rabbitmq-server: Put files in $HOME by default

Before, files were put in /var, requiring the server to be run as a
privileged user even when just testing locally. This can be overridden
by setting the SYS_PREFIX env variable, or on a more coarse-grained
basis in /etc/rabbitmq/rabbitmq-env.conf

Signed-off-by: Shea Levy <shea@shealevy.com>

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

@@ -2,10 +2,12 @@
 , docbook_xml_dtd_45, docbook_xsl, zip, unzip }:
 
 stdenv.mkDerivation rec {
-  name = "rabbitmq-server-3.0.3";
+  name = "rabbitmq-server-${version}";
+
+  version = "3.0.3";
 
   src = fetchurl {
-    url = "http://www.rabbitmq.com/releases/rabbitmq-server/v3.0.3/${name}.tar.gz";
+    url = "http://www.rabbitmq.com/releases/rabbitmq-server/v${version}/${name}.tar.gz";
     sha256 = "07mp57xvszdrlgw8rgn9r9dpa6vdqdjk7f1dyh6a9sdg8s9fby38";
   };
 
@@ -20,6 +22,14 @@ stdenv.mkDerivation rec {
 
   installFlags = "TARGET_DIR=$(out)/libexec/rabbitmq SBIN_DIR=$(out)/sbin MAN_DIR=$(out)/share/man";
 
+  preInstall =
+    ''
+      sed -i \
+        -e 's|SYS_PREFIX=|SYS_PREFIX=''${SYS_PREFIX-''${HOME}/.rabbitmq/${version}}|' \
+        -e 's|CONF_ENV_FILE=''${SYS_PREFIX}\(.*\)|CONF_ENV_FILE=\1|' \
+        scripts/rabbitmq-defaults
+    '';
+
   postInstall =
     ''
       echo 'PATH=${erlang}/bin:${PATH:+:}$PATH' >> $out/sbin/rabbitmq-env