Revert "Remove non-assignment 4 code"

This reverts commit 44f2724.

Author: szelongq

ChatService/Dockerfile

@@ -0,0 +1,20 @@
+# Use an official Node.js runtime as a parent image
+FROM node:14
+
+# Set the working directory in the container
+WORKDIR /usr/src/chat-service
+
+# Copy package.json and package-lock.json to the working directory
+COPY package.json ./
+
+# Install app dependencies
+RUN npm install
+
+# Bundle your app source code into the container
+COPY . .
+
+# Expose the port on which your Chat service will run
+EXPOSE 3007
+
+# Define the command to start your Chat service
+CMD [ "npm", "run", "dev"]