Add native HTTP/2 support

[hekike]

Please provide feedback in the comment section about this approach.

Issues

Related:

• Http2 support #853

Add HTTP/2 support to restify

Changes

• Adds HTTP/2 support to server
• Uses patch method to decorate Request and Response objects
• Example for HTTP/2 server with restify

TODO

• New Node.js release (8.5.0) that contains the http2: Expose Http2ServerRequest/Response nodejs/node#14690 change (exposes Http2ServerRequest and Http2ServerRespone objects)
• Node Node.js release with removed Http2ServerRequest path getter (> 8.5.0) see nodejs/node@c981483
• Stable, non experimental http2 module in Node.js (8.8.0, see: https://github.com/nodejs/node/blob/master/doc/changelogs/CHANGELOG_V8.md#2017-10-24-version-880-current-mylesborins)
• Tests for HTTP/2 (probably we should run all of the tests with both http2 and spdy options as well) (I think it's not needed, as the interface is the same and it's already tested in the Node core)

How to run

At the moment you need to build Node.js with the latest master and using the --expose-http2 flag to run this branch.

[retrohacker]

[yunong]

🎉 I've assigned a few reviewers to look at this, but this is amazing work so far.

[hekike]

@DonutEspresso @yunong @jclulow @retrohacker Node.js v8.8.0 is out which means we have everything that's needed to ship this feature, see changelog:

• no more conflict with the path getter
• http2 is now exposed by default without the need for a flag
• However http2 stability is still experimental in the Node core

I rebased this PR with the master and added a simple test case.
Do you want to wait more or can we ship it?

[yunong]

Looks great. What do you think about adding some documentation to the home page about how we support HTTP/2, but that it's still experimental? I think this would give us tremendous PR!

[yunong]

What happens if we're on a version of Node that doesn't support http2, does the current code handle this path?

[hekike]

@yunong I added an assert to the server.js http2 option.

The http2 related tests will be skipped with older versions:

HTTP2 module is not available
Node.js version >= v8.8.8 required, current: 6.9.4

OK: 0 assertions (4ms)

[hekike]

@yunong regarding docs and landing I can create some hands-on guide for restify's http2 support, some ideas:

• HTTP/2 Server Push: like I did here https://blog.risingstack.com/node-js-http-2-push/ (maybe a new static middleware with push capabilities)
• HTTP/1 fallback demonstration (we could even add helper functions for protocol detection)
• other?

[yunong]

@hekike That blog post is great, maybe we can link to some articles instead of having to maintain HTTP/2 specific documentation.

I was more thinking about just adding docs to say that we support HTTP/2 now, with some pointers to code snippets or examples, which you already have added.

[hekike]

@yunong I agree. What do you think, should we link the articles it in this PR?
I believe we could focus on the marketing after the feature is landed.

[yunong]

Yeah we should land and then follow up with some docs :)

[hekike]

Breaks because of: #1545