docker file update

Dockerfile

@@ -1,20 +1,35 @@
 # Use an official Node runtime as the parent image
-FROM node:18
+FROM node:18-slim
 
-# Set the working directory in the container
+# Create app directory
 WORKDIR /usr/src/app
 
-# Copy package.json and package-lock.json
+# Install app dependencies
+# A wildcard is used to ensure both package.json AND package-lock.json are copied
 COPY package*.json ./
 
 # Install dependencies
-RUN npm install
+RUN npm ci --only=production
 
-# Copy the rest of your app's source code
+# Bundle app source
 COPY . .
 
-# Your app binds to port 3000 so you'll use the EXPOSE instruction to have it mapped by the docker daemon
+# Create a non-root user
+RUN addgroup --system --gid 1001 nodejs && \
+    adduser --system --uid 1001 --ingroup nodejs nodejs && \
+    chown -R nodejs:nodejs /usr/src/app
+
+USER nodejs
+
+# Your app binds to port 3000
 EXPOSE 3000
 
-# Define the command to run your app
+# Add healthcheck
+HEALTHCHECK --interval=30s --timeout=3s \
+  CMD curl -f http://localhost:3000/health || exit 1
+
+# Define environment variable
+ENV NODE_ENV=production
+
+# Start the app
 CMD [ "node", "index.js" ]