use only one flag and default to 0.0.0.0:9090

Author: rbjorklin

app/prometheus_unix.ml

@@ -42,54 +42,48 @@ module Unix_runtime = struct
   ]
 end
 
-type config = {
-  port : int option;
-  addr : string option;
-}
+type config = string option
 
 module Server = Prometheus_app.Cohttp(Cohttp_lwt_unix.Server)
 
-let serve config = match config.port, config.addr with
-  | None, _ -> []
-  | Some port, None ->
-    let mode = `TCP (`Port port) in
-    let callback = Server.callback in
-    let thread = Cohttp_lwt_unix.Server.create ~mode (Cohttp_lwt_unix.Server.make ~callback ()) in
-    [thread]
-  | Some port, Some addr  ->
+let bind addr port =
     let open! Unix in
     let [@ocaml.warning "-partial-match"] addrinfo :: _ =
-      getaddrinfo addr (Int.to_string port) [AI_SOCKTYPE SOCK_STREAM] in
+      getaddrinfo addr port [AI_SOCKTYPE SOCK_STREAM] in
     let socket = socket ~cloexec:true addrinfo.ai_family addrinfo.ai_socktype addrinfo.ai_protocol in
     let () = setsockopt socket SO_REUSEADDR true in
     let callback = Server.callback in
-    let () = listen socket 20 in
     let () = bind socket addrinfo.ai_addr in
+    let () = listen socket 20 in
     let mode = `TCP (`Socket (Lwt_unix.of_unix_file_descr socket)) in
     let thread = Cohttp_lwt_unix.Server.create ~mode (Cohttp_lwt_unix.Server.make ~callback ()) in
     [thread]
 
-let listen_prometheus_addr =
-  let open! Cmdliner in
-  let doc =
-    Arg.info ~docs:"MONITORING OPTIONS" ~docv:"ADDR" ~doc:
-      "Ip address on which to provide Prometheus metrics over HTTP."
-      ["listen-prometheus-addr"]
-  in
-  Arg.(value @@ opt (some string) None doc)
+let serve config =
+  let addr = "0.0.0.0" in
+  let port = "9090" in
+  match config with
+  | None -> []
+  | Some config_s ->
+    try
+      match (String.split_on_char ':' config_s) with
+      | [] -> bind addr port
+      | port :: [] -> bind addr port
+      | addr :: port :: [] -> bind addr port
+    with
+      | Match_failure _ -> Printf.printf "ERROR: Incorrect addr:port pair specified, prometheus listener not starting.\n"; flush_all (); []
+      [@@ocaml.warning "-partial-match"]
 
 let listen_prometheus =
   let open! Cmdliner in
   let doc =
-    Arg.info ~docs:"MONITORING OPTIONS" ~docv:"PORT" ~doc:
-      "Port on which to provide Prometheus metrics over HTTP."
+    Arg.info ~docs:"MONITORING OPTIONS" ~docv:"ADDR_PORT" ~doc:
+      "Address and port on which to provide Prometheus metrics over HTTP."
       ["listen-prometheus"]
   in
-  Arg.(value @@ opt (some int) None doc)
+  Arg.(value @@ opt (some string) None doc)
 
-let opts =
-  let combine port addr = { port; addr } in
-    Cmdliner.Term.(const combine $ listen_prometheus $ listen_prometheus_addr)
+let opts = listen_prometheus
 
 let () =
   let add (info, collector) =