Describe the Problem

Per the supported platforms policy, .NET images for the previous version of Alpine are published for three months after the new version is released.

Alpine 3.24 images were added to main on July 1, 2026 in #7263, and announced as available on July 2, 2026. Alpine floating tags were updated to reference Alpine 3.24 with the August 11, 2026 servicing release.

Describe the Solution

Stop publishing Alpine 3.23 images on October 13, 2026 (October Patch Tuesday), three months after Alpine 3.24 image availability, aligned with the October servicing release. This follows the timing used for Alpine 3.22 retirement in #6861.

Remove Alpine 3.23 from the supported build matrix and tag listings for .NET 8, 9, and 10, including associated Dockerfiles, manifest entries, templates, and test coverage. .NET 11 preview images already replaced Alpine 3.23 with Alpine 3.24.

Announce the cutoff and direct users of version-specific Alpine 3.23 tags to Alpine 3.24. Existing published Alpine 3.23 tags and images should remain pullable, but receive no further updates, consistent with the tag lifecycle policy.

Additional Context

Previous tracking issues:

• Stop publishing Alpine 3.22 images #6861: Stop publishing Alpine 3.22 images
• Remove Alpine 3.20 Dockerfiles #6285: Remove Alpine 3.20 Dockerfiles
• Remove Alpine 3.19 Dockerfiles #5799: Remove Alpine 3.19 Dockerfiles