geoserver: fix startup script

Set GEOSERVER_DATA_DIR to current working
directory if not provided.

pkgs/servers/geospatial/geoserver/data-dir.patch

@@ -0,0 +1,18 @@
+--- a/bin/startup.sh
++++ b/bin/startup.sh
+@@ -66,12 +66,9 @@ fi
+ 
+ #Find the configuration directory: GEOSERVER_DATA_DIR
+ if [ -z "${GEOSERVER_DATA_DIR:-}" ]; then
+-    if [ -r "${GEOSERVER_HOME}/data_dir" ]; then
+-        export GEOSERVER_DATA_DIR="${GEOSERVER_HOME}/data_dir"
+-    else
+-        echo "No GEOSERVER_DATA_DIR found, using application defaults"
+-	      GEOSERVER_DATA_DIR=""
+-    fi
++  echo "GEOSERVER_DATA_DIR is not provided. Using $(pwd)/geoserver/data_dir directory"
++  mkdir -p "$(pwd)"/geoserver/data_dir
++  GEOSERVER_DATA_DIR="$(pwd)/geoserver/data_dir"
+ fi
+ 
+ cd "${GEOSERVER_HOME}" || exit 1

pkgs/servers/geospatial/geoserver/default.nix

@@ -9,6 +9,11 @@ stdenv.mkDerivation rec {
     sha256 = "sha256-xX1rAONMh5XSWGPXkVMemAvG34DDNmu2018HsTvY7G0=";
   };
 
+  patches = [
+    # set GEOSERVER_DATA_DIR to current working directory if not provided
+    ./data-dir.patch
+  ];
+
   sourceRoot = ".";
   nativeBuildInputs = [ unzip makeWrapper ];