CP-44107: Add Interface.get_interface_positions

If networkd config.interface_order is None, then sort based
on the renamed interfaces name "ethx" to indicate its position,
else get positions from config.interface_order.

Signed-off-by: Changlei Li <changlei.li@cloud.com>

Author: changlei-li

ocaml/networkd/bin/network_server.ml

@@ -97,6 +97,22 @@ let read_config () =
       error "Could not interpret the configuration in management.conf"
   )
 
+let get_index_from_ethx name =
+  if String.starts_with ~prefix:"eth" name then
+    let index = String.sub name 3 (String.length name - 3) in
+    int_of_string_opt index
+  else
+    None
+
+let sort_based_on_ethx () =
+  Sysfs.list ()
+  |> List.filter_map (fun name ->
+         if Sysfs.is_physical name then
+           get_index_from_ethx name |> Option.map (fun i -> (name, i))
+         else
+           None
+     )
+
 let on_shutdown signal =
   let dbg = "shutdown" in
   Debug.with_thread_associated dbg
@@ -321,6 +337,24 @@ module Interface = struct
   let get_all dbg () =
     Debug.with_thread_associated dbg (fun () -> Sysfs.list ()) ()
 
+  let get_interface_positions dbg () =
+    Debug.with_thread_associated dbg
+      (fun () ->
+        match !config.interface_order with
+        | Some order ->
+            List.filter_map
+              (fun dev ->
+                if dev.present then
+                  Some (dev.name, dev.position)
+                else
+                  None
+              )
+              order
+        | None ->
+            sort_based_on_ethx ()
+      )
+      ()
+
   let exists dbg name =
     Debug.with_thread_associated dbg
       (fun () -> List.mem name (Sysfs.list ()))

ocaml/networkd/bin/networkd.ml

@@ -183,6 +183,7 @@ let bind () =
   S.set_gateway_interface set_gateway_interface ;
   S.set_dns_interface set_dns_interface ;
   S.Interface.get_all Interface.get_all ;
+  S.Interface.get_interface_positions Interface.get_interface_positions ;
   S.Interface.exists Interface.exists ;
   S.Interface.get_mac Interface.get_mac ;
   S.Interface.get_pci_bus_path Interface.get_pci_bus_path ;

ocaml/xapi-idl/network/network_interface.ml

@@ -420,6 +420,18 @@ module Interface_API (R : RPC) = struct
         ["Get list of all interface names"]
         (debug_info_p @-> unit_p @-> returning iface_list_p err)
 
+    let get_interface_positions =
+      let module T = struct
+        type _iface_position_list_t = (iface * int) list [@@deriving rpcty]
+      end in
+      let iface_position_list_p =
+        Param.mk ~description:["interface postion list"]
+          T._iface_position_list_t
+      in
+      declare "Interface.get_interface_positions"
+        ["Get list of interface names and their positions"]
+        (debug_info_p @-> unit_p @-> returning iface_position_list_p err)
+
     let exists =
       let result = Param.mk ~description:["existence"] Types.bool in
       declare "Interface.exists"