Alternative Docker images based on Ubuntu and Alpine

[lolgab]

It would be nice to have alternative official docker images that run on Ubuntu and Alpine, which are two of the most used base images.

[thresheek]

Hi @lolgab!

I'm not sure Ubuntu-ones are warranted since Debian-based ones are ubiquitous in Docker official images.

Regarding Alpine, this is worth exploring. Maybe language variants will be smaller than what's provided by current Debian-based images.

[thresheek]

See also #777

[crabique]

The problem with Alpine is that Unit needs the embed SAPI, but it's not enabled in the cli flavor (at least the NTS one), and the maintainers of the official images are not in favor of the image size increase.

I agree Alpine/Unit official image would be awesome, but this would require the PHP image maintainers to either create a new sapi flavor or add the embed SAPI into the cli flavor, the rest should be fairly straightforward.