Build jar inside dockerized staged build

Dockerfile

@@ -1,3 +1,13 @@
+# Base image with maven installed already
+FROM maven:3.6.3-jdk-8 as builder
+
+# Copy whole project inside docker
+COPY . .
+
+# Build project
+RUN mvn clean package
+
+
 # Base image containing OpenJDK 8, maintained by RedHat
 FROM adoptopenjdk:8-jre-hotspot
 
@@ -23,8 +33,9 @@ USER $USER
 # Symlink to java executable to make it available to sudo user
 RUN sudo ln -s $JAVA_HOME/bin/java /usr/bin/java
 
-# Copy jar from target to working directory
-COPY target/*.jar /ward.jar
+# Copy jar and pom from builder image to working directory
+COPY --from=builder target/*.jar /ward.jar
+COPY --from=builder pom.xml /pom.xml
 
 EXPOSE 4000
 

README.md

@@ -129,7 +129,7 @@ Ward works nice on all popular operating systems, because it uses [OSHI](https:/
     Build for Docker
 
     1. Clone the project
-    2. mvn clean package
-    3. docker build --tag ward .
-    4. docker run --rm -it --name ward -p 4000:4000 -p <application port>:<application port> --privileged ward
-    5. Go to localhost:4000 in web browser, input the same application port
+    2. docker build --tag ward .
+    3. docker run --rm -it --name ward -p 4000:4000 -p <application port>:<application port> --privileged ward
+    4. Go to localhost:4000 in web browser, input the same application port
+    5. If you get error after being redirected to application port try hitting refresh.