Docker has revolutionized the way we build, ship, and deploy applications by providing a consistent environment encapsulated in containers. One of the key challenges when containerizing applications is to strike a balance between security, size, and functionality. Multistage builds and the use of distroless images are two powerful techniques that can help achieve this balance. In this blog post, we'll delve into the concept of multistage Dockerization and explore how combining it with distroless images can enhance security and efficiency in your containerized applications.
Understanding Multistage Dockerization
Multistage Docker builds are a technique used to optimize container image size, improve run time performance, allow for better organization of Docker commands and files, and provide a standardized method of running build actions. while still providing a secure and functional runtime environment. This approach involves using multiple Docker images in the build process, each with a specific purpose. The idea is to utilize a larger, fully-featured base image in the first stage to compile and build the application, and then transfer only the necessary artifacts to a smaller base image in the final stage for runtime.
The key benefits of multistage Dockerization include:
Reduced Image Size: By discarding unnecessary build artifacts and dependencies, the final image size is significantly reduced. This is crucial for efficient image distribution and quicker deployment times.
Minimized Attack Surface: The use of multiple stages allows you to eliminate unnecessary components, reducing the attack surface of your container. This enhances the security of your application.
Improved CI/CD Pipelines: Smaller image sizes lead to faster build and deployment times, enabling more streamlined and efficient CI/CD pipelines.
What are Distroless Images?
Distroless images take the idea of minimalism to the next level by providing container images with only the essential runtime components required for running an application. Distroless container images come with no package manager, shell, and other programs that come with a typical OS container image, thereby not only reducing unnecessary code but reducing attack surface with it. Distroless images are highly specialized and designed for specific programming languages, such as Java, Go, Python, and Node.js.
Why its required?
There are many advantages of having distroless image.
Help to run the application with required binaries and libraries
No package manager, shell and other programs
Size of the docker images can be reduced drastically
Secure the images without vulnerabilities
Best practice for the production environments
How it can be achieved?
Configure the Dockerfile to use multi-stage builds
Identify the libraries, and run time binaries required for the application to work
Build and copy the code, and required programs to the final distroless image
Combining Multistage Builds with Distroless Images
When combining multistage builds with distroless images, you're maximizing the advantages of both techniques. Here's how you can go about it:
First Stage: In the initial stage, use a base image that includes the necessary build tools for your application's language or framework. Compile and build your application here, but keep it as minimal as possible.
Second Stage: In the final stage, switch to a distroless image tailored for your application's runtime environment. Copy only the compiled artifacts from the first stage to the second stage. Since the distroless image contains only the runtime essentials, your final container image will be incredibly small and secure.
Runtime Configuration: If your application requires any configuration or environment variables, you can set them in the second stage using mechanisms provided by your chosen runtime language or framework.
Example :
You can check my repo https://github.com/messaoudimaher/Multistage_Dockerization_with_Distroless.git
a simple Golang application and presenting 2 different parts: the basic dockerization and the multistage dockerization
go run calculator.go
docker build -t simplecalculat-multistage .
