluginsdk.Schema{
 						"email": {
@@ -86,9 +88,9 @@ func resourceDnsZone() *pluginsdk.Resource {
 						},
 
 						"host_name": {
-							Type:         pluginsdk.TypeString,
-							Required:     true,
-							ValidateFunc: validation.StringIsNotEmpty,
+							Type:     pluginsdk.TypeString,
+							Optional: !features.FourPointOhBeta(), // (@jackofallops) - This should not be set or updatable to meet API design, see https://learn.microsoft.com/en-us/azure/dns/dns-zones-records#soa-records
+							Computed: true,
 						},
 
 						"expire_time": {
@@ -182,11 +184,27 @@ func resourceDnsZoneCreateUpdate(d *pluginsdk.ResourceData, meta interface{}) er
 
 	if v, ok := d.GetOk("soa_record"); ok {
 		soaRecord := v.([]interface{})[0].(map[string]interface{})
+
+		soaRecordID := recordsets.NewRecordTypeID(id.SubscriptionId, id.ResourceGroupName, id.DnsZoneName, recordsets.RecordTypeSOA, "@")
+		soaRecordResp, err := recordSetsClient.Get(ctx, soaRecordID)
+		if err != nil {
+			return fmt.Errorf("retrieving %s to update SOA: %+v", id, err)
+		}
+
+		props := soaRecordResp.Model.Properties
+		if props == nil || props.SOARecord == nil {
+			return fmt.Errorf("could not read SOA properties for %s", id)
+		}
+
+		inputSOARecord := expandArmDNSZoneSOARecord(soaRecord)
+
+		inputSOARecord.Host = props.SOARecord.Host
+
 		rsParameters := recordsets.RecordSet{
 			Properties: &recordsets.RecordSetProperties{
 				TTL:       utils.Int64(int64(soaRecord["ttl"].(int))),
 				Metadata:  tags.Expand(soaRecord["tags"].(map[string]interface{})),
-				SOARecord: expandArmDNSZoneSOARecord(soaRecord),
+				SOARecord: inputSOARecord,
 			},
 		}
 
@@ -278,15 +296,20 @@ func resourceDnsZoneDelete(d *pluginsdk.ResourceData, meta interface{}) error {
 }
 
 func expandArmDNSZoneSOARecord(input map[string]interface{}) *recordsets.SoaRecord {
-	return &recordsets.SoaRecord{
+	result := &recordsets.SoaRecord{
 		Email:        utils.String(input["email"].(string)),
-		Host:         utils.String(input["host_name"].(string)),
 		ExpireTime:   utils.Int64(int64(input["expire_time"].(int))),
 		MinimumTTL:   utils.Int64(int64(input["minimum_ttl"].(int))),
 		RefreshTime:  utils.Int64(int64(input["refresh_time"].(int))),
 		RetryTime:    utils.Int64(int64(input["retry_time"].(int))),
 		SerialNumber: utils.Int64(int64(input["serial_number"].(int))),
 	}
+
+	if !features.FourPointOhBeta() && input["host_name"].(string) != "" {
+		result.Host = pointer.To(input["host_name"].(string))
+	}
+
+	return result
 }
 
 func flattenArmDNSZoneSOARecord(input *recordsets.RecordSet) []interface{} {

internal/services/dns/dns_zone_resource_test.go

@@ -71,7 +71,7 @@ func TestAccDnsZone_withTags(t *testing.T) {
 	})
 }
 
-func TestAccDnsZone_withSOARecord(t *testing.T) {
+func TestAccDnsZone_basicSOARecord(t *testing.T) {
 	data := acceptance.BuildTestData(t, "azurerm_dns_zone", "test")
 	r := DnsZoneResource{}
 
@@ -83,6 +83,43 @@ func TestAccDnsZone_withSOARecord(t *testing.T) {
 			),
 		},
 		data.ImportStep(),
+	})
+}
+
+func TestAccDnsZone_completeSOARecord(t *testing.T) {
+	data := acceptance.BuildTestData(t, "azurerm_dns_zone", "test")
+	r := DnsZoneResource{}
+
+	data.ResourceTest(t, r, []acceptance.TestStep{
+		{
+			Config: r.withCompletedSOARecord(data),
+			Check: acceptance.ComposeTestCheckFunc(
+				check.That(data.ResourceName).ExistsInAzure(r),
+			),
+		},
+		data.ImportStep(),
+	})
+}
+
+func TestAccDnsZone_updateSOARecord(t *testing.T) {
+	data := acceptance.BuildTestData(t, "azurerm_dns_zone", "test")
+	r := DnsZoneResource{}
+
+	data.ResourceTest(t, r, []acceptance.TestStep{
+		{
+			Config: r.basic(data),
+			Check: acceptance.ComposeTestCheckFunc(
+				check.That(data.ResourceName).ExistsInAzure(r),
+			),
+		},
+		data.ImportStep(),
+		{
+			Config: r.withBasicSOARecord(data),
+			Check: acceptance.ComposeTestCheckFunc(
+				check.That(data.ResourceName).ExistsInAzure(r),
+			),
+		},
+		data.ImportStep(),
 		{
 			Config: r.withCompletedSOARecord(data),
 			Check: acceptance.ComposeTestCheckFunc(
@@ -205,8 +242,7 @@ resource "azurerm_dns_zone" "test" {
   resource_group_name = azurerm_resource_group.test.name
 
   soa_record {
-    email     = "testemail.com"
-    host_name = "testhost.contoso.com"
+    email = "testemail.com"
   }
 }
 `, data.RandomInteger, data.Locations.Primary, data.RandomInteger)
@@ -229,7 +265,6 @@ resource "azurerm_dns_zone" "test" {
 
   soa_record {
     email         = "testemail.com"
-    host_name     = "testhost.contoso.com"
     expire_time   = 2419200
     minimum_ttl   = 200
     refresh_time  = 2600

website/docs/r/dns_zone.html.markdown

@@ -42,7 +42,7 @@ The `soa_record` block supports:
 
 * `email` - (Required) The email contact for the SOA record.
 
-* `host_name` - (Required) The domain name of the authoritative name server for the SOA record.
+* `host_name` - (Optional) The domain name of the authoritative name server for the SOA record. If not set, computed value from Azure will be used.
 
 * `expire_time` - (Optional) The expire time for the SOA record. Defaults to `2419200`.