make network dns enabled by default (#1100)

https://libvirt.org/formatnetwork.html#addressing specifies dns is disabled only if
enable="no", but if omitted, it is enabled by default.

However, it claims if disabled, it would ignore the dns entries, but in reality
it fails with "error: XML error: Extra data in disabled network".

This change makes:

- if enabled is omitted, we use the libvirt default
- we only add dns information to the xml if enabled

Author: dmacvicar

libvirt/network_dns.go

@@ -200,18 +200,6 @@ func getDNSForwardersFromResource(d *schema.ResourceData) ([]libvirtxml.NetworkD
 	return dnsForwarders, nil
 }
 
-// getDNSEnableFromResource returns string to enable ("yes") or disable ("no") dns
-// in the network definition.
-func getDNSEnableFromResource(d *schema.ResourceData) string {
-	if dnsEnabled, ok := d.GetOk(dnsPrefix + ".enabled"); ok {
-		if dnsEnabled.(bool) {
-			return "yes" // this "boolean" must be "yes"|"no"
-		}
-		return "no"
-	}
-	return "no"
-}
-
 // getDNSSRVFromResource returns a list of libvirt's DNS SRVs
 // in the network definition.
 func getDNSSRVFromResource(d *schema.ResourceData) ([]libvirtxml.NetworkDNSSRV, error) {

libvirt/resource_libvirt_network.go

@@ -12,6 +12,8 @@ import (
 	"github.com/hashicorp/terraform-plugin-sdk/v2/helper/resource"
 	"github.com/hashicorp/terraform-plugin-sdk/v2/helper/schema"
 	"libvirt.org/go/libvirtxml"
+
+	"github.com/dmacvicar/terraform-provider-libvirt/libvirt/util"
 )
 
 const (
@@ -102,6 +104,7 @@ func resourceLibvirtNetwork() *schema.Resource {
 							Type:     schema.TypeBool,
 							Optional: true,
 							Required: false,
+							Default: true,
 						},
 						"local_only": {
 							Type:     schema.TypeBool,
@@ -378,30 +381,31 @@ func resourceLibvirtNetworkCreate(ctx context.Context, d *schema.ResourceData, m
 		}
 		networkDef.IPs = ips
 
-		dnsEnabled := getDNSEnableFromResource(d)
+		if dnsEnabled, ok := d.GetOk(dnsPrefix + ".enabled"); ok && dnsEnabled.(bool) {
+			dnsForwarders, err := getDNSForwardersFromResource(d)
+			if err != nil {
+				return diag.FromErr(err)
+			}
 
-		dnsForwarders, err := getDNSForwardersFromResource(d)
-		if err != nil {
-			return diag.FromErr(err)
-		}
+			dnsSRVs, err := getDNSSRVFromResource(d)
+			if err != nil {
+				return diag.FromErr(err)
+			}
 
-		dnsSRVs, err := getDNSSRVFromResource(d)
-		if err != nil {
-			return diag.FromErr(err)
-		}
+			dnsHosts, err := getDNSHostsFromResource(d)
+			if err != nil {
+				return diag.FromErr(err)
+			}
 
-		dnsHosts, err := getDNSHostsFromResource(d)
-		if err != nil {
-			return diag.FromErr(err)
-		}
+			dns := libvirtxml.NetworkDNS{
+				Enable:     util.FormatBoolYesNo(dnsEnabled.(bool)),
+				Forwarders: dnsForwarders,
+				Host:       dnsHosts,
+				SRVs:       dnsSRVs,
+			}
 
-		dns := libvirtxml.NetworkDNS{
-			Enable:     dnsEnabled,
-			Forwarders: dnsForwarders,
-			Host:       dnsHosts,
-			SRVs:       dnsSRVs,
+			networkDef.DNS = &dns
 		}
-		networkDef.DNS = &dns
 	} else if networkDef.Forward.Mode == netModeBridge {
 		if networkDef.Bridge.Name == "" {
 			return diag.Errorf("'bridge' must be provided when using the bridged network mode")

website/docs/r/network.markdown

@@ -40,9 +40,9 @@ resource "libvirt_network" "kube_network" {
 
   # (Optional) DNS configuration
   dns {
-    # (Optional, default false)
-    # Set to true, if no other option is specified and you still want to 
-    # enable dns.
+    # (Optional, default true)
+    # If disabled, no dns will be setup for this network and dns configuration
+	# will be ignored.
     enabled = true
     # (Optional, default false)
     # true: DNS requests under this domain will only be resolved by the