Add support for include directive in watchers

[biozz]

There is a include directive in circus section of the config - https://circus.readthedocs.io/en/latest/for-ops/configuration/#circus-single-section

But there is no such thing in watcher section.

It would be nice to have it there, because there are a lot of cases when you define the same config for different watchers and only watcher id is changing.

For example - https://circus.readthedocs.io/en/latest/for-ops/papa/ has at lease these duplicated rows lines:

stdout_stream.class = FileStream
stdout_stream.filename = /var/logs/logger.log
stdout_stream.max_bytes = 10000000
stdout_stream.backup_count = 10
stderr_stream.class = FileStream
stderr_stream.filename = /var/logs/logger.log
stderr_stream.max_bytes = 1000000
stderr_stream.backup_count = 10

So if we have include directive for this we can do something like this:

; circus.ini
[circus]
loglevel = info

[watcher:logger]
cmd = /my_service/env/bin/python logger.py run
working_dir = /my_service
graceful_timeout = 10
singleton = true
stop_signal = INT
include = logs.ini

[watcher:web_app]
cmd = /my_service/env/bin/uwsgi --ini uwsgi-live.ini --socket fd://$(circus.sockets.web) --stats 127.0.0.1:809$(circus.wid)
working_dir = /my_service/web_app
graceful_timeout=10
stop_signal = QUIT
use_sockets = True
include = logs.ini

; logs.ini
stdout_stream.class = FileStream
stdout_stream.filename = /var/logs/$(circus.wid).log
stdout_stream.max_bytes = 10000000
stdout_stream.backup_count = 10
stderr_stream.class = FileStream
stderr_stream.filename = /var/logs/$(circus.wid).log
stderr_stream.max_bytes = 1000000
stderr_stream.backup_count = 10

[k4nar]

I like the idea, although I think that keeping everything in the same file would be a great plus. Maybe we could introduce a new section in the conf, and allow to include it?

[biozz]

If you use include syntax you are implying that it should work the same way in circus and other sections, making it consistent. But I agree you can be lost in your config files at times.

Having a new kind of section with extra configs, on the other hand, would work only for watcher. Because you usually don't have repeating stuff in socket or env. And I am also not sure how can we call that new section kind. Something like common or extra. Calling it include will make it inconsistent in my opinion.

And this looks a bit strange to me:

[watcher:app_1]
cmd = echo
extra = logs

[watcher:app_2]
cmd = echo
extra = logs

[extra:logs]
stdout_stream.class = FileStream

@k4nar, could you please give an example config how you see it done?

[k4nar]

I don't really have a better solution to offer :) . Let's implement the include instead, as it's probably the easiest & less confusing option.