Add (official) support of MS Windows OS

Currently (according to setup.py), nameko does not support MS Windows.

On the other hand (as @mattbennett mentioned in #624)

Anecdotally I gather that quite a few folks run it on Windows, but our CI currently tests on Linux only.

To me it seems (according to our own experience - colleague of mine develops on MS Windows), MS Windows support is already there, at least for the most significant features (worker run via CLI).

I can imagine multiple levels of MS Windows support (with growing strength):

1. MS Windows support rejected
2. MS Windows support intended, thus preventing not compatible solutions where possible
3. MS Windows support declared in setup.py (rather formal step)
4. MS Windows support proved by related test suite run on MS Windows

I would propose to jump to level 2 or 3 now and meantime add MS Windows related CI suite.

[davidszotten]

Hi,

As I recall, historically the main reason we didn’t support windows was that none of the core devs used windows so we couldn’t commit to supporting it. there was also no good free ci alternative for windows.

(in your list above, i would put ci before “declared” support)

in general i would be in favour of supporting windows, if someone has the time to get ci set up (is appveyor still the platform of choice there?)

i guess it might depend on how much work would be required to support it, but i would guess that’s manageable.

one more consideration is the dev experience, especially for new users, but given docker (for eg rabbit) i think that should also be fine nowadays

so for me the next steps would be something like:

1. a branch that starts running tests on windows, so we can see what (if anything) breaks
2. either make that check optional, or add commits to the branch and hold off merging until it passes (the former is probably my preference)
3. make passing tests on windows required
4. (if windows compat was hard, possibly wait a little to see how likely it is for new prs to only break on windows and how hard it is to fix; but if 3 was straightforward, just skip this)
5. declare windows support

[mattbennett]

However, there are a lot of bugs on the eventlet side which basically causes us to disable most of eventlet when running on windows (as far as I know eventlet also does not run CI on windows).

This is probably a killer. I think David’s list still applies, but we may never get past step 3.