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== How To Test ==
== How To Test ==
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Build and push container images to container registries. Inspect them to check that their format is zstd:chunked.  Pull the image back to the host.  Now make a small change to the image and push it back to the registry
 
Remove the changed image leaving the original image in place. Now pull the updated image again. You should see a big change in download speed.
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A good "how to test" should answer these four questions:
 
0. What special hardware / data / etc. is needed (if any)?
1. How do I prepare my system to test this change? What packages
need to be installed, config files edited, etc.?
2. What specific actions do I perform to check that the change is
working like it's supposed to?
3. What are the expected results of those actions?
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Now attempt to pull the same image with Docker/Moby to make sure the image works with those container engines.


== User Experience ==
== User Experience ==

Revision as of 15:54, 31 October 2023


Change Proposal Name

This is a proposed Change for Fedora Linux.
This document represents a proposed Change. As part of the Changes process, proposals are publicly announced in order to receive community feedback. This proposal will only be implemented if approved by the Fedora Engineering Steering Committee.

Summary

Modify podman push to default to creating images with zstd:chunked, allowing users to modify containers.conf to continue to use the legacy gzip image format.

Owner

Current status

  • Targeted release: Fedora Linux 40
  • Last updated: 2023-10-31
  • [<will be assigned by the Wrangler> devel thread]
  • FESCo issue: <will be assigned by the Wrangler>
  • Tracker bug: <will be assigned by the Wrangler>
  • Release notes tracker: <will be assigned by the Wrangler>

Detailed Description

The goal is to speed up the pulling of container images, via using zstd:chunked. zstd:chunked format has shown itself to speed up the pulling of images by as much as 90%. This change has been waiting for change for over 3 years, waiting for Docker to support the format.

Feedback

Benefit to Fedora

Fedora would be the first distribution to support building zstd:chunked format by default. Container engines (Podman, Buildah, Skopeo, CRI-O) which support the format natively would see a great speed up in pulling images. Other container engines including Docker and Containerd would see some speed up do the the compression algorythms of zstd, but not to the same degree as container engines with full support.

Scope

  • Proposal owners:
  • Other developers:
  • Policies and guidelines: N/A (not needed for this Change)
  • Trademark approval: N/A (not needed for this Change)
  • Alignment with Community Initiatives:

Upgrade/compatibility impact

How To Test

Build and push container images to container registries. Inspect them to check that their format is zstd:chunked. Pull the image back to the host. Now make a small change to the image and push it back to the registry Remove the changed image leaving the original image in place. Now pull the updated image again. You should see a big change in download speed.

Now attempt to pull the same image with Docker/Moby to make sure the image works with those container engines.

User Experience

Dependencies

Contingency Plan

  • Contingency mechanism: (What to do? Who will do it?) N/A (not a System Wide Change)
  • Contingency deadline: N/A (not a System Wide Change)
  • Blocks release? N/A (not a System Wide Change), Yes/No


Documentation

N/A (not a System Wide Change)

Release Notes

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