Add new internal API cstack_sync

This allows one to force sync the state of xapi db with the cluster
stack, useful for cluster API methods change the state of the cluster.

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

ocaml/idl/datamodel_cluster.ml

@@ -169,6 +169,16 @@ let pool_resync =
     ~params:[(Ref _cluster, "self", "The cluster to resync")]
     ~lifecycle ~allowed_roles:_R_POOL_OP ~errs:[] ()
 
+let cstack_sync =
+  call ~name:"cstack_sync"
+    ~doc:
+      "Sync xapi db with the cluster stack synchronously, generate alerts as \
+       needed. Only happens on the coordinator as this is where the cluster \
+       watcher perform updates."
+    ~params:[(Ref _cluster, "self", "The cluster to sync")]
+    ~hide_from_docs:true ~pool_internal:true ~lifecycle
+    ~allowed_roles:_R_POOL_OP ~errs:[] ()
+
 let t =
   create_obj ~name:_cluster ~descr:"Cluster-wide Cluster metadata"
     ~doccomments:[] ~gen_constructor_destructor:false ~gen_events:true
@@ -245,5 +255,6 @@ let t =
       ; pool_force_destroy
       ; pool_destroy
       ; pool_resync
+      ; cstack_sync
       ]
     ()

ocaml/xapi/message_forwarding.ml

@@ -6399,6 +6399,14 @@ functor
                ) ;
                debug "Cluster.pool_resync for host %s" (Ref.string_of host)
            )
+
+      let cstack_sync ~__context ~self =
+        info "Cluster.cstack_sync cluster %s" (Ref.string_of self) ;
+        let local_fn = Local.Cluster.cstack_sync ~self in
+        let coor = Helpers.get_master ~__context in
+        do_op_on ~local_fn ~__context ~host:coor (fun session_id rpc ->
+            Client.Cluster.cstack_sync ~rpc ~session_id ~self
+        )
     end
 
     module Cluster_host = struct

ocaml/xapi/xapi_cluster.ml

@@ -294,3 +294,8 @@ let pool_resync ~__context ~self:_ =
       )
 (* If host.clustering_enabled then resync_host should successfully
    find or create a matching cluster_host which is also enabled *)
+
+let cstack_sync ~__context ~self =
+  debug "%s: sync db data with cluster stack" __FUNCTION__ ;
+  Watcher.on_corosync_update ~__context ~cluster:self
+    ["Updates due to cluster api calls"]

ocaml/xapi/xapi_cluster.mli

@@ -74,3 +74,13 @@ val pool_resync : __context:Context.t -> self:API.ref_Cluster -> unit
     Cluster_host objects (ie., one for each host in the pool if the Cluster
     has [pool_auto_join] set. If there is a failure, this function must return
     an error that enables the administrator to fix the problem. *)
+
+val cstack_sync : __context:Context.t -> self:API.ref_Cluster -> unit
+(** [cstack_sync ~__context ~self] is the implementation of the internal XenAPI method,
+which synchronously performs a diagnostics call to xapi-clusterd and updates the
+xapi db according to the call. This is used internally by cluster-host-create/destroy
+to generate the correct alert as a result of the API call. The other part of the
+alerts generated due to network failure (e.g. a host left as its network is down)
+is handled by the cluster watcher. This call only happens on the coordinator as that
+is where the cluster watcher performs the updates, which shares the code with
+this function.  *)