CA-404512: Add feature flag to the new clustering interface

The new clustering interface uses a constructor `Extended` address when
a cluster hots is trying to join a cluster. This causes problems during
upgrades as a newly upgraded host might send out the new address format
to old hosts, which do not understand this format, causing the new hosts
not able to join.

The fix would be to use a new cluster_address feature flag/pool
restrictions to control the use of the new clustering interface. This makes
sure that the new interface would only be used if all of the hosts
understand this new interface, i.e. have this feature enabled. The
cluster_address feature is controlled by v6d and is pool-wide, therefore
the new interface would only be enabled if all v6ds are updated to the
correct level, which also implies that the accompanying xapi are updated
to the correct level.

Signed-off-by: Vincent Liu <[email protected]>

ocaml/xapi-types/features.ml

@@ -58,6 +58,7 @@ type feature =
   | USB_passthrough
   | Network_sriov
   | Corosync
+  | Cluster_address
   | Zstd_export
   | Pool_secret_rotation
   | Certificate_verification
@@ -123,6 +124,7 @@ let keys_of_features =
   ; (USB_passthrough, ("restrict_usb_passthrough", Negative, "USB_passthrough"))
   ; (Network_sriov, ("restrict_network_sriov", Negative, "Network_sriov"))
   ; (Corosync, ("restrict_corosync", Negative, "Corosync"))
+  ; (Cluster_address, ("restrict_cluster_address", Negative, "Cluster_address"))
   ; (Zstd_export, ("restrict_zstd_export", Negative, "Zstd_export"))
   ; ( Pool_secret_rotation
     , ("restrict_pool_secret_rotation", Negative, "Pool_secret_rotation")

ocaml/xapi-types/features.mli

@@ -65,6 +65,7 @@ type feature =
   | USB_passthrough  (** Enable the use of USB passthrough. *)
   | Network_sriov  (** Enable the use of Network SRIOV. *)
   | Corosync  (** Enable the use of corosync. *)
+  | Cluster_address  (** Enable the use of extended cluster address interface *)
   | Zstd_export  (** Enable the use of VM export with zstd compression. *)
   | Pool_secret_rotation  (** Enable Pool Secret Rotation *)
   | Certificate_verification  (** Used by XenCenter *)

ocaml/xapi/xapi_cluster.ml

@@ -65,12 +65,15 @@ let create ~__context ~pIF ~cluster_stack ~pool_auto_join ~token_timeout
       let hostuuid = Inventory.lookup Inventory._installation_uuid in
       let hostname = Db.Host.get_hostname ~__context ~self:host in
       let member =
-        Extended
-          {
-            ip= Ipaddr.of_string_exn (ipstr_of_address ip_addr)
-          ; hostuuid
-          ; hostname
-          }
+        if Xapi_cluster_helpers.cluster_address_enabled ~__context then
+          Extended
+            {
+              ip= Ipaddr.of_string_exn (ipstr_of_address ip_addr)
+            ; hostuuid
+            ; hostname
+            }
+        else
+          IPv4 (ipstr_of_address ip_addr)
       in
       let token_timeout_ms = Int64.of_float (token_timeout *. 1000.0) in
       let token_timeout_coefficient_ms =

ocaml/xapi/xapi_cluster_helpers.ml

@@ -12,6 +12,8 @@
  * GNU Lesser General Public License for more details.
  *)
 
+module D = Debug.Make (struct let name = __MODULE__ end)
+
 let finally = Xapi_stdext_pervasives.Pervasiveext.finally
 
 let all_cluster_operations = [`add; `remove; `enable; `disable; `destroy]
@@ -104,6 +106,12 @@ let with_cluster_operation ~__context ~(self : [`Cluster] API.Ref.t) ~doc ~op
       with _ -> ()
   )
 
+let cluster_address_enabled ~__context =
+  let r = Pool_features.is_enabled ~__context Features.Cluster_address in
+  D.debug "%s extended cluster address is %s" __FUNCTION__
+    (if r then "enabled" else "disabled") ;
+  r
+
 let corosync3_enabled ~__context =
   let pool = Helpers.get_pool ~__context in
   let restrictions = Db.Pool.get_restrictions ~__context ~self:pool in

ocaml/xapi/xapi_cluster_host.ml

@@ -126,12 +126,15 @@ let join_internal ~__context ~self =
       let host = Db.Cluster_host.get_host ~__context ~self in
       let hostname = Db.Host.get_hostname ~__context ~self:host in
       let member =
-        Extended
-          {
-            ip= Ipaddr.of_string_exn (ipstr_of_address ip_addr)
-          ; hostuuid
-          ; hostname
-          }
+        if Xapi_cluster_helpers.cluster_address_enabled ~__context then
+          Extended
+            {
+              ip= Ipaddr.of_string_exn (ipstr_of_address ip_addr)
+            ; hostuuid
+            ; hostname
+            }
+        else
+          IPv4 (ipstr_of_address ip_addr)
       in
       let ip_list =
         List.filter_map
@@ -338,14 +341,17 @@ let enable ~__context ~self =
       let hostuuid = Inventory.lookup Inventory._installation_uuid in
       let hostname = Db.Host.get_hostname ~__context ~self:host in
       let member =
-        Cluster_interface.(
-          Extended
-            {
-              ip= Ipaddr.of_string_exn (ipstr_of_address ip_addr)
-            ; hostuuid
-            ; hostname
-            }
-        )
+        if Xapi_cluster_helpers.cluster_address_enabled ~__context then
+          Cluster_interface.(
+            Extended
+              {
+                ip= Ipaddr.of_string_exn (ipstr_of_address ip_addr)
+              ; hostuuid
+              ; hostname
+              }
+          )
+        else
+          Cluster_interface.(IPv4 (ipstr_of_address ip_addr))
       in
       let cluster_ref = Db.Cluster_host.get_cluster ~__context ~self in
       let cluster_stack =