Add more info to the config event

bin/common.ml

@@ -1404,7 +1404,11 @@ let init_with_root ~(root : Workspace_root.t) (builder : Builder.t) =
     ];
   Dune_console.separate_messages c.builder.separate_error_messages;
   Option.iter c.stats ~f:(fun stats ->
-    let event = Dune_trace.Event.config () in
+    let event =
+      Dune_trace.Event.config
+        ~version:
+          (Build_info.V1.version () |> Option.map ~f:Build_info.V1.Version.to_string)
+    in
     Dune_trace.emit stats event);
   (* Setup hook for printing GC stats to a file *)
   at_exit (fun () ->

doc/changes/added/12908.md

@@ -0,0 +1,2 @@
+- Add `argv`, the process environment, and the dune version to the config event
+  in the trace (#12909, @rgrinberg)

src/dune_trace/dune_trace.ml

@@ -1,6 +1,5 @@
 open Stdune
 module Timestamp = Chrome_trace.Event.Timestamp
-module Json = Json
 
 module Mac = struct
   external open_fds : pid:int -> int = "dune_trace_open_fds"
@@ -135,9 +134,19 @@ module Event = struct
     Event.counter common args
   ;;
 
-  let config () =
+  let config ~version =
+    let args =
+      let args =
+        [ "build_dir", `String (Path.Build.to_string Path.Build.root)
+        ; "argv", `List (Array.to_list Sys.argv |> List.map ~f:Json.string)
+        ; "env", `List (Unix.environment () |> Array.to_list |> List.map ~f:Json.string)
+        ]
+      in
+      match version with
+      | None -> args
+      | Some v -> ("version", Stdune.Json.string v) :: args
+    in
     let open Chrome_trace in
-    let args = [ "build_dir", `String (Path.Build.to_string Path.Build.root) ] in
     let ts = Event.Timestamp.of_float_seconds (Unix.gettimeofday ()) in
     let common = Event.common_fields ~cat:[ "config" ] ~name:"config" ~ts () in
     Event.instant ~args common

src/dune_trace/dune_trace.mli

@@ -68,7 +68,7 @@ module Event : sig
 
   val scan_source : name:string -> start:float -> stop:float -> dir:Path.Source.t -> t
   val scheduler_idle : unit -> t
-  val config : unit -> t
+  val config : version:string option -> t
 
   module Rpc : sig
     type stage =