Enable HTTP/2 on preload/delegate nodes

[Marcin Rataj]

Problem

HTTP/2 is not supported on preload/delegate hostnames:

• node0.preload.ipfs.io, node1.preload.ipfs.io
• node0.delegate.ipfs.io,node1.delegate.ipfs.io

Test

$ npm install -g is-http2-cli

$ is-http2 ipfs.io
✓ HTTP/2 supported by ipfs.io
Supported protocols: h2 http/1.1

$ is-http2 node0.delegate.ipfs.io
× HTTP/2 not supported by node0.delegate.ipfs.io
Supported protocols: http/1.1

Motivation

Preload/delegate (ipfs/js-ipfs#2155) hosts receive multiple parallel requests from js-ipfs running in browser context. Browsers limit the number of concurrent requests/connections to ~6.

In HTTP/2 requests are multiplexed on a single connection, which improves performance and removes the amount of requests being in pending state.

[Michael Burns]

This is live.

mburns@rialto:~)$ sudo /usr/bin/is-http2 node0.delegate.ipfs.io
✓ HTTP/2 supported by node0.delegate.ipfs.io
Supported protocols: h2 http/1.1