php-fpm parsing misses critical REQUEST_URI parameter

[thoro]

@grcevski thinks it might be not yet using the improved buffer sizes added by @mmat11

Beyla Debug output produces a trace without url:

2025-10-23 19:26:00.10237260 (576.04µs[576.04µs]) HTTP 200 GET  [10.253.41.1 as 10.253.41.1:57520]->[10.253.41.196 as staging-cf-backend/mx-platon/backend-www.mx-platon:9000] contentLen:178B responseLen:0B svc=[mx-platon/staging-cf-backend/mx-platon/backend-www/php-fpm php] traceparent=[00-3214989ea231eddb26bb24ad195bc8b0-aeddc433f90c7e10[0000000000000000]-00]

Source tcpdump looks like this:

19:02:51.005619 IP 10.253.42.1.56204 > mx-platon-backend-www-59cf49959d-xqbvj.9000: Flags [P.], seq 17:171, ack 1, win 43, options [nop,nop,TS val 2618248703 ecr 1205074673], length 154
E.....@.@...
.*.
.*...#(.......?...+kd.....
..M.G.............HTTP_X_INSTANA_L0..SCRIPT_FILENAME/fpmstatus.php.	QUERY_STRINGfull&json..SCRIPT_NAME/fpmstatus.php..REQUEST_METHODGET..REQUEST_URI/fpmstatus.php
19:02:51.005622 IP mx-platon-backend-www-59cf49959d-xqbvj.9000 > 10.253.42.1.56204: Flags [.], ack 171, win 43, options [nop,nop,TS val 1205074673 ecr 2618248703], length 0
E..4..@.@..H
.*.
.*.#(.....?...=...+j......
G.....M.
19:02:51.005634 IP 10.253.42.1.56204 > mx-platon-backend-www-59cf49959d-xqbvj.9000: Flags [P.], seq 171:220, ack 1, win 43, options [nop,nop,TS val 2618248703 ecr 1205074673], length 49
E..e..@.@..a
.*.
.*...#(...=...?...+j......
..M.G........)..GET /fpmstatus.php?full&json HTTP/1.0

We tried to set:

OTEL_EBPF_BPF_BUFFER_SIZE_HTTP: 1024
BEYLA_BPF_BUFFER_SIZE: 1024

But this didn't help!

[grcevski]

I think we need to try using the large buffers for PHP FPM (fast CGI) too, I checked the request buffers we get from eBPF and they are cut-off.