net/http: make Transport ignore 408 timeout messages from server [1.12 backport]

[gopherbot]

@bradfitz requested issue #32310 to be considered for backport to the next 1.12 minor release.

@gopherbot, please backport.

[bradfitz]

This is an unusual backport rationale: popular HTTP servers on the Internet (at least, all of Google's) changed their behavior, and without this Go logs a warning to stderr, without a way to disable it.

I suspect people will get annoyed by that, so this is somewhat preemptive. I was annoyed when I started seeing it in my logs the other day. I don't know when Google's GFEs started sending 408s, but I suspect it was recently since I started seeing the log messages.

And if we do this, maybe Go 1.11 too (#32366).

/cc @ianlancetaylor @rsc @dmitshur @bcmills

[ianlancetaylor]

I'm fine with backporting this. It may or may not be critical, but there is no workaround.

[bradfitz]

I suppose one workaround is people can do log.SetOutput(filteringWriter{}), but that'll get tedious and gross pretty quickly.

[dmitshur]

I'm going to approve this unusual backport because the workaround is quite complicated and error prone (it requires implementing a filteringWriter and not making a mistake in its implementation, or forking net/http). It's not a very serious issue itself, but it can spam log output and hide other important information from logs, which makes it more serious. I'm also taking into account that Brad and Ian are okay with it.

[gopherbot]

Change https://golang.org/cl/181239 mentions this issue: [release-branch.go1.12] net/http: prevent Transport from spamming stderr on server 408 reply

[gopherbot]

Closed by merging 918368e to release-branch.go1.12.

[andybalholm]

popular HTTP servers on the Internet (at least, all of Google's) changed their behavior, and without this Go logs a warning to stderr, without a way to disable it.

I've been seeing this behavior for months or years. (I don't remember what servers, though.) I never thought of filing an issue for it, but I'm glad to see it fixed.