Containerization has become a foundational practice in modern software development. By packaging applications together with their dependencies, containers ensure consistency across development, testing, and production environments. For .NET developers, Docker provides a powerful and flexible way to deploy web applications efficiently.

This article provides a deep, end‑to‑end guide on how to containerize a .NET 10 web application using Docker. We will explore Docker fundamentals, multi‑stage builds for optimized images, Docker Init for fast scaffolding, and Docker Compose for managing multi‑container setups. All examples are practical and production‑oriented, and the article concludes with a comprehensive summary of best practices and lessons learned.

Understanding Containerization And Docker In The .NET Ecosystem

Containerization allows applications to run in isolated environments called containers. Each container includes the application code, runtime, libraries, and configuration files it needs to run. Unlike virtual machines, containers share the host operating system kernel, making them lightweight and fast.

Docker is the most widely adopted container platform. In the .NET ecosystem, Docker integrates seamlessly with the .NET SDK and runtime images, enabling developers to build, test, and deploy applications consistently across different environments. With .NET 10 continuing Microsoft’s emphasis on performance, cloud‑native design, and minimal APIs, Docker becomes an essential deployment tool rather than an optional add‑on.

Prerequisites And Project Setup

Before containerizing a .NET 10 web application, ensure the following tools are installed:

• .NET 10 SDK
• Docker Desktop or Docker Engine
• A code editor such as Visual Studio or Visual Studio Code

Create a new .NET 10 web application using the CLI:

Run the application locally to confirm it works:

At this stage, the application runs directly on your machine. The goal of containerization is to make it run identically inside Docker.

Writing A Basic Dockerfile For A .NET 10 Application

A Dockerfile defines how a Docker image is built. A basic Dockerfile for a .NET application includes the runtime image, copies the application files, and starts the application.

While this works, it has several drawbacks:

• It includes unnecessary SDK files if built incorrectly
• It produces a larger image
• It is not optimized for build caching

To address these issues, we use multi‑stage builds.

Using Multi‑Stage Builds For Optimized Docker Images

Multi‑stage builds allow you to use multiple base images in a single Dockerfile. One stage handles building the application, while another runs the compiled output. This results in smaller, more secure images.

A production‑ready Dockerfile for a .NET 10 web app looks like this:

Key advantages of this approach include:

• Smaller image size
• Faster builds through layer caching
• Separation of build and runtime concerns
• Reduced attack surface

This is the recommended approach for nearly all production .NET container deployments.

Leveraging Docker Init For Rapid Containerization

Docker Init is a relatively new feature designed to simplify container setup. It analyzes your project and generates Docker‑related files automatically.

Run the following command in your project directory:

Docker Init will prompt you for configuration details such as:

• Application platform (.NET)
• Port number
• Whether to include Docker Compose

Once completed, Docker Init generates:

• A Dockerfile optimized for .NET
• A .dockerignore file
• Optionally, a docker‑compose.yml file

This approach is ideal for teams that want a fast and standardized starting point without writing everything manually.

Understanding And Customizing The Generated Dockerfile

The Dockerfile generated by Docker Init is typically already multi‑stage and follows best practices. However, it should still be reviewed and customized.

Common improvements include:

• Adding environment variables
• Adjusting exposed ports
• Enabling globalization or time zone support
• Configuring health checks

Example customization:

These small changes make the container more predictable and production‑ready.

Using Docker Compose For Multi‑Container Applications

Most real‑world applications depend on more than one service. Docker Compose allows you to define and manage multi‑container applications using a single YAML file.

Create a docker-compose.yml file:

Docker Compose simplifies local development, integration testing, and onboarding by allowing developers to start the entire stack with one command.

Running And Testing The Application With Docker

Build and run the containers using:

Docker will:

• Build the .NET application image
• Start the web container
• Start the database container
• Connect them using an internal network

Access the application at:

Logs from all services are streamed to the console, making debugging straightforward.

Environment Configuration And Secrets Management

Avoid hardcoding sensitive data in Dockerfiles or Compose files. Instead:

• Use environment variables
• Use .env files for local development
• Use secret managers in production environments

Example .env file:

Docker Compose automatically loads variables from this file, keeping configurations clean and flexible.

Performance And Security Considerations

When containerizing .NET 10 applications, consider the following best practices:

• Use slim runtime images
• Run containers as non‑root users when possible
• Enable HTTPS termination at a reverse proxy
• Use health checks to monitor container status
• Keep base images updated

Example health check:

These practices improve reliability, observability, and security in production deployments.

Conclusion

Containerizing .NET 10 web applications with Docker is no longer a niche skill—it is a core competency for modern .NET developers. Through this article, we explored the complete containerization journey, starting from fundamental concepts and moving toward production‑grade implementations.

We began by understanding why containerization matters and how Docker fits naturally into the .NET ecosystem. We then created a .NET 10 web application and examined a basic Dockerfile, highlighting its limitations. This naturally led to the adoption of multi‑stage builds, which dramatically improve image size, performance, and security by separating the build and runtime environments.

Docker Init was introduced as a productivity‑boosting tool that accelerates setup while enforcing best practices. Rather than replacing understanding, it serves as a strong foundation that developers can customize to meet their specific needs. We also explored Docker Compose, which enables seamless orchestration of multi‑container systems and simplifies local development and testing workflows.

Beyond simply getting containers to run, we addressed real‑world concerns such as environment configuration, secrets management, performance tuning, and security hardening. These considerations are what transform a working container into a reliable, scalable, and production‑ready deployment unit.

Ultimately, Docker empowers .NET 10 applications to be portable, consistent, and cloud‑native. By mastering multi‑stage builds, leveraging Docker Init, and orchestrating services with Docker Compose, developers gain full control over how their applications are built, shipped, and run. This approach reduces friction across teams, minimizes deployment surprises, and lays a strong foundation for future scalability and modernization.

As .NET continues to evolve toward leaner, faster, and more cloud‑optimized frameworks, containerization with Docker remains one of the most effective ways to unlock its full potential.