Building Container Images with Buildpacks

When it comes to containerization, Docker has been the de facto standard for building and deploying container images. However, Buildpacks offer a compelling alternative, simplifying many aspects of the containerization process. In this article, we’ll explore what Buildpacks are, their advantages and disadvantages, and how to use them in practical scenarios. We’ll illustrate this by containerizing a Go application named golang-response-echoer, which acts as a versatile server responding to various HTTP requests.

What are Buildpacks?

Buildpacks are a cloud-native technology that turns code into container images without the need for a Dockerfile. Originally developed by Heroku and later contributed to the Cloud Native Computing Foundation (CNCF), Buildpacks abstract away the complexities of building container images, allowing developers to focus on code rather than the nuances of containerization.

Official web site

Pros of Buildpacks:

• Simplicity: Buildpacks require no Dockerfile. Developers can build container images with minimal knowledge of the underlying containerization platform.
• Efficiency: They automatically detect the necessary dependencies and runtime for your application, optimizing the build process.
• Consistency: Buildpacks provide consistent environments, ensuring that your applications run the same way in development, testing, and production.
• Portability: The images created are OCI-compliant, meaning they can be run by any runtime that supports the Open Container Initiative, such as Docker and Kubernetes.
• Security: Buildpacks often come with hardened base images and can be configured to include only what is necessary, reducing the attack surface of your containers.

Cons of Buildpacks:

• Less Control: The abstraction comes at the cost of detailed control over the image configuration, which can be limiting if specific tweaks are necessary.
• Learning Curve: Understanding how Buildpacks work and how to configure them for non-standard requirements can involve a learning curve.
• Tooling Compatibility: Some specific tooling or scripts designed for Docker might not be directly compatible with Buildpacks.

When to Use Buildpacks Instead of Docker or Other Tools?

Buildpacks are particularly useful in development environments where speed and simplicity are more critical than intricate configuration. They are also beneficial in organizations looking to enforce certain security standards or consistency across many applications without delving into Dockerfile maintenance.

Practical Application: Containerizing a Go Server

To demonstrate how Buildpacks can be used in practice, we will take a simple Go server application designed to respond dynamically to HTTP requests. The server showcases various responses based on the query parameters or headers it receives.

Instead of detailing the commands here, I’ve prepared a Github repo that guides you through the steps of using the Pack CLI tool to containerize this Go application. This includes preparing your application, building the image, and running the container effectively.

# List suggested builders
pack builder suggest

Output:

Suggested builders:
	Google:                gcr.io/buildpacks/builder:v1                            Ubuntu 18 base image with buildpacks for .NET, Go, Java, Node.js, and Python
	Heroku:                heroku/builder:20                                       Heroku-20 (Ubuntu 20.04) base image with buildpacks for Go, Java, Node.js, PHP, Python, Ruby & Scala.
	Heroku:                heroku/builder:22                                       Heroku-22 (Ubuntu 22.04) base image with buildpacks for Go, Java, Node.js, PHP, Python, Ruby & Scala.
	Paketo Buildpacks:     paketobuildpacks/builder-jammy-base                     Ubuntu 22.04 Jammy Jellyfish base image with buildpacks for Java, Go, .NET Core, Node.js, Python, Apache HTTPD, NGINX and Procfile
	Paketo Buildpacks:     paketobuildpacks/builder-jammy-buildpackless-static     Static base image (Ubuntu Jammy Jellyfish build image, distroless-like run image) with no buildpacks included. To use, specify buildpacks at build time.
	Paketo Buildpacks:     paketobuildpacks/builder-jammy-full                     Ubuntu 22.04 Jammy Jellyfish full image with buildpacks for Apache HTTPD, Go, Java, Java Native Image, .NET, NGINX, Node.js, PHP, Procfile, Python, and Ruby
	Paketo Buildpacks:     paketobuildpacks/builder-jammy-tiny                     Tiny base image (Ubuntu Jammy Jellyfish build image, distroless-like run image) with buildpacks for Java, Java Native Image and Go

Tip: Learn more about a specific builder with:
	pack builder inspect <builder-image>

Conclusion

Buildpacks provide a streamlined, efficient way to build container images, especially when rapid development and deployment cycles are crucial. They can significantly simplify the DevOps pipeline, though they may not fit every scenario, particularly where deep customization of the build environment is needed. By incorporating Buildpacks into your workflow, you can reduce the overhead related to Dockerfile maintenance and focus more on developing your applications.

Building Container Images with Buildpacks