solved lab. AM

java-k8s-lab/Dockerfile

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+# --------- Build Stage ---------
+FROM adoptopenjdk:11 as build
+WORKDIR /app
+
+# Copy the Java source file into the container
+COPY HelloController.java .
+
+# Compile the Java source file
+RUN javac HelloController.java
+
+# Package all compiled classes (including inner classes) into an executable jar
+RUN jar cfe app.jar HelloController *.class
+
+# --------- Run Stage ---------
+FROM adoptopenjdk:11-jre-hotspot
+WORKDIR /app
+
+# Copy the executable jar from the build stage
+COPY --from=build /app/app.jar .
+
+# Expose the port on which the app listens
+EXPOSE 8080
+
+# Run the jar file
+ENTRYPOINT ["java", "-jar", "app.jar"]

java-k8s-lab/HelloController.java

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+import com.sun.net.httpserver.HttpServer;
+import com.sun.net.httpserver.HttpHandler;
+import com.sun.net.httpserver.HttpExchange;
+import java.io.IOException;
+import java.io.OutputStream;
+import java.net.InetSocketAddress;
+
+public class HelloController {
+    public static void main(String[] args) throws IOException {
+        HttpServer server = HttpServer.create(new InetSocketAddress(8080), 0);
+        server.createContext("/", new MyHandler());
+        server.setExecutor(null);
+        server.start();
+        System.out.println("Server started on port 8080...");
+    }
+
+    static class MyHandler implements HttpHandler {
+        @Override
+        public void handle(HttpExchange t) throws IOException {
+            String response = "Hello, Kubernetes!";
+            t.sendResponseHeaders(200, response.length());
+            try (OutputStream os = t.getResponseBody()) {
+                os.write(response.getBytes());
+            }
+        }
+    }
+}

java-k8s-lab/deployment.yaml

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+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: java-app-deployment
+spec:
+  replicas: 1
+  selector:
+    matchLabels:
+      app: java-app
+  template:
+    metadata:
+      labels:
+        app: java-app
+    spec:
+      containers:
+      - name: java-app-container
+        image: aminmoh9/my-java-app:1.0
+        ports:
+        - containerPort: 8080

java-k8s-lab/service.yaml

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+apiVersion: v1
+kind: Service
+metadata:
+  name: java-app-service
+spec:
+  type: NodePort
+  selector:
+    app: java-app
+  ports:
+    - protocol: TCP
+      port: 80         # The service port
+      targetPort: 8080 # Container's port
+      nodePort: 30081  # Node port (optional)