Tags `alpine` and `*-alpine` should refer to latest alpine release 3.7, not 3.4

[berndverst]

I am requesting that the alpine related tags without explicit version always refer to the latest stable alpine release. Currently this should be 3.7.

In https://github.com/docker-library/python/blob/master/generate-stackbrew-library.sh#L17 this already seems to be done. But it's unclear to me why Python 3.6 is explicitly being mapped to Alpine 3.4:
https://github.com/docker-library/python/blob/master/generate-stackbrew-library.sh#L22

defaultAlpineVersion='3.7'
declare -A alpineVersions=(
	[2.7]='3.4'
	[3.4]='3.4'
	[3.5]='3.4'
	[3.6]='3.4'

Desired: 3-alpine and alpine (and any other -alpine) tags should used latest stable python and alpine releases. Currently that is Python 3.6.4 and Alpine 3.7.

Current: 3-alpine and alpine tags use Alpine 3.4, several versions behind.

[berndverst]

Thoughts on this @yosifkit @JayH5 @tianon ?

[myoung34]

This would solve some issues I'm having with versions in the 3.4 container

[michael-k]

I am requesting that the alpine related tags without explicit version always refer to the latest stable alpine release.

This should be changed for all other tags, too. Eg. 3.6 should be an alias for 3.6.5-stretch and not 3.6.5-jessie.

But it's unclear to me why Python 3.6 is explicitly being mapped to Alpine 3.4

When 3.6-alpine was initially published on the docker hub, there were no images with tags that pinned the alpine version, ie. there was no 3.6-alpine3.x. When the tags were introduced, 3.6-alpine stayed pinned to Alpine 3.4 to guarantee stability for existing users.
See docker-library/golang#131 and the linked issues for examples where an update of alpine led to issues.

ruby:2.4-alpine is also an alias for ruby:2.4-alpine3.4 and golang:1.9-alpine is an alias for golang:1.9-alpine3.6 (both instead of 3.7).

That said, I think that at some point most users aiming for stability should have discovered the new tags and switched to one of them. And them 3.6-alpine should become a rolling tag (like debian:stable or ubuntu:rolling). Ideally this should be done hub wide and not on a per image basis (for consistency), but then there are official images like node that haven't made the switch to the new tagging schema.

And last but not least, I think that anyone aiming for stability should build their own python image. I consider official images as a source for best practices, not a source for stability, but maybe the majority of docker users thinks otherwise.

[bmw]

What's the plan for the *-alpine images when support ends for Alpine 3.4 in a couple weeks?