Why Cloud Native Buildpacks Are Revolutionizing Container Image Building

Introduction

Cloud native is reshaping software development; containers replace traditional build processes and developers now need to create Dockerfiles to containerise applications, ensuring reliability and efficiency. Operations teams focus on image security and standardisation, asking questions such as which base image to use, dependency versions, and required ports.

Cloud Native Buildpacks (CNB)

CNB, a CNCF‑incubated project, offers a modular way to build OCI‑compliant images, decoupling development and operations. It originated from Heroku in 2011, was adopted by Cloud Foundry, and later promoted by Pivotal and Heroku as a CNCF sandbox project before graduating to incubation.

Why CNB?

Eliminates repetitive Dockerfile creation by using a single Builder.

Removes direct Dockerfile dependency.

Provides transparent metadata via buildpack.toml.

Works across OS changes without rewriting build logic.

Ensures security and compliance without developer intervention.

CNB also supports advanced cloud‑native features such as cross‑registry blob mounting and image layer rebasing.

Key Concepts

Buildpack

A buildpack converts source code into a runnable artifact (droplet). It typically contains three files: buildpack.toml (metadata), bin/detect (detects applicability), and bin/build (executes the build).

Builder

A Builder is a collection of Buildpacks plus a Lifecycle and a Stack. It defines the environment (build image) and the runtime base (run image) used to produce the final app image.

Stack

A Stack combines a build image and a run image, analogous to multi‑stage Docker builds, providing the foundation for both building and running the application.

Lifecycle

The Lifecycle orchestrates the Buildpack process in four phases:

Detect : Executes each Buildpack’s /bin/detect to decide which Buildpacks apply.

Analysis : Determines layer handling (launch, build, cache).

Build : Runs the selected Buildpacks to generate the app image.

Export : Produces an OCI‑compatible image.

Rebase : Swaps the run image without rebuilding the app, simplifying OS upgrades.

type BuildPlanEntry struct {
    Providers `toml:"providers"`
    Requires  `toml:"requires"`
}

Platform

The Platform (e.g., Tekton or the pack CLI) executes the Lifecycle, applying a Builder to source code to create the final image.

Using Pack CLI

Install Pack on Ubuntu:

$ sudo add-apt-repository ppa:cncf-buildpacks/pack-cli
$ sudo apt-get update
$ sudo apt-get install pack-cli

Verify version:

$ pack version
0.22.0+git-26d8c5c.build-2970

Create a Builder from a builder.toml configuration (example shown in the article) and then build an app:

$ pack builder create cnbs/sample-builder:bionic --config builder.toml
$ pack build --path apps/java-maven --builder cnbs/sample-builder:bionic sample-app

Run the resulting image with Docker:

$ docker run -it -p 8080:8080 sample-app

Summary

Cloud Native Buildpacks provide a higher‑level abstraction for image construction, improving security, standardisation, and maintainability compared to traditional Dockerfiles. While large organisations may need to adapt CI/CD pipelines or create custom Builders, the long‑term benefits include reduced maintenance effort and faster, more reliable deployments.