Migrate away from deprecated `heroku/buildpacks:20` and `heroku/builder-classic:22` CNB builder images

[edmorley]

Hi 👋

This project uses Heroku's heroku/buildpacks:20 and heroku/builder-classic:22 CNB builder images:
https://github.com/search?q=repo%3Aporter-dev%2Fporter+%28%22heroku%2Fbuilder-classic%3A22%22+OR+%22heroku%2Fbuildpacks%3A20%22%29&type=code

We have deprecated this builder image as of heroku/cnb-builder-images#429.

Please migrate to heroku/builder:22 or heroku/builder:20, to continue to receive security updates, and to avoid disruption when the build time deprecation warning is upgraded to an error in the future.

More information on the difference between the various builder images can be seen here:
https://github.com/heroku/cnb-builder-images#heroku-cnb-builder-images

I also see there are references to the even older (and EOL/insecure) heroku/buildpacks:18 - these need to be migrated too:
https://github.com/search?q=repo%3Aporter-dev%2Fporter+%22heroku%2Fbuildpacks%3A18%22&type=code

The docs here will also need updating:
https://github.com/search?q=repo%3Aporter-dev%2Fdocs+%22heroku%2Fbuildpacks%22&type=code

[jose-fully-ported]

Hi @edmorley, I'll reach out to you on the CNCF slack :)

[edmorley]

@jose-fully-ported Gentle nudge that Porter is still using these deprecated images - builds using these images will start erroring in the future (likely in the next couple of months; there will be an env var opt out), and the underlying images will stop receiving security updates.

[edmorley]

@jose-fully-ported @ferozemohideen @stefanmcshane ^

[edmorley]

and to avoid disruption when the build time deprecation warning is upgraded to an error in the future.

This will be happening within the next couple of weeks in heroku/cnb-builder-images#474. We'll be adding an env var override for the errors, but I strongly recommend you switch from heroku/buildpacks:20 and heroku/builder-classic:22 to heroku/builder:* as soon as possible.

[edmorley]

Please migrate to heroku/builder:22 or heroku/builder:20, to continue to receive security updates, and to avoid disruption when the build time deprecation warning is upgraded to an error in the future.

The deprecation warnings were upgraded to errors this morning:
heroku/cnb-builder-images#478

[edmorley]

It looks like the errors were suppressed for this project in #4420, which is not what I'd recommend.

End users need to be made aware of this change, and so ideally they should be the ones setting the env var themselves.

[edmorley]

As of yesterday, the legacy heroku/buildpacks:20 and heroku/builder-classic:22 builder images are no longer updated, and so won't receive security updates, fixes or support for new language runtime version releases. Please switch to using the heroku/builder:* images instead:
https://github.com/heroku/cnb-builder-images#available-images