Courses & Projects by Rob Marano

Week 05: Containerization Lab - TCP Server

This lab demonstrates how to containerize the Java TCP Server created in the previous weeks using Docker.

Prerequisites

• Docker Desktop installed and running.
• Java Development Kit (JDK) 21.

Project Structure

• src/TCPServer.java: The multi-threaded TCP Server source code.
• src/TCPClient.java: The TCP Client source code.
• Dockerfile: Instructions to build the Docker image for the server.
• entrypoint.sh: The script executed when the Docker container starts.
• Makefile: Script to compile and run the Java code locally.

Step 1: Compile the Java Code Locally

Before building the Docker image, compile the Java source code to generate the .class files in the bin/ directory.

make compile

This will create bin/TCPServer.class and bin/TCPServer$ClientHandler.class.

Step 2: Build the Docker Image

Build the Docker image using the provided Dockerfile. We will tag the image as transcriptor:v1.

docker build -t transcriptor:v1 .

Note: The Dockerfile relies on Ubuntu 24.10, installs Headless OpenJDK 21, and copies the .class files from the bin/ directory into the image.

Step 3: Run the Docker Container

Run the Docker container in detached mode (-d), mapping port 12345 on your host machine to port 12345 inside the container.

docker run -d -p 12345:12345 --name tcp-server-container transcriptor:v1

Verify the container is running:

docker ps

Step 4: Connect the Local Client

Run the TCP Client locally to connect to the Dockerized server.

# Compile if you haven't already
make compile

# Run the client
java -cp bin TCPClient

Type messages into your terminal. You should see them echoed back by the server running securely inside the Docker container. Type exit to close the client connection.

Step 5: Clean Up

Stop and remove the running Docker container:

docker stop tcp-server-container
docker rm tcp-server-container

Remove the compiled .class files:

make clean

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