NewClientFromConfig has no mechanism to set timeouts

[jacksontj]

NewClientFromConfig calls NewRoundTripperFromConfig which returns an http.RoundTripper. That interface has no mechanism to set dial options (like dial timeout, etc.). Under the hood the DialContext is set to one from go-conntrack -- which supports passing a dialer. I'd like a mechanism to pass these dial options in. The main reason being that as it stands today if the scrape target etc. is blocking the packets or slow the scrape hands for quite a while (holding FDs, etc.).

I see a couple options:

• we add some options to the HTTPClientConfig for this
• we add a new method NewClientFromConfigWithDialer which takes a dialer and does the "right thing"
• something else I haven't thought of yet

[brian-brazil]

You can set a context on the request, that's how the blackbox exporter does it for example.

[jacksontj]

This let's me set a timeout for the entire request. I'm looking to specifically set a dial timeout. As an example. I want to timeout if tcp doesn't open in 100ms, but I'm okay with waiting 1s for the entire request. The only way to get that behavior is to set a dial timeout.

…

On Fri, Sep 21, 2018, 2:40 AM Brian Brazil ***@***.***> wrote: You can set a context on the request, that's how the blackbox exporter does it for example. — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub <#144 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/ABi3nRAHfhLrhLqraL3VdkHNIEv-0zoYks5udLQIgaJpZM4WzSkz> .

[brian-brazil]

This code is for use by the Prometheus project, what's the use case for that within that context?

[jacksontj]

As described in the initial issue. I'd like to not wait for the entire timeout (5s let's say) if I can't connect quickly. This reduces the number of fds that are held open etc. for hosts that are in SD but aren't actually available for whatever reason. On Sep 21, 2018 7:41 AM, "Brian Brazil" <notifications@github.com> wrote: This code is for use by the Prometheus project, what's the use case for that within that context? — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub <#144 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/ABi3ncMJ1np4lGlk-yDiTw5l_rzFEXUvks5udPqugaJpZM4WzSkz> .

[brian-brazil]

It doesn't appear that Prometheus needs this, and there's already a way to do it, so closing.

[jacksontj]

To be clear, there is not a way to do what I was describing (set dial timeouts) -- but it seems that no one else is interested