ExtProc's latency information for monitoring #10912
Description
Gloo Edge Product
Enterprise
Gloo Edge Version
1.18.13
Is your feature request related to a problem? Please describe.
We have done a thorough research on the ExtProc upstream latency monitoring. Our findings are Envoy stats (https://www.envoyproxy.io/docs/envoy/latest/configuration/http/http_filters/ext_proc_filter) does not emit processing time for Ext-Proc (upstream), nor Envoy's access logging (https://www.envoyproxy.io/docs/envoy/latest/configuration/observability/access_log/usage) provides any external processing latency information.
Describe the solution you'd like
Enhance Envoy external processing filter's stats to produce rq_time histogram metric. Sample output would look like the following:
cluster.default-ext-proc-grpc-4444_gloo-system.upstream_rq_time: P0(nan,4) P25(nan,5.0964285714285715) P50(nan,7.026923076923077) P75(nan,8.003571428571428) P90(nan,8.087142857142856) P95(nan,11.524999999999999) P99(nan,12.61) P99.5(nan,12.805) P99.9(nan,12.960999999999999) P100(nan,13)
Describe alternatives you've considered
Customers currently use custom solutions to track individual ExtProc service latency. This isn't scalable because it demands unique latency tracking logic within each ExtProc service. If Envoy's external processing filter could produce request time latency information, it would significantly benefit any customers using the Dynamic Forward Proxy filter. This would transform it into a convenient, out-of-the-box solution.
Additional Context
No response