Make provider-level zone optional.

nat-henderson · nat-henderson · commit 79f473c8964f · 2017-12-04T23:16:10.000Z
Individual resources will fail if they can't find a zone.
diff --git a/google/provider.go b/google/provider.go
@@ -49,7 +49,7 @@ func Provider() terraform.ResourceProvider {
 
 			"zone": &schema.Schema{
 				Type:     schema.TypeString,
-				Required: true,
+				Optional: true,
 				DefaultFunc: schema.MultiEnvDefaultFunc([]string{
 					"GOOGLE_ZONE",
 					"GCLOUD_ZONE",
