Save CLI arguments to the lock file

This can be useful for reproducing the exact command
that generated a lock file

Signed-off-by: Nathan Rebours <nathan.p.rebours@gmail.com>

CHANGES.md

@@ -7,6 +7,8 @@
   @NathanReb)
 - Add command line options to complement or overwrite `x-opam-monorepo-*`
   fields. (#307, @NathanReb)
+- Save the `lock` CLI arguments in `x-opam-monorepo-cli-args` when generating a
+  lock file. (#309, @NathanReb)
 
 ### Changed
 

cli/lock.ml

@@ -449,6 +449,11 @@ let extract_source_config ~adjustment ~opam_monorepo_cwd ~opam_files
   Source_opam_config.make ~opam_monorepo_cwd ~adjustment
     ~local_opam_files_config
 
+let raw_cli_args () =
+  match Array.to_list Sys.argv with
+  | _bin :: "lock" :: args -> args
+  | _ -> assert false
+
 let run (`Root root) (`Recurse_opam recurse) (`Build_only build_only)
     (`Allow_jbuilder allow_jbuilder) (`Ocaml_version ocaml_version)
     (`Require_cross_compile require_cross_compile)
@@ -485,8 +490,9 @@ let run (`Root root) (`Recurse_opam recurse) (`Build_only build_only)
     Lockfile.create ~source_config ~root_packages:target_packages
       ~dependency_entries ~root_depexts:target_depexts ~duniverse ()
   in
+  let cli_args = raw_cli_args () in
   let* () =
-    Lockfile.save ~opam_monorepo_cwd:root ~file:lockfile_path lockfile
+    Lockfile.save ~opam_monorepo_cwd:root ~cli_args ~file:lockfile_path lockfile
   in
   Common.Logs.app (fun l ->
       l

lib/lockfile.ml

@@ -261,6 +261,21 @@ module Depexts = struct
     List.concat all |> List.sort_uniq ~cmp:compare_elm
 end
 
+module Cli_args = struct
+  (** Field used to store the raw command line arguments passed to [lock].
+      It is set but not read and therefore is not part of the main lock file
+      type. *)
+
+  type _t = string list
+
+  let name = "cli-args"
+  let shape = Serial_shape.(list string)
+  let from_opam_value value = Serial_shape.from_opam_val shape value
+  let to_opam_value t = Serial_shape.to_opam_val shape t
+  let field = Extra_field.make ~name ~to_opam_value ~from_opam_value
+  let add t opam = match t with [] -> opam | _ -> Extra_field.set field t opam
+end
+
 type t = {
   version : Version.t;
   root_packages : Root_packages.t;
@@ -364,12 +379,15 @@ let from_opam ~opam_monorepo_cwd ?file opam =
       source_config;
     }
 
-let save ~opam_monorepo_cwd ~file t =
-  let opam = to_opam ~opam_monorepo_cwd t in
+let save ~opam_monorepo_cwd ~cli_args ~file t =
+  let opam =
+    Cli_args.add cli_args
+      (to_opam ~opam_monorepo_cwd t)
+  in
   Bos.OS.File.with_oc file
     (fun oc () ->
-      OpamFile.OPAM.write_to_channel oc opam;
-      Ok ())
+       OpamFile.OPAM.write_to_channel oc opam;
+       Ok ())
     ()
   |> Result.join
 

lib/lockfile.mli

@@ -20,6 +20,7 @@ val ocaml_version : t -> OpamPackage.Version.t option
 
 val save :
   opam_monorepo_cwd:Fpath.t ->
+  cli_args:string list ->
   file:Fpath.t ->
   t ->
   (unit, [ `Msg of string ]) result

test/bin/cli-args-in-lockfile.t/cli-args-in-lockfile.opam

@@ -0,0 +1,5 @@
+opam-version: "2.0"
+depends: [
+  "dune"
+  "ocaml"
+]

test/bin/cli-args-in-lockfile.t/run.t

@@ -0,0 +1,7 @@
+When generating a lockfile, the CLI arguments passed to lock
+should be save to the lockfile
+
+  $ gen-minimal-repo
+  $ opam-monorepo lock --recurse --opam-provided [b] --opam-repositories '[file://$OPAM_MONOREPO_CWD/minimal-repo]' --ocaml-version 4.13.1 > /dev/null
+  $ opam show --just-file -fx-opam-monorepo-cli-args ./cli-args-in-lockfile.opam.locked
+  --recurse, --opam-provided, [b], --opam-repositories, [file://$OPAM_MONOREPO_CWD/minimal-repo], --ocaml-version, 4.13.1