CP-23026 pool join: add checks for software version, product_brand

This adds a generic check that can be asked to compare multiple
aspects of a product version before a host joins a pool. Currently,
_product_version and _product_brand are being checked between local host
and master.

Signed-off-by: Christian Lindig <[email protected]>

Author: lindig

ocaml/xapi/xapi_pool.ml

@@ -143,6 +143,40 @@ let pre_join_checks ~__context ~rpc ~session_id ~force =
     end
   in
 
+  (** [assert_version_matches] takes a list of [keys] into
+   * [API.host_software_version] and compares each version on
+   * localhost and pool master. A version difference or an
+   * undefined key leads to an assertion and blocks a host to join.
+   *)
+  let assert_version_matches keys =
+    let local =
+      Helpers.get_localhost ~__context
+      |> fun self -> Db.Host.get_record ~__context ~self
+      |> fun r -> r.API.host_software_version in
+    let master =
+      get_master rpc session_id
+      |> fun self -> Client.Host.get_record ~rpc ~session_id ~self
+      |> fun r -> r.API.host_software_version  in
+    let api_error fmt =
+      Printf.kprintf (fun msg ->
+        raise Api_errors.(Server_error(pool_hosts_not_homogeneous,[msg]))) fmt in
+    let compare key =
+      try
+        let local_v  = List.assoc key local  in
+        let master_v = List.assoc key master in
+        if local_v <> master_v then begin
+          error "pool join: software versions differ localhost[%s]=%s <> master[%s]=%s"
+            key local_v key master_v;
+          api_error "localhost[%s]=%s master[%s]=%s" (* avoid i18n *)
+            key local_v key master_v;
+        end
+      with Not_found ->
+        error "pool join: software version for key %s is undefined" key;
+        api_error "%s" key (* avoid i18n *)
+    in
+      List.iter compare keys
+  in
+
   let assert_homogeneous_updates () =
     let module S      = Helpers.StringSet in
     let local_host    = Helpers.get_localhost ~__context in
@@ -386,6 +420,7 @@ let pre_join_checks ~__context ~rpc ~session_id ~force =
   (* CA-247399: check first the API version and then the database schema *)
   assert_api_version_matches ();
   assert_db_schema_matches ();
+  assert_version_matches Xapi_globs.([_product_version; _product_brand]);
   assert_homogeneous_updates ();
   assert_homogeneous_primary_address_type ()