🐳 How to Create Dockerfile for React.js, Java, and .NET Applications

This note explains how to write Dockerfiles for different types of applications — React.js, Java, and .NET — so they can run inside Docker containers.

⚛️ React.js Dockerfile

React is a front-end framework built with Node.js, so we use a Node base image to build and serve the app.

Example Dockerfile:

# Step 1: Build the React app
FROM node:18-alpine AS build
WORKDIR /app
COPY package*.json ./
RUN npm install
COPY . .
RUN npm run build

# Step 2: Serve the app using Nginx
FROM nginx:alpine
COPY --from=build /app/build /usr/share/nginx/html
EXPOSE 80
CMD ["nginx", "-g", "daemon off;"]

Explanation:

• The first stage installs dependencies and builds the React app.
• The second stage serves the static build using Nginx.
• This multi-stage build reduces image size and improves performance.

☕ Java (Spring Boot) Dockerfile

For Java apps (especially Spring Boot), we use a base image with OpenJDK.

Example Dockerfile:

# Use an OpenJDK base image
FROM openjdk:17-jdk-slim
WORKDIR /app

# Copy the jar file (generated from mvn package or gradle build)
COPY target/myapp.jar /app/myapp.jar

# Expose the application port
EXPOSE 8080

# Run the Java application
ENTRYPOINT ["java", "-jar", "myapp.jar"]

Explanation:

• The COPY command copies your built .jar file into the container.
• The container runs java -jar myapp.jar when started.
• Exposes port 8080 for web access.

⚙️ .NET (ASP.NET Core) Dockerfile

For .NET Core web applications, we use Microsoft’s official .NET SDK and runtime images.

Example Dockerfile:

# Step 1: Build the .NET app
FROM mcr.microsoft.com/dotnet/sdk:8.0 AS build
WORKDIR /source
COPY . .
RUN dotnet restore
RUN dotnet publish -c Release -o /app/publish

# Step 2: Run the published app
FROM mcr.microsoft.com/dotnet/aspnet:8.0
WORKDIR /app
COPY --from=build /app/publish .
EXPOSE 80
ENTRYPOINT ["dotnet", "MyApp.dll"]

Explanation:

• The build stage compiles the .NET project and publishes it to a folder.
• The runtime stage uses a lightweight image to run the app.
• Exposes port 80 for the web server.