Install latest stable program version when version not provided

Author: Santeri Hiltunen

bin/install.ml

@@ -18,7 +18,8 @@
 
 open Node_shim
 
-let usage = "Usage: node-shim-install <program> <version>"
+let usage = "Usage: node-shim-install <program> [version]\n\n" ^
+  "If version is not given will install latest stable version of program.\n"
 
 let () =
   let arg_spec = [] in
@@ -32,8 +33,8 @@ let () =
   in
   Arg.parse arg_spec parse_anon usage;
   match (!program, !version) with
-  | None, _
-  | _, None ->
+  | None, _ ->
     Arg.usage arg_spec usage;
     exit 1
+  | Some p, None -> Install.install_latest p
   | Some p, Some v -> Install.install p v

lib/install.ml

@@ -69,5 +69,19 @@ let install' program version =
   extracted_dir_name program version >>= fun extracted_dir ->
   Lwt_unix.rename (File.join [program_dir; extracted_dir]) version_dir
 
+let resolve_latest_version program =
+  let program_name = Program.to_string program in
+  let version_url = Printf.sprintf "https://semver.io/%s/stable" program_name in
+  Lwt_io.printlf "Resolving latest stable version of %s" program_name >>= fun () ->
+  Unix_utils.get_url version_url >>= fun version ->
+  Lwt.return (Version.of_string (String.trim version))
+
+let install_latest' program =
+  resolve_latest_version program >>= fun version ->
+  install' program version
+
 let install program version =
-  Lwt_main.run (install' program version);
+  Lwt_main.run (install' program version)
+
+let install_latest program =
+  Lwt_main.run (install_latest' program)

lib/install.mli

@@ -17,3 +17,5 @@
 *)
 
 val install : Program.t -> Version.t -> unit
+
+val install_latest : Program.t -> unit

lib/unix_utils.ml

@@ -38,5 +38,8 @@ let mkdirp path =
 let download url target =
   exec [|"wget"; "--quiet"; "-O"; target; url|]
 
+let get_url url =
+  Lwt_process.pread ("", [|"wget"; "-qO-"; url|])
+
 let extract archive target_dir =
   exec [|"tar"; "-xzf"; archive; "-C"; target_dir|]