CP-50537: Propagate originator as a http request header

XenAPI.py now passes an additional originator header when making
requests to xapi, if the "ORIGINATOR" env var is present.
Sm_exec now passes an env var, "ORIGINATOR=SM".

To classify the threads correctly, we first need to determine the
requests originators. This commit makes it possibly to explicitly
state the originators as headers.

Signed-off-by: Gabriel Buica <[email protected]>

Author: GabrielBuica

ocaml/libs/http-lib/http.ml

@@ -132,6 +132,8 @@ module Hdr = struct
 
   let location = "location"
 
+  let originator = "originator"
+
   let traceparent = "traceparent"
 
   let hsts = "strict-transport-security"
@@ -688,6 +690,14 @@ module Request = struct
     let frame_header = if x.frame then make_frame_header headers else "" in
     frame_header ^ headers ^ body
 
+  let with_originator_of req f =
+    Option.iter
+      (fun req ->
+        let originator = List.assoc_opt Hdr.originator req.additional_headers in
+        f originator
+      )
+      req
+
   let traceparent_of req =
     let open Tracing in
     let ( let* ) = Option.bind in

ocaml/libs/http-lib/http.mli

@@ -129,6 +129,8 @@ module Request : sig
   val to_wire_string : t -> string
   (** [to_wire_string t] returns a string which could be sent to a server *)
 
+  val with_originator_of : t option -> (string option -> unit) -> unit
+
   val traceparent_of : t -> Tracing.Span.t option
 
   val with_tracing :

ocaml/xapi/sm_exec.ml

@@ -38,6 +38,15 @@ let with_dbg ~name ~dbg f =
 (*********************************************************************************************)
 (* Random utility functions *)
 
+let env_vars =
+  Some
+    (Array.concat
+       [
+         Forkhelpers.default_path_env_pair
+       ; Env_record.to_string_array [Env_record.pair ("ORIGINATOR", "SM")]
+       ]
+    )
+
 type call = {
     (* All calls are performed by a specific Host with a special Session and device_config *)
     host_ref: API.ref_host
@@ -355,7 +364,7 @@ let exec_xmlrpc ~dbg ?context:_ ?(needs_session = true) (driver : string)
               let env, exe, args =
                 match Xapi_observer_components.is_smapi_enabled () with
                 | false ->
-                    (None, exe, args)
+                    (env_vars, exe, args)
                 | true ->
                     Xapi_observer_components.env_exe_args_of
                       ~component:Xapi_observer_components.SMApi ~exe ~args

ocaml/xapi/xapi_observer_components.ml

@@ -103,13 +103,15 @@ let dir_name_of_component component =
 
 let env_exe_args_of ~component ~exe ~args =
   let dir_name_value = Filename.quote (dir_name_of_component component) in
+  let originator = match component with SMApi -> "SM" | _ -> "none" in
   let env_vars =
     Array.concat
       [
         Forkhelpers.default_path_env_pair
       ; Env_record.to_string_array
           [
-            Env_record.pair ("OBSERVER_CONFIG_DIR", dir_name_value)
+            Env_record.pair ("ORIGINATOR", originator)
+          ; Env_record.pair ("OBSERVER_CONFIG_DIR", dir_name_value)
           ; Env_record.pair ("PYTHONPATH", Filename.dirname exe)
           ]
       ]

python3/examples/XenAPI/XenAPI.py

@@ -119,11 +119,18 @@ def with_tracecontext(self):
             for k, v in headers.items():
                 self.add_extra_header(k, v)
 
+    def with_originator(self):
+        originator_k = "ORIGINATOR"
+        originator_v = os.getenv(originator_k, None)
+        if originator_v:
+            self.add_extra_header(originator_k.lower(), originator_v)
+
     def make_connection(self, host):
         # clear the extra headers when making a new connection. This makes sure
         # headers such as "traceparent" do not get duplicated.
         self._extra_headers = []
         self.with_tracecontext()
+        self.with_originator()
 
         # compatibility with parent xmlrpclib.Transport HTTP/1.1 support
         if self._connection and host == self._connection[0]: