Add DevSecOpsApp code with updated Jenkins pipeline for multi-environment deployment

frontend/Dockerfile

@@ -0,0 +1,47 @@
+# Multi-stage build for React frontend
+FROM node:18-alpine AS build
+
+# Set working directory
+WORKDIR /app
+
+# Copy package files
+COPY package*.json ./
+
+# Install dependencies
+RUN npm ci
+
+# Copy source code
+COPY public/ ./public/
+COPY src/ ./src/
+
+# Build the application
+RUN npm run build
+
+# Production stage with Nginx
+FROM nginx:alpine AS production
+
+# Copy custom nginx config
+COPY nginx.conf /etc/nginx/nginx.conf
+
+# Copy built React app
+COPY --from=build /app/build /usr/share/nginx/html
+
+# Create a non-root user for nginx
+RUN addgroup -g 1001 -S nginxgroup && \
+    adduser -S nginxuser -u 1001 -G nginxgroup
+
+# Change ownership of nginx directories
+RUN chown -R nginxuser:nginxgroup /var/cache/nginx && \
+    chown -R nginxuser:nginxgroup /var/log/nginx && \
+    chown -R nginxuser:nginxgroup /etc/nginx/conf.d && \
+    chown -R nginxuser:nginxgroup /usr/share/nginx/html
+
+# Health check
+HEALTHCHECK --interval=30s --timeout=3s --start-period=5s --retries=3 \
+  CMD wget --no-verbose --tries=1 --spider http://localhost:80/ || exit 1
+
+# Expose port
+EXPOSE 80
+
+# Start nginx
+CMD ["nginx", "-g", "daemon off;"]