Drop image for Ubuntu 16.04 LTS (end of standard support)

[dpward]

Ubuntu 16.04 LTS reached the end of standard support in April 2021. Updates are only provided through Extended Security Maintenance (ESM) which must be purchased from Canonical¹. The latest publicly-available version of Ubuntu 16.04 LTS is affected by 343 CVEs.

This image should be dropped out of security concerns. Base images are available for Ubuntu 18.04 LTS and 20.04 LTS, which remain under standard support.

Footnotes

1. ESM is free for personal use on up to 3 systems. For use on GCP or other public clouds, Ubuntu Pro is a paid image that includes ESM. ↩