Has there been any thought about HTTP/3 and QUIC in the context of CVMFS?
While the reduced number of roundtrips for the handshake process may not be applicable for CVMFS using TCP without TLS, nevertheless there could be potentially significant performance improvements especially for lossy networks, long RTT, as well as improved congestion control algorithms. I’m not sure if head of line blocking affects CVMFS, but HTTP/3 should bring benefits for multiple simultaneous background downloads (bundling?). As always, the actual performance impact may depend on the environment and application and would need to be tested.
About 25% of the web uses HTTP/3 and it has been supported in libcurl for ~ 4 years. However it seems httpd and squid may be late adopters, with codebases from a different era that could make it difficult to add support for new protocols.