CP-17481: expose the control domain id on the host so it is distinguishable from other control domains

Signed-off-by: Konstantina Chremmou <konstantina.chremmou@citrix.com>

Author: Konstantina Chremmou

ocaml/client_records/records.ml

@@ -1096,6 +1096,7 @@ let host_record rpc session_id host =
 			make_field ~name:"virtual-hardware-platform-versions" 
 				~get:(fun () -> String.concat "; " (List.map Int64.to_string (x ()).API.host_virtual_hardware_platform_versions)) 
 				~get_set:(fun () -> List.map Int64.to_string (x ()).API.host_virtual_hardware_platform_versions) ();
+			make_field ~name:"control-domain-uuid" ~get:(fun () -> get_uuid_from_ref (x ()).API.host_control_domain) ();
 		]}
 
 let vdi_record rpc session_id vdi =

ocaml/idl/datamodel.ml

@@ -4683,6 +4683,7 @@ let host =
 	field ~qualifier:RW ~in_product_since:rel_tampa ~default_value:(Some (VMap [])) ~ty:(Map (String, String)) "guest_VCPUs_params" "VCPUs params to apply to all resident guests";
 	field ~qualifier:RW ~in_product_since:rel_cream ~default_value:(Some (VEnum "enabled")) ~ty:host_display "display" "indicates whether the host is configured to output its console to a physical display device";
 	field ~qualifier:DynamicRO ~in_product_since:rel_cream ~default_value:(Some (VSet [VInt 0L])) ~ty:(Set (Int)) "virtual_hardware_platform_versions" "The set of versions of the virtual hardware platform that the host can offer to its guests";
+	field ~qualifier:DynamicRO ~default_value:(Some (VRef (Ref.string_of Ref.null))) ~in_product_since:rel_dundee_plus ~ty:(Ref _vm) "control_domain" "The control domain (domain 0)";
  ])
 	()
 

ocaml/xapi/create_misc.ml

@@ -133,11 +133,12 @@ let (+++) = Int64.add
 (** This function makes sure there is exactly one record of each type. *)
 (** It updates existing records if they are found, or else creates new *)
 (** records for any records that are missing.                          *)
-let rec ensure_domain_zero_records ~__context (host_info: host_info) : unit =
+let rec ensure_domain_zero_records ~__context ~host (host_info: host_info) : unit =
 	let domain_zero_ref = ensure_domain_zero_record ~__context host_info in
 	ensure_domain_zero_console_record ~__context ~domain_zero_ref;
 	ensure_domain_zero_guest_metrics_record ~__context ~domain_zero_ref host_info;
-	ensure_domain_zero_shadow_record ~__context ~domain_zero_ref
+	ensure_domain_zero_shadow_record ~__context ~domain_zero_ref;
+	Db.Host.set_control_domain ~__context ~self:host ~value:domain_zero_ref
 
 and ensure_domain_zero_record ~__context (host_info: host_info): [`VM] Ref.t =
 	let ref_lookup () = Helpers.get_domain_zero ~__context in

ocaml/xapi/create_misc.mli

@@ -32,7 +32,7 @@ type host_info = {
 val read_dom0_memory_usage : unit -> int64 option
 val read_localhost_info : unit -> host_info
 
-val ensure_domain_zero_records : __context:Context.t -> host_info -> unit
+val ensure_domain_zero_records : __context:Context.t -> host:[`host] Ref.t -> host_info -> unit
 
 val create_root_user : __context:Context.t -> unit
 

ocaml/xapi/dbsync_slave.ml

@@ -280,13 +280,13 @@ let update_env __context sync_keys =
     Create_misc.create_host_cpu ~__context;
   );
 
+  let localhost = Helpers.get_localhost ~__context in
+
   switched_sync Xapi_globs.sync_create_domain_zero (fun () ->
     debug "creating domain 0";
-    Create_misc.ensure_domain_zero_records ~__context info;
+    Create_misc.ensure_domain_zero_records ~__context ~host:localhost info;
   );
 
-  let localhost = Helpers.get_localhost ~__context in
-
   switched_sync Xapi_globs.sync_crashdump_resynchronise (fun () ->
     debug "resynchronising host crashdumps";
     Xapi_host_crashdump.resynchronise ~__context ~host:localhost;

ocaml/xapi/xapi_host.ml

@@ -617,6 +617,7 @@ let create ~__context ~uuid ~name_label ~name_description ~hostname ~address ~ex
 	~guest_VCPUs_params:[]
 	~display:`enabled
 	~virtual_hardware_platform_versions:(if host_is_us then Xapi_globs.host_virtual_hardware_platform_versions else [0L])
+	~control_domain:Ref.null
   ;
   (* If the host we're creating is us, make sure its set to live *)
   Db.Host_metrics.set_last_updated ~__context ~self:metrics ~value:(Date.of_float (Unix.gettimeofday ()));