Fix nginx buffering the webcam stream into RAM on the fluidd interface - #38
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arlophoenix wants to merge 2 commits into
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Fix nginx buffering the webcam stream into RAM on the fluidd interface#38arlophoenix wants to merge 2 commits into
arlophoenix wants to merge 2 commits into
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…nsail The mainsail server block sets postpone_output 0, proxy_buffering off and proxy_ignore_headers X-Accel-Buffering on every /webcam*/ location; the fluidd block sets none of them. With buffering left on, nginx spools an MJPEG stream a client cannot drain fast enough into its proxy temp directory. That directory is the compiled default /var/tmp/nginx/proxy, and on CrealityOS /var/tmp is a symlink to /tmp, which is tmpfs -- so the spill lands in RAM. This only makes the file consistent with itself; the mainsail block is unchanged.
proxy_max_temp_file_size defaults to 1024 MB. On these boxes the proxy temp path resolves into a ~100 MB tmpfs on a ~200 MB machine, so the default is an invitation to exhaust RAM. Setting it to 0 makes nginx pass proxied responses through synchronously and never write a temp file, so a slow client throttles the upstream instead of consuming memory. This covers every proxied response, not just the webcam -- including large /server/files/... gcode reads, which are routinely ~100 MB. Deliberately not relocating proxy_temp_path to /usr/data: that would trade RAM exhaustion for continuous eMMC writes on every stream.
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The fluidd server block in
files/moonraker/nginx.confproxies/webcam*/withoutproxy_buffering off, while the mainsail block in the same file has it on all four locations. Because nginx's compiledproxy_temp_pathis/var/tmp/nginx/proxyand/var/tmpis a symlink to/tmp, which is tmpfs, a client that drains the MJPEG stream slower than the camera produces it makes nginx spool the difference into RAM. The defaultproxy_max_temp_file_sizeis 1024 MB against a ~100 MB tmpfs on a ~200 MB machine, so nothing bounds it.On a K1C 2025 this exhausted memory in about two minutes mid-print. Shmem went from a flat 11.8 MB baseline to 93.5 MB in ninety seconds and plateaued at the tmpfs cap; the kernel evicted the entire buffer cache, moonraker logged a 7.17 second blocked event loop, klipper lost communication with
nozzle_mcu, power-loss recovery auto-resumed the print, and the OOM killer took moonraker. That MCU's retransmit counter sat at exactly 9 for the preceding two hours and has been 0 since, so the link was fine — the host was starved. The OOM dump attributes 93,796 kB to shmem that no process mapped, which is unmapped tmpfs file data. The same signature recurred on a second date peaking at 91,400 kB.This is not confined to port 4408.
scripts/creality_web_interface.shinsertslisten 80;afterlisten 4408 default_server;when the user selects fluidd as the port-80 interface, so on those installs the unprotected block is what answers a barehttp://<printer>/webcam/.The first commit gives the four fluidd
/webcam*/locations the same five directives the mainsail block already carries — it only makes the file consistent with itself, and the mainsail block is untouched. The second setsproxy_max_temp_file_size 0in thehttpblock as a backstop, so nginx passes proxied responses through synchronously and never writes a temp file; a slow client then throttles the upstream instead of consuming RAM. The two are separable if you want only the first. Pointingproxy_temp_pathat/usr/datawould also stop the RAM growth, but trades it for continuous eMMC writes on every stream, so it is deliberately not the fix here.Verified on a K1C 2025 (mid-print) and a K1C OG (standby): staged
nginx -tbefore and after install, gracefulnginx -s reloadwith the master PID unchanged both times so klipper and moonraker were never interrupted, then fluidd 200 on 4408 (and on port 80 for the OG), moonraker API 200, a ~71 KB snapshot and 5.3 MB of stream in 5 s.Test plan
grep -c "proxy_buffering off" files/moonraker/nginx.confreturns 8; diff is 21 insertions and 0 deletions, so the mainsail block is provably unchangednginx -tpasses on the rendered config, before and after install/tmpusage andShmemstayed flat, swap untouched, zero files created under/tmp/nginx/proxyNot addressed
The same unbounded-buffering exposure applies to any large proxied response, notably
/server/files/...gcode downloads that routinely run ~100 MB; theproxy_max_temp_file_size 0backstop covers those generically rather than being webcam-specific. Separately, moonraker has no restart supervision on these boxes, so an OOM kill from any cause leaves the web UI down until reboot — out of scope here.