Changes in test and Dockerfile

[JJ]

• Changes in the Dockerfile use "latest" version instead of having to change the last version manually from time to time. Since documentation says by default it builds the latest version, it iw consistent with it.
• Minor changes in documentation.
• The Travis file builds, starts and then checks it's running. Maybe it would be better to have a test suite and actually run it, but this is second best.

[hoelzro]

Hi @JJ, thanks for the contribution! Quick question: wouldn't having ARG rakudo_version=latest cause docker to cache the resulting image, so you would need to invalidate the cache every time you want to build an image for a new rakudo star version?

[tianon]

@hoelzro correct -- for the official images builds, this will need to stay pinned to a specific version, but perhaps some documentation could be added to this repo about using latest via --build-arg? (or a quick link for how to look up what the latest release version is, and then how to specify it?)

[JJ]

2017-12-08 21:30 GMT+01:00 Tianon Gravi notifications@github.com:

@hoelzro https://github.com/hoelzro correct -- for the official images builds, this will need to stay pinned to a specific version, but perhaps some documentation could be added to this repo about using latest via --build-arg? (or a quick link for how to look up what the latest release version is, and then how to specify it?)

They are now on a pretty tight schedule: every 1st, 4th, 7th and 10th, released on the next month. A script, anyway, might solve it straight away.

[tianon]

Indeed, for most of the images maintained under https://github.com/docker-library, we write an update.sh script which simply bumps the version numbers, then we have a Jenkins instance which is responsible for running that periodically, build-testing the result, then pushing an update commit directly to the relevant repository.

When we notice such commits (which I get directly to my inbox via GitHub's atom feed from our @docker-library-bot's activity feed), we then make the appropriate PR to https://github.com/docker-library/official-images. We even have a maintainer or two who automate that final PR. :+1:

[JJ]

I'm closing this now... If you want me to work on it and resubmit it, just reopen it. It's got a conflict, now, too...

[JJ]

I can resubmit the non-Dockerfile changes separately, for instance...