diff --git a/docker/Dockerfile b/docker/Dockerfile
index 70457f0..e6b4d8a 100644
--- a/docker/Dockerfile
+++ b/docker/Dockerfile
@@ -3,6 +3,9 @@ FROM ubuntu:latest
 MAINTAINER Sah Lee <contact@leesah.name>
 
 ENV BASEDIR /tmp
+ENV CONFIGDIR /etc/shadowsocks
+ENV CONFIGFILE $CONFIGDIR/shadowsocks.json
+ENV PORT 8388
 
 # Install dependencies
 RUN apt-get update
@@ -25,13 +28,11 @@ RUN apt-get --purge autoremove -y git-core python-setuptools
 RUN rm -rf $BASEDIR/shadowsocks
 
 # Config file can be in a separated container
-ENV CONFIG_DIR /etc/shadowsocks
-ENV CONFIG_FILE $CONFIG_DIR/shadowsocks.json
-VOLUME ["$CONFIG_DIR"]
+VOLUME ["$CONFIGDIR"]
+ADD shadowsocks.json $CONFIGDIR
 
 # Port in the config file won't take affect. Instead we'll use 8388.
-ENV PORT 8388
 EXPOSE $PORT
 
 # Override the host and port in the config file.
-CMD ssserver --fast-open -c $CONFIG_FILE -s 0.0.0.0 -p $PORT
+CMD ssserver --fast-open -c $CONFIGFILE -s 0.0.0.0 -p $PORT