Use a Maven POM to fetch backend JAR

.github/workflows/docker-image.yml

@@ -18,6 +18,6 @@ jobs:
         distribution: 'temurin'
         cache: maven
     - name: Download the backend JAR
-      run: ./download-backend.sh
+      run: mvn -B dependency:copy-dependency -DexcludeTransitive=true
     - name: Build the Docker image
-      run: docker build . --file Dockerfile --tag playground-docker:$(date +%s)
+      run: docker build --tag playground-docker:$(date +%s) .

pom.xml

@@ -0,0 +1,25 @@
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+
+    <groupId>org.eclipse.epsilon.labs.playground</groupId>
+    <artifactId>playground-docker</artifactId>
+    <version>1.0-SNAPSHOT</version>
+    <packaging>pom</packaging>
+
+    <properties>
+        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+        <java.version>17</java.version>
+    </properties>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.eclipse.epsilon.labs.playground.micronaut</groupId>
+            <artifactId>http-server</artifactId>
+            <version>0.1-SNAPSHOT</version>
+            <classifier>all</classifier>
+        </dependency>
+    </dependencies>
+
+</project>