DevConf.CZ 2026

Stop Re-Downloading Your Container Images: Content-Based Layers with Chunkah
2026-06-18 , D0206 (capacity 154)

Update one package in your container image and watch your users re-download 500MB of unchanged content. Traditional Dockerfile layers are instruction-based—a single package update invalidates an entire layer.

This talk introduces chunkah, a tool that post-processes container images into content-based layers. Files are grouped by package, not Dockerfile structure. Update one package, users download only that layer.

We'll cover:

  • Why instruction-based layers hurt pull performance (with numbers)
  • How content-based splitting works under the hood
  • Live demo: chunkah in action, before/after comparison
  • How podman history reveals package-to-layer mapping

From Project Hummingbird, where we run 70+ production container images with chunkah, we'll show real metrics on bandwidth savings and how to adopt this in your own builds.

Audience: Container image builders, CI/CD engineers, registry operators, anyone who's wondered why their image pulls are so slow.


Experience level: Intermediate - attendees should be familiar with the subject
See also:

As the Senior Engineering Manager for Red Hat CoreOS, Clément Verna believes that the best software is built by empowered, well-connected teams. From mastering the nuances of Kubernetes to pioneering bootc workflows, Clément is dedicated to making open-source infrastructure more accessible and scalable. He thrives on helping his team and the broader community achieve technical excellence through a culture of growth and shared learning.

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