Try using alpine-based docker image (musl locale issues)

[jantman]

The Docker image for this is based on the non-alpine (debian) variant of the official Python image, which is 535 MB as opposed to 89 MB for alpine.

[jantman]

Tried work on this in noci-issues/125 branch, as of 152f1a6

Doesn't work. Alpine Linux is based on the musl C library, which doesn't have locale support. As a result, our many calls to locale.currency() fail with:

Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "/usr/local/lib/python3.6/locale.py", line 262, in currency
    raise ValueError("Currency formatting is not possible using "
ValueError: Currency formatting is not possible using the 'C' locale.

This issue needs to either wait for a usable musl locale support, or some non-Alpine (non-musl) tiny base image.

[jantman]

Ok, I've found a solution to this problem. The babel package is specifically designed to aid i18n and l10n in Python web applications, and has a format_currency function that doesn't rely on locale support, and works correctly in the Alpine-based Docker images. The function takes three arguments; the value to format, the currency specifier (i.e. 'USD') and the locale (i.e. 'en_US'). This does mean that we should probably make the currency specifier a configuration value, and should probably make the locale a configuration value as well, that we attempt to get from the environment/system if possible (or at least allow it to be overridden via env vars).

The locale issues with the Alpine image brought up some issues around Javascript, but we'll handle those in #140.

[jantman]

When I try this, bump to the 3.6.3-alpine3.6 image, or a newer one if available. Also, the locale test needs to be removed.

[jantman]

I don't know if this was happening before or not, but now I can't get phantomJS to run in the Alpine image. It seems like I'm hitting ariya/phantomjs#14186 where PhantomJS just doesn't work on Alpine/musl, and there doesn't seem to be a clear workaround at this time (though it seems like it did with earlier phantom and/or musl versions?)

[jantman]

Ok, I managed to find https://github.com/fgrehm/docker-phantomjs2 which provides a working phantomjs on Alpine in Docker, albeit phantomjs 2.0.0 instead of 2.1.1

[jantman]

Ok, using the last commit I have acceptance tests passing against an Alpine-based Docker container, and I have phantomjs 2.0.0 running in the container itself.