rabbitmq: make all dependencies explicit

Some things were provided by default, some by systemd unit and some
were just miraculously working. This turns them into explicit
dependencies of the package itself, making everything properly
overrideable.

+ providing glibcLocales fixes elixir compile warnings

+ providing systemd dependency allows rabbit to use systemctl for unit
  activation check instead of falling back to sleep. This was seen as
  a warning during startup.

nixos/modules/services/amqp/rabbitmq.nix

@@ -165,7 +165,10 @@ in {
       after = [ "network.target" "epmd.socket" ];
       wants = [ "network.target" "epmd.socket" ];
 
-      path = [ cfg.package pkgs.procps ];
+      path = [
+        cfg.package
+        pkgs.coreutils # mkdir/chown/chmod for preStart
+      ];
 
       environment = {
         RABBITMQ_MNESIA_BASE = "${cfg.dataDir}/mnesia";

pkgs/servers/amqp/rabbitmq-server/default.nix

@@ -1,5 +1,6 @@
 { stdenv, fetchurl, erlang, elixir, python, libxml2, libxslt, xmlto
 , docbook_xml_dtd_45, docbook_xsl, zip, unzip, rsync, getconf, socat
+, procps, coreutils, gnused, systemd, glibcLocales
 , AppKit, Carbon, Cocoa
 }:
 
@@ -15,23 +16,39 @@ stdenv.mkDerivation rec {
   };
 
   buildInputs =
-    [ erlang elixir python libxml2 libxslt xmlto docbook_xml_dtd_45 docbook_xsl zip unzip rsync ]
+    [ erlang elixir python libxml2 libxslt xmlto docbook_xml_dtd_45 docbook_xsl zip unzip rsync glibcLocales ]
     ++ stdenv.lib.optionals stdenv.isDarwin [ AppKit Carbon Cocoa ];
 
   outputs = [ "out" "man" "doc" ];
 
   installFlags = [ "PREFIX=$(out)" "RMQ_ERLAPP_DIR=$(out)" ];
   installTargets = [ "install" "install-man" ];
 
-  runtimePath = stdenv.lib.makeBinPath [getconf erlang socat];
+  preBuild = ''
+    export LANG=C.UTF-8 # fix elixir locale warning
+  '';
+
+  runtimePath = stdenv.lib.makeBinPath [
+    erlang
+    getconf # for getting memory limits
+    socat systemd procps # for systemd unit activation check
+    gnused coreutils # used by helper scripts
+  ];
   postInstall = ''
-    echo 'PATH=${runtimePath}:''${PATH:+:}$PATH' >> $out/sbin/rabbitmq-env
+    # rabbitmq-env calls to sed/coreutils, so provide everything early
+    sed -i $out/sbin/rabbitmq-env -e '2s|^|PATH=${runtimePath}\''${PATH:+:}\$PATH/\n|'
+
+    # rabbitmq-server script uses `dirname` to get hold of a
+    # rabbitmq-env, so let's provide this file directly. After that
+    # point everything is OK - the PATH above will kick in
+    substituteInPlace $out/sbin/rabbitmq-server \
+      --replace '`dirname $0`/rabbitmq-env' \
+                "$out/sbin/rabbitmq-env"
 
-    # we know exactly where rabbitmq is gonna be,
-    # so we patch that into the env-script
-    substituteInPlace $out/sbin/rabbitmq-env \
-      --replace 'RABBITMQ_SCRIPTS_DIR=`dirname $SCRIPT_PATH`' \
-                "RABBITMQ_SCRIPTS_DIR=$out/sbin"
+    # We know exactly where rabbitmq is gonna be, so we patch that into the env-script.
+    # By doing it early we make sure that auto-detection for this will
+    # never be executed (somewhere below in the script).
+    sed -i $out/sbin/rabbitmq-env -e "2s|^|RABBITMQ_SCRIPTS_DIR=$out/sbin\n|"
 
     # there’s a few stray files that belong into share
     mkdir -p $doc/share/doc/rabbitmq-server