specifying ip-address and portnumber

[devosalain]

specifying ip-address and portnumber

[dmagliola]

Hello,
Could you show us some sample code, or provide a bit more context of what you are doing?

[devosalain]

My idea was to write a python client exporter for prometheus which spawns a webservice where prometheus can scrape the data of the gauges i write in this python program. Something like most existing exporters.
But for this i need to be able to specify the IP-address and port address.

Maybe another example to clarify. There exist a dovecot exporter for prometheus but you can specify the parameters.
"--web.listen-address="127.0.0.1:9166". So explicitly you can tell prometheus then to scrape on that IP-address and that specific port.
This is import in the case a port is already used by another instance which i think is in my case.

Or compare to python-code , because my knowledge of the ruby API is limited.
-> from prometheus_client import start_http_server
if name == 'main':
start_http_server(8000)
Works, but it is binding to all interfaces which is a serious security risk.

Maybe I need something like
prometheus = Prometheus::Client.registry(host:"127.0.0.1",port:"8000")

I looked at your code but was unable to find places where you pass IP-address or portnumber information which is essential for my use case.
Luckely the python api knows : "start_http_server(addr="127.0.0.1",port=38000)", but the ruby equivalent would be nice to have.

[dmagliola]

Our exporter middleware will allow you to filter by port, once we release the new version (which should be soon), so that's half the use case you are looking for. To also filter by IP you'd have to make your own exporter, you can start by copying the one in our master branch, and then adding the IP filtering.

That said, the error you describe seems to be that the same metric is being registered twice. This sounds like you are adding the Collector middleware twice?

[devosalain]

Currently I have 80 tcp listeners running for different reasons, so probably that port was already occupied.
One final question. Could you guide me to which ruby file in this repo, or which function within it, where i can, after cloning this repo, hardcode an IP-address & Port. Probably this is the deepest function, where not all parameters are given or the defaults are taken.

[dmagliola]

You don't need to clone the repo. The way our middleware works, you can just copy the contents of it into a file in your app, and add that middleware to Rack, you don't need to modify the gem, just point to your copy of the middleware instead.

This is the file you are looking for:
https://github.com/prometheus/client_ruby/blob/master/lib/prometheus/middleware/exporter.rb

That said, I still think the error you are receiving is not a "two things tried to open the same port". That error is "the same metric got registered twice".

[Sinjo]

Closing this as it's stale, and I think wasn't for something our gem would handle in the first place.

Luckely the python api knows : "start_http_server(addr="127.0.0.1",port=38000)", but the ruby equivalent would be nice to have.

We don't start any HTTP servers directly in the gem, and by extension don't bind to any network interfaces.