Sébastien,
Nginx should keep active connections open and wait for a request to
complete before closing.
A reload starts a new set of workers while old workers wait for old
connections to shut down.
The only exception I'm aware of is having worker_shutdown_timeout
configured: in this case a worker will wait till this timeout and
forcibly close a connection. Be default there is no timeout.
It would be curious to see error log of nginx at IP_1 (the reloaded one)
while the reload happens. It may explain the reason for connection resets.
Kind regards,
Igor.
On 25/03/2024 12:31, Sébastien Rebecchi wrote:
Hello
I have an issue with nginx closing prematurely connections when reload
is performed.
I have some nginx servers configured to proxy_pass requests to an
upstream group. This group itself is composed of several servers which
are nginx themselves, and is configured to use keepalive connections.
When I trigger a reload (-s reload) on an nginx of one of the servers
which is target of the upstream, I see in error logs of all servers in
front that connection was reset by the nginx which was reloaded.
Here configuration of upstream group (IPs are hidden replaced by IP_X):
--- BEGIN ---
upstream data_api {
random;
server IP_1:80 max_fails=3 fail_timeout=30s;
server IP_2:80 max_fails=3 fail_timeout=30s;
server IP_3:80 max_fails=3 fail_timeout=30s;
server IP_4:80 max_fails=3 fail_timeout=30s;
server IP_5:80 max_fails=3 fail_timeout=30s;
server IP_6:80 max_fails=3 fail_timeout=30s;
server IP_7:80 max_fails=3 fail_timeout=30s;
server IP_8:80 max_fails=3 fail_timeout=30s;
server IP_9:80 max_fails=3 fail_timeout=30s;
server IP_10:80 max_fails=3 fail_timeout=30s;
keepalive 20;
}
--- END ---
Here configuration of the location using this upstream:
--- BEGIN ---
location / {
proxy_pass http://data_api;
proxy_http_version 1.1;
proxy_set_header Connection "";
proxy_set_header Host $host;
proxy_set_header X-Real-IP $real_ip;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_connect_timeout 2s;
proxy_send_timeout 6s;
proxy_read_timeout 10s;
proxy_next_upstream error timeout http_502 http_504;
}
--- END ---
And here the kind of error messages I get when I reload nginx of "IP_1":
--- BEGIN ---
2024/03/25 11:24:25 [error] 3758170#0: *1795895162 recv() failed (104:
Connection reset by peer) while reading response header from upstream,
client: CLIENT_IP_HIDDEN, server: SERVER_HIDDEN, request: "POST
/REQUEST_LOCATION_HIDDEN HTTP/2.0", upstream:
"http://IP_1:80/REQUEST_LOCATION_HIDDEN
<http://IP_1:80/REQUEST_LOCATION_HIDDEN>", host: "HOST_HIDDEN",
referrer: "REFERRER_HIDDEN"
--- END ---
I thought -s reload was doing graceful shutdown of connections. Is it
due to the fact that nginx can not handle that when using keepalive
connections? Is it a bug?
I am using nginx 1.24.0 everywhere, no particular
Thank you for any help.
Sébastien
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