services.nghttpx.backends.*.params.affinity

If "ip" is given, client IP based session affinity is enabled. If "none" is given, session affinity is disabled.

Session affinity is enabled (by nghttpx) per-backend pattern. If at least one backend has a non-"none" affinity, then session affinity is enabled for all backend servers sharing the same pattern.

It is advised to set affinity on all backends explicitly if session affinity is desired. The session affinity may break if one of the backend gets unreachable, or backend settings are reloaded or replaced by API.

Please see https://nghttp2.org/documentation/nghttpx.1.html#cmdoption-nghttpx-b for more detail.