Add Ubuntu images

[unikitty37]

I'm trying to use the ruby images to run an application that uses the image_processing gem with libvips. Unfortunately, image_processing requires libvips 8.6.0 or higher, and stretch only provides 8.4.5. I can't use the alpine images, as other dependencies aren't available for it. There's a hard requirement to not install ImageMagick, so I have to use libvips.

There is no PPA for libvips, my attempts to build from source in the Dockerfile have not produced anything that actually works under GitLab CI, and the instructions at https://renchap.com/blog/post/building_recent_libvips_on_debian/ seem to be out-of date, and don't work.

There is a sufficiently recent version of libvips in buster, but I can't see any sign that it will be released any time soon (and, quite correctly, there are no plans to release an image based on the Debian unstable release — see #224).

Ubuntu 18.10 does provide an up-to-date version of libvips, and would allow me to get things up and running without having to wait (possibly many) months for a new Debian release.

Are there any plans to add Ubuntu images at all?

Thanks :)

[tianon]

Not officially (see #247 for a recent example of this same discussion).

For the most part, I imagine you'd be able to take the Dockerfile of the particular version+variant you're interested that we maintain as-is and simply swap the FROM to an Ubuntu base instead and it will very likely work without or with very minimal changes.

[TimWolla]

There is a sufficiently recent version of libvips in buster, but I can't see any sign that it will be released any time soon

You can attempt to use apt pinning to pull in just that library from buster. See PHP: https://github.com/docker-library/php/blob/0f189799b756321f6ea311b61335db69650b268d/7.3/stretch/fpm/Dockerfile#L120-L128

[unikitty37]

Thanks, @TimWolla — I'd completely forgotten about apt pinning 😁