Merge pull request #32 from timvisher/feature/add-difficulty-knob

Add difficulty knob.

minecraft-server/Dockerfile

@@ -31,4 +31,4 @@ ENV MC_IMAGE=YES
 ENV UID=1000
 ENV MOTD A Minecraft Server Powered by Docker
 ENV JVM_OPTS -Xmx1024M -Xms1024M
-ENV TYPE=VANILLA VERSION=LATEST LEVEL=world PVP=true
+ENV TYPE=VANILLA VERSION=LATEST LEVEL=world PVP=true DIFFICULTY=easy

minecraft-server/README.md

@@ -128,6 +128,16 @@ up:
 
 ## Server configuration
 
+### Difficulty
+
+The difficulty level (default: `easy`) can be set like:
+
+    docker run -d -e DIFFICULTY=hard
+
+Valid values are: `peaceful`, `easy`, `normal`, and `hard`, and an
+error message will be output in the logs if it's not one of these
+values.
+
 ### Op/Administrator Players
 
 To add more "op" (aka adminstrator) users to your Minecraft server, pass the Minecraft usernames separated by commas via the `OPS` environment variable, such as

minecraft-server/start-minecraft.sh

@@ -97,6 +97,28 @@ if [ ! -e server.properties ]; then
     sed -i "/pvp\s*=/ c pvp=$PVP" /data/server.properties
   fi
 
+  if [ -n "$DIFFICULTY" ]; then
+    case $DIFFICULTY in
+      peaceful)
+        DIFFICULTY=0
+        ;;
+      easy)
+        DIFFICULTY=1
+        ;;
+      normal)
+        DIFFICULTY=2
+        ;;
+      hard)
+        DIFFICULTY=3
+        ;;
+      *)
+        echo "DIFFICULTY must be peaceful, easy, normal, or hard."
+        exit 1
+        ;;
+    esac
+    sed -i "/difficulty\s*=/ c difficulty=$DIFFICULTY" /data/server.properties
+  fi
+
   if [ -n "$MODE" ]; then
     case ${MODE,,?} in
       0|1|2|3)