Add source_ip_address support to http probes

[bobrik]

This is a logical continuation of #262.

It's the same as #765 but without changing prometheus/common as @roidelapluie suggested.

Signed-off-by: Ivan Babrou [email protected]

[bobrik]

@roidelapluie, this approach doesn't seem to work very well, given that there may be multiple layers of transport.

[roidelapluie]

@roidelapluie, this approach doesn't seem to work very well, given that there may be multiple layers of transport.

Can you be more explicit?

[bobrik]

Look at the failed test:

panic: interface conversion: http.RoundTripper is *config.basicAuthRoundTripper, not *http.Transport

I don't see a good way to update DialContext in http.RoundTripper that is wrapped by config.basicAuthRoundTripper.

[roidelapluie]

Hello @bobrik . Now the HTTP client supports passing special dialcontext funcs so we could implement all this in the blackbox exporter: prometheus/common#291