How to listen (scrape endpoint) on both IPv4 and IPv6

[ijackson]

I am looking at the docs for metrics_exporter_prometheus::PrometheusBuilder:

AFAICT I can call with_http_listener only once, so I can't pass both an IPv4 and IPv6 socket address. I don't see a way to configure the listener socket in v6-mapped mode, either, which would let us use the same socket.

Also, if we wanted to listen on non-localhost, both for v4 and v6, we'd need a way to specify two actual addresses.

I think the answer is probably to provide with_http_listeners that takes an iterator of SocketAddr, or similar.

[tobz]

Your understanding of the current behavior is correct.

Similar to a comment I left on this sort of thing in #573, my position is that PrometheusBuilder is already far too overloaded, and I can't add an escape hatch for every situation. If listening on multiple addresses is something you need, then my suggestion would be to write the boilerplate to do so, and spawn your own HTTP server that simply uses PrometheusHandle to render the metrics.