CF-4258: review comment changes

Author: ksrihari09

docker/Dockerfile

@@ -1,3 +1,26 @@
+# Multi-stage build: first stage for building the application
+FROM openjdk:8-jdk-alpine AS builder
+
+# Install Maven
+RUN apk add --no-cache curl tar bash \
+    && mkdir -p /usr/share/maven /usr/share/maven/ref \
+    && curl -fsSL -o /tmp/apache-maven.tar.gz https://archive.apache.org/dist/maven/maven-3/3.8.8/binaries/apache-maven-3.8.8-bin.tar.gz \
+    && tar -xzf /tmp/apache-maven.tar.gz -C /usr/share/maven --strip-components=1 \
+    && rm -f /tmp/apache-maven.tar.gz \
+    && ln -s /usr/share/maven/bin/mvn /usr/bin/mvn
+
+# Set Maven environment
+ENV MAVEN_HOME /usr/share/maven
+ENV MAVEN_CONFIG "$USER_HOME_DIR/.m2"
+
+# Copy source code
+WORKDIR /app
+COPY . .
+
+# Build the application
+RUN mvn clean package -DskipTests
+
+# Second stage: runtime image
 FROM openjdk:8-jre-alpine
 
 LABEL maintainer="AtomHopperTeam@rackspace.com" \
@@ -41,9 +64,8 @@ RUN apk --no-cache add curl wget \
     && rm /tmp/tomcat.tar.gz
 COPY docker/start.sh .
 
-# Copy the locally built WAR file instead of downloading
-# Note: Build the project first with 'mvn clean package' from the root directory
-COPY atomhopper/target/atomhopper-*.war atomhopper.war
+# Copy the WAR file from the builder stage
+COPY --from=builder /app/atomhopper/target/atomhopper-*.war atomhopper.war
 
 RUN rm -rf ${CATALINA_HOME}/webapps/* \
     && mkdir -p ${CATALINA_HOME}/webapps \