bleggett commented 1 week ago

Description

Adds support for wrapping Envoy listener transport sockets with the tcp_stats transport socket.

This allows Envoys stats endpoint to capture and report Linux-level TCP stats for a given listener, which can help with debugging:

ex:

listener.0.0.0.0_8082.tcp_stats.cx_rx_bytes_received: 234
listener.0.0.0.0_8082.tcp_stats.cx_rx_data_segments: 3
listener.0.0.0.0_8082.tcp_stats.cx_rx_segments: 15
listener.0.0.0.0_8082.tcp_stats.cx_tx_bytes_sent: 291
listener.0.0.0.0_8082.tcp_stats.cx_tx_data_segments: 3
listener.0.0.0.0_8082.tcp_stats.cx_tx_retransmitted_segments: 0
listener.0.0.0.0_8082.tcp_stats.cx_tx_segments: 6
listener.0.0.0.0_8082.tcp_stats.cx_tx_unacked_segments: 0
listener.0.0.0.0_8082.tcp_stats.cx_tx_unsent_bytes: 0
listener.0.0.0.0_8082.tcp_stats.cx_rtt_us: B0.5(0,0) B1(0,0) B5(0,0) B10(0,0) B25(0,3) B50(0,3) B100(0,3) B250(0,3) B500(0,3) B1000(0,3) B2500(0,3) B5000(0,3) B10000(0,3) B30000(0,3) B60000(0,3) B300000(0,3) B600000(0,3) B1.8e+06(0,3) B3.6e+06(0,3)
listener.0.0.0.0_8082.tcp_stats.cx_rtt_variance_us: B0.5(0,0) B1(0,0) B5(0,0) B10(0,3) B25(0,3) B50(0,3) B100(0,3) B250(0,3) B500(0,3) B1000(0,3) B2500(0,3) B5000(0,3) B10000(0,3) B30000(0,3) B60000(0,3) B300000(0,3) B600000(0,3) B1.8e+06(0,3) B3.6e+06(0,3)
listener.0.0.0.0_8082.tcp_stats.cx_tx_percent_retransmitted_segments: B0.5(0,3) B1(0,3) B5(0,3) B10(0,3) B25(0,3) B50(0,3) B100(0,3) B250(0,3) B500(0,3) B1000(0,3) B2500(0,3) B5000(0,3) B10000(0,3) B30000(0,3) B60000(0,3) B300000(0,3) B600000(0,3) B1.8e+06(0,3) B3.6e+06(0,3)

This is roughly analogous to the proxy_protocol transport socket wrapping we already support for clusters.

Note also that we should probably do this for clusters as well as listeners, but for now this is just adding listener support via the ListenerOptions API.

API changes

adds listenerTcpStats: true|false to the ListenerOptions API.

Checklist:

[x] I have performed a self-review of my own code
[x] I have commented my code, particularly in hard-to-understand areas
[x] I have made corresponding changes to the documentation
[x] I have added tests that prove my fix is effective or that my feature works BOT NOTES: resolves https://github.com/solo-io/solo-projects/issues/7176