add disable_dns_servers option to subnet

cloudscale/resource_cloudscale_subnet.go

@@ -77,6 +77,12 @@
 			Type:     schema.TypeString,
 			Optional: true,
 		}
+	} else {
+		m["disable_dns_servers"] = &schema.Schema{
+			Type:          schema.TypeBool,
+			Optional:      true,
+			ConflictsWith: []string{"dns_servers"},
+		}
 	}
 	return m
 }
@@ -95,12 +101,22 @@
 		opts.GatewayAddress = attr.(string)
 	}
 
-	dnsServers := d.Get("dns_servers").([]any)
-	s := make([]string, len(dnsServers))
-	for i := range dnsServers {
-		s[i] = dnsServers[i].(string)
+	disableDnsServers := d.Get("disable_dns_servers").(bool)
+	if disableDnsServers {
+		opts.DNSServers = &[]string{}
+	} else {
+		if dnsServersRaw, ok := d.GetOk("dns_servers"); ok {
+			dnsServers := dnsServersRaw.([]interface{})
+			dnsServersStr := make([]string, len(dnsServers))
+			for i := range dnsServers {
+				dnsServersStr[i] = dnsServers[i].(string)
+			}
+			opts.DNSServers = &dnsServersStr
+		} else {
+			opts.DNSServers = &cloudscale.UseCloudscaleDefaults
+		}
 	}
-	opts.DNSServers = s
+
 	opts.Tags = CopyTags(d)
 
 	log.Printf("[DEBUG] Subnet create configuration: %#v", opts)
@@ -149,21 +165,30 @@
 func gatherSubnetUpdateRequests(d *schema.ResourceData) []*cloudscale.SubnetUpdateRequest {
 	requests := make([]*cloudscale.SubnetUpdateRequest, 0)
 
-	for _, attribute := range []string{"gateway_address", "dns_servers", "tags"} {
+	for _, attribute := range []string{"gateway_address", "dns_servers", "tags", "disable_dns_servers"} {
 		if d.HasChange(attribute) {
 			log.Printf("[INFO] Attribute %s changed", attribute)
 			opts := &cloudscale.SubnetUpdateRequest{}
 			requests = append(requests, opts)
 
 			if attribute == "gateway_address" {
 				opts.GatewayAddress = d.Get(attribute).(string)
-			} else if attribute == "dns_servers" {
-				dnsServers := d.Get("dns_servers").([]any)
-				s := make([]string, len(dnsServers))
-				for i := range dnsServers {
-					s[i] = dnsServers[i].(string)
+			} else if attribute == "dns_servers" || attribute == "disable_dns_servers" {
+				disableDnsServers := d.Get("disable_dns_servers").(bool)
+				if disableDnsServers {
+					opts.DNSServers = &[]string{}
+				} else {
+					if dnsServersRaw, ok := d.GetOk("dns_servers"); ok {
+						dnsServers := dnsServersRaw.([]interface{})
+						dnsServersStr := make([]string, len(dnsServers))
+						for i := range dnsServers {
+							dnsServersStr[i] = dnsServers[i].(string)
+						}
+						opts.DNSServers = &dnsServersStr
+					} else {
+						opts.DNSServers = &cloudscale.UseCloudscaleDefaults
+					}
 				}
-				opts.DNSServers = s
 			} else if attribute == "tags" {
 				opts.Tags = CopyTags(d)
 			}

cloudscale/resource_cloudscale_subnet_test.go

@@ -80,6 +80,35 @@ func TestAccCloudscaleSubnet_AllAttrs(t *testing.T) {
 	})
 }
 
+func TestAccCloudscaleSubnet_NoDNS_Create(t *testing.T) {
+	var subnet cloudscale.Subnet
+	var network cloudscale.Network
+
+	rInt := acctest.RandInt()
+
+	resource.ParallelTest(t, resource.TestCase{
+		PreCheck:     func() { testAccPreCheck(t) },
+		Providers:    testAccProviders,
+		CheckDestroy: testAccCheckCloudscaleSubnetDestroy,
+		Steps: []resource.TestStep{
+			{
+				Config: subnetconfigNoDns(rInt),
+				Check: resource.ComposeTestCheckFunc(
+					testAccCheckCloudscaleNetworkExists("cloudscale_network.basic", &network),
+					testAccCheckCloudscaleSubnetExists("cloudscale_subnet.basic", &subnet),
+					testAccCheckCloudscaleSubnetOnNetwork(&subnet, &network),
+					resource.TestCheckResourceAttr("cloudscale_subnet.basic", "cidr", "10.11.12.0/24"),
+					resource.TestCheckResourceAttrSet("cloudscale_subnet.basic", "network_href"),
+					resource.TestCheckResourceAttrSet("cloudscale_subnet.basic", "network_uuid"),
+					resource.TestCheckResourceAttr("cloudscale_subnet.basic", "network_name", fmt.Sprintf("terraform-%d", rInt)),
+					resource.TestCheckResourceAttr("cloudscale_subnet.basic", "gateway_address", "10.11.12.10"),
+					resource.TestCheckResourceAttr("cloudscale_subnet.basic", "dns_servers.#", "0"),
+				),
+			},
+		},
+	})
+}
+
 func TestAccCloudscaleSubnet_Update(t *testing.T) {
 	var subnet cloudscale.Subnet
 	var network cloudscale.Network
@@ -124,6 +153,20 @@ func TestAccCloudscaleSubnet_Update(t *testing.T) {
 					resource.TestCheckResourceAttr("cloudscale_subnet.basic", "dns_servers.2", "9.10.11.12"),
 				),
 			},
+			{
+				Config: subnetconfigNoDns(rInt),
+				Check: resource.ComposeTestCheckFunc(
+					testAccCheckCloudscaleNetworkExists("cloudscale_network.basic", &network),
+					testAccCheckCloudscaleSubnetExists("cloudscale_subnet.basic", &subnet),
+					testAccCheckCloudscaleSubnetOnNetwork(&subnet, &network),
+					resource.TestCheckResourceAttr("cloudscale_subnet.basic", "cidr", "10.11.12.0/24"),
+					resource.TestCheckResourceAttrSet("cloudscale_subnet.basic", "network_href"),
+					resource.TestCheckResourceAttrSet("cloudscale_subnet.basic", "network_uuid"),
+					resource.TestCheckResourceAttr("cloudscale_subnet.basic", "network_name", fmt.Sprintf("terraform-%d", rInt)),
+					resource.TestCheckResourceAttr("cloudscale_subnet.basic", "gateway_address", "10.11.12.10"),
+					resource.TestCheckResourceAttr("cloudscale_subnet.basic", "dns_servers.#", "0"),
+				),
+			},
 		},
 	})
 }
@@ -180,6 +223,28 @@ func TestAccCloudscaleSubnet_ServerWithPublicAndPrivate(t *testing.T) {
 	})
 }
 
+func TestAccCloudscaleSubnet_ValidationError(t *testing.T) {
+	rInt := acctest.RandInt()
+
+	resource.ParallelTest(t, resource.TestCase{
+		PreCheck:     func() { testAccPreCheck(t) },
+		Providers:    testAccProviders,
+		CheckDestroy: testAccCheckCloudscaleSubnetDestroy,
+		Steps: []resource.TestStep{
+			{
+				Config:      subnetconfigInvalidDnsCombination(rInt),
+				ExpectError: regexp.MustCompile(`Error: Conflicting configuration arguments.*`),
+				Check:       resource.ComposeTestCheckFunc(),
+			},
+			{
+				Config:      subnetconfigInvalidEmptyDnsCombination(rInt),
+				ExpectError: regexp.MustCompile(`Error: Conflicting configuration arguments.*`),
+				Check:       resource.ComposeTestCheckFunc(),
+			},
+		},
+	})
+}
+
 func TestAccCloudscaleSubnet_ServerAndMultipleSubnets(t *testing.T) {
 	count := 2
 	networks := make([]cloudscale.Network, count, count)
@@ -317,9 +382,10 @@ func TestAccCloudscaleSubnet_import_basic(t *testing.T) {
 				),
 			},
 			{
-				ResourceName:      "cloudscale_subnet.basic",
-				ImportState:       true,
-				ImportStateVerify: true,
+				ResourceName:            "cloudscale_subnet.basic",
+				ImportState:             true,
+				ImportStateVerify:       true,
+				ImportStateVerifyIgnore: []string{"disable_dns_servers"},
 			},
 			{
 				ResourceName:      "cloudscale_subnet.basic",
@@ -488,6 +554,41 @@ resource "cloudscale_subnet" "basic" {
 `)
 }
 
+func subnetconfigNoDns(rInt int) string {
+	return networkconfigMinimal(rInt, false) + "\n" + fmt.Sprintf(`
+resource "cloudscale_subnet" "basic" {
+  cidr            = "10.11.12.0/24"
+  network_uuid    = cloudscale_network.basic.id
+  gateway_address = "10.11.12.10"
+  disable_dns_servers = true
+}
+`)
+}
+
+func subnetconfigInvalidDnsCombination(rInt int) string {
+	return networkconfigMinimal(rInt, false) + "\n" + fmt.Sprintf(`
+resource "cloudscale_subnet" "basic" {
+  cidr            = "10.11.12.0/24"
+  network_uuid    = cloudscale_network.basic.id
+  gateway_address = "10.11.12.10"
+  dns_servers     = ["1.2.3.4", "5.6.7.8", "9.10.11.12"]
+  disable_dns_servers = true
+}
+`)
+}
+
+func subnetconfigInvalidEmptyDnsCombination(rInt int) string {
+	return networkconfigMinimal(rInt, false) + "\n" + fmt.Sprintf(`
+resource "cloudscale_subnet" "basic" {
+  cidr            = "10.11.12.0/24"
+  network_uuid    = cloudscale_network.basic.id
+  gateway_address = "10.11.12.10"
+  dns_servers     = []
+  disable_dns_servers = true
+}
+`)
+}
+
 func serverConfigWithPublicAndLayerThree(rInt int, fixedAddress string) string {
 	template := `
 resource "cloudscale_server" "basic" {

docs/resources/subnet.md

@@ -53,7 +53,8 @@ The following arguments are supported when creating/changing subnets:
 * `cidr` - (Required) The address range in CIDR notation. Must be at least /24.
 * `network_uuid` - (Required) The network of the subnet.
 * `gateway_address` - (Optional) The gateway address of the subnet.
-* `dns_servers` - (Optional) A list of DNS resolver IP addresses, that act as DNS servers.
+* `dns_servers` - (Optional) A list of DNS resolver IP addresses, that act as DNS servers. If not defined, default DNS servers are used. Do not explicitly set to an empty list (`dns_servers = []`), use `disable_dns_servers` instead.
+* `disable_dns_servers` - (Optional) If set to true, no DNS servers are set. Can not be used together with `dns_servers`.
 * `tags` - (Optional) Tags allow you to assign custom metadata to resources:
   ```
   tags = {

examples/.gitignore

@@ -0,0 +1,3 @@
+.terraform*
+terraform.tfstate
+terraform.tfstate.backup