zone field in compute disk should be optional (#1631)

google/resource_compute_disk.go

@@ -269,12 +269,6 @@ func resourceComputeDisk() *schema.Resource {
 				Required: true,
 				ForceNew: true,
 			},
-			"zone": {
-				Type:             schema.TypeString,
-				Required:         true,
-				ForceNew:         true,
-				DiffSuppressFunc: compareSelfLinkOrResourceName,
-			},
 			"description": {
 				Type:     schema.TypeString,
 				Optional: true,
@@ -302,6 +296,13 @@ func resourceComputeDisk() *schema.Resource {
 				ForceNew: true,
 				Default:  "pd-standard",
 			},
+			"zone": {
+				Type:             schema.TypeString,
+				Computed:         true,
+				Optional:         true,
+				ForceNew:         true,
+				DiffSuppressFunc: compareSelfLinkOrResourceName,
+			},
 			"disk_encryption_key": {
 				Type:             schema.TypeList,
 				Optional:         true,

website/docs/r/compute_disk.html.markdown

@@ -75,9 +75,6 @@ The following arguments are supported:
   first character must be a lowercase letter, and all following
   characters must be a dash, lowercase letter, or digit, except the last
   character, which cannot be a dash.
-* `zone` -
-  (Required)
-  A reference to the zone where the disk resides.
 
 
 - - -
@@ -114,6 +111,9 @@ The following arguments are supported:
   (Optional)
   URL of the disk type resource describing which disk type to use to
   create the disk. Provide this when creating the disk.
+* `zone` -
+  (Optional)
+  A reference to the zone where the disk resides.
 * `disk_encryption_key` -
   (Optional)
   Encrypts the disk using a customer-supplied encryption key.