2.4.0 has been released!
Numerous HTTP/2 options have been added to control the HTTP/2 SETTINGS and general behavior of HTTP/2 connections. The options for initial window sizes, maximum frame sizes or compression table sizes might be of interest for optimizing the performance of HTTP/2 connections.
Experimental support for Websocket over HTTP/2 was added. Note that browsers do not currently support it. The only browser with partial support is Google Chrome 67 (dev build) started with a specific flag. As a result it's disabled by default in Cowboy too.
All of Cowboy's RFC7540 tests and all of the h2spec test suite cases now pass. There are still parts that are not implemented (the priority mechanisms for example) and edge cases that are not covered, however, so the HTTP/2 support can still be improved.
A complete list of changes can be found in the migration guide: Migrating from Cowboy 2.3 to 2.4.
You can donate to this project via BountySource. These funds are used to pay for additional servers for testing. A new server was added this month and allows me to test with additional Linux distributions Alpine, CentOS and Debian. Thanks in advance!
As usual, feedback is appreciated, and issues or questions should be sent via Github tickets. Thanks!