prometheus/client: implement protobuf exposition format
Implement the Protobuf exposition format. Protobuf file has been copied
from https://github.com/prometheus/client_model. Please pardon the code
quality - I'm relatively new to Rust and just wanted to get something
working. Is this something you would be interested in? I could clean up
the code and add the missing pid
label.
Also, I see that single-process formatting is pretty much broken and
ignored? The only used value class has true
hardcoded in the
multiprocessing field so the C/Rust extension is always used AFAICT.
Thus, do I also need on adding protobuf support to the single-process
mode?
I would like to work on native histograms after this is merged. Let me know your comments/suggestions! Thank you.
Signed-off-by: Giedrius Statkevičius giedrius.statkevicius@vinted.com