config: allow config filename per repo

lib/action.ml

@@ -286,7 +286,7 @@ module Action (Github_api : Api.Github) (Slack_api : Api.Slack) = struct
     | Github.Push commit_pushed_notification ->
       let commits = commit_pushed_notification.commits in
       let modified_files = List.concat_map Github.modified_files_of_commit commits in
-      let config_was_modified = List.exists (String.equal ctx.config_filename) modified_files in
+      let config_was_modified = List.exists (String.equal (Context.get_config_filename ctx repo.url)) modified_files in
       if config_was_modified then fetch_config ~ctx ~repo else Lwt.return @@ Ok ()
     | _ -> Lwt.return @@ Ok ()
 

lib/api_local.ml

@@ -29,8 +29,8 @@ let get_repo_member_cache ~(repo : Github_t.repository) ~kind ~ref_ ~of_string =
   with_cache_file url of_string
 
 module Github : Api.Github = struct
-  let get_config ~(ctx : Context.t) ~repo:_ =
-    let url = Filename.concat cwd ctx.config_filename in
+  let get_config ~(ctx : Context.t) ~(repo : Github_t.repository) =
+    let url = Filename.concat cwd (Context.get_config_filename ctx repo.url) in
     with_cache_file url Config_j.config_of_string
 
   let get_api_commit ~ctx:_ ~repo ~sha =

lib/api_remote.ml

@@ -29,7 +29,7 @@ module Github : Api.Github = struct
 
   let get_config ~(ctx : Context.t) ~repo =
     let secrets = Context.get_secrets_exn ctx in
-    let url = contents_url ~repo ~path:ctx.config_filename in
+    let url = contents_url ~repo ~path:(Context.get_config_filename ctx repo.url) in
     let token = Context.gh_token_of_secrets secrets repo.url in
     let headers = build_headers ?token () in
     match%lwt http_request ~headers `GET url with

lib/config.atd

@@ -53,6 +53,8 @@ type repo_config = {
   ?gh_token : string nullable;
   (* GitHub webhook secret token to secure the webhook *)
   ?gh_hook_secret : string nullable;
+  (* override the default config filename for one repository *)
+  ?config_filename : string nullable;
 }
 
 (* This is the structure of the secrets file which stores sensitive information, and

lib/context.ml

@@ -34,6 +34,14 @@ let get_secrets_exn ctx =
   | None -> context_error "secrets is uninitialized"
   | Some secrets -> secrets
 
+let get_config_filename ctx repo_url =
+  match get_secrets_exn ctx with
+  | exception Context_error _ -> ctx.config_filename
+  | secrets ->
+  match List.find_opt (fun r -> String.equal r.Config_t.url repo_url) secrets.repos with
+  | None | Some { config_filename = None; _ } -> ctx.config_filename
+  | Some { config_filename = Some f; _ } -> f
+
 let find_repo_config ctx repo_url = Stringtbl.find_opt ctx.config repo_url
 
 let find_repo_config_exn ctx repo_url =

test/test.ml

@@ -35,7 +35,9 @@ let process_gh_payload ~(secrets : Config_t.secrets) ~config (kind, path, state_
   let make_test_context event =
     let repo = Github.repo_of_notification @@ Github.parse_exn headers event in
     (* overwrite repo url in secrets with that of notification for this test case *)
-    let secrets = { secrets with repos = [ { url = repo.url; gh_token = None; gh_hook_secret = None } ] } in
+    let secrets =
+      { secrets with repos = [ { url = repo.url; gh_token = None; gh_hook_secret = None; config_filename = None } ] }
+    in
     let ctx = Context.make () in
     ctx.secrets <- Some secrets;
     let (_ : State_t.repo_state) = State.find_or_add_repo ctx.state repo.url in