migrate the main rustdoc handlers to axum, drop iron

[syphar]

So, I couldn't make out a sensible intermediate step due to the overlapping routes between the rustdoc-redirector and -html-handler.

So this is all the rest of the handlers, and is dropping iron.

Some things to keep in mind:

• I'm dropping the LegacySharedResourceHandler, replaced with a piece in rustdoc_redirector_handler which serves assets only from the root. From the answers in Docs built during 2018-{10-12} link to the wrong url for static resources #1181 I would say we close that one then.
• I'm dropping my fix for double slashes ( fixes #1409: internal server error with two slashes at the end of the URL #1410 ), axum doesn't error here but just serves a normal 404 in these cases, which IMO is more correct. Of course I can re-add that functionality if needed.
• The .ico handling is migrated to a simple redirect to our global favicon, which is what I think was the intention in the original ico_handler (f3848a3 is the original commit)
• making the RenderingsTimeRecorder available in spawn_blocking when I call storage methods was difficult, so I disable measuring these steps for now, and will re-activate this when I migrate the storage to be async (which would be probably the next good step).

fixes

• some audit warnings: (RUSTSEC-2020-0016: net2 crate has been deprecated; use socket2 instead #760, RUSTSEC-2020-0056: stdweb is unmaintained #1122, RUSTSEC-2021-0078: Lenient hyper header parsing of Content-Length could allow request smuggling #1460, RUSTSEC-2021-0079: Integer overflow in hyper's parsing of the Transfer-Encoding header leads to data loss #1459, RUSTSEC-2021-0144: traitobject is Unmaintained #1826, RUSTSEC-2019-0039: typemap is Unmaintained #1827)
• Gracefully shutdown on signals #1150
• perhaps the need for a higher ulimit ( see improved warning for ulimit -n 4096 needed #1758 ), needs testing.

[syphar]

r? @Nemo157 @jyn514 @jsha

sorry for the mass-ping, but since all of you also touched this endpoint a help with reviewing would be awesome.

Also, even though there is some test coverage, some short manual tests with your local environments would be really helpful.

[jyn514]

this is awesome ❤️ lots of small comments, but no blockers

[jyn514]

Just noting the changes in behavior before the conversations get resolved:

• double slashes are now a 404 instead of a redirect (e.g. docs.rs//tokio)
• a couple handlers that special cased JS over other files have been removed
• we are going to lose timings from some of the database routes until we switch the codebase to async

I think it is somewhat likely this will introduce a regression by accident, but we can fix it after the fact, I expect it will be something small like the // routes actually being used.

Thank you for your work on this ❤️❤️❤️

[syphar]

Small correction : the double slash correction previously only handled double slashes at the end

[syphar]

This was merged into master as:

• 1177749
• a976543

I'm still doing the merge for documentation.