Hi,

I have configured NGINX as an HTTP Asset locator, where the assets might found through a series of recursive errors by sequentially a series of different webservers. The problem that "I think" I have ran into, is that NGINX's recursive_error_pages is limited to a depth 11 servers, thus 11 errors 404 or 500 errors- is this a fact? Interesting enough I get a 500 internal server error when I hit this 11th member in the chain.

I have tested various scenarios and I always seem to be blocked at the 11th cascading call with a 500 error - I move different servers around in fear that one of them (upstream servers) had a problem, but it was not specific to a server, regardless which asset I was going after http:<mynginx>/srv<n>/file<n> - once it hit 11 in depth.

Anyone has any ideas of this limitation - or is there something that could be done?

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nginx.conf
========

#user nobody;
worker_processes 5;

pid /var/run/nginx.origin.pid;


events {
worker_connections 10000;
}

http {
include /etc/nginx.origin/mime.types;
default_type application/octet-stream;

log_format main '-->$upstream_cache_status<-- | '
'$remote_addr - $remote_user [$time_local] "$request" '
'| Upstream_Address "$upstream_addr" '
'| upstream_response_time $upstream_response_time '
'| msec $msec request_time $request_time '
'| OriginServer $upstream_addr';

log_format cache '***$time_local '
'-->$upstream_cache_status<-- '
'Cache-Control: $upstream_http_cache_control '
'Expires: $upstream_http_expires '
'"$request" ($status) '
'"$http_user_agent" ';

access_log /var/log/nginx/origin.nas.access.log main;

sendfile on;
keepalive_timeout 65;
server_tokens off;

add_header Upstream-Host $upstream_addr;
add_header Cache-Status $upstream_cache_status;

client_body_buffer_size 512k;
proxy_connect_timeout 5;
proxy_read_timeout 60;
proxy_send_timeout 5;
proxy_buffer_size 16k;
proxy_buffers 4 64k;
proxy_busy_buffers_size 128k;
proxy_temp_file_write_size 128k;

upstream setA {
server 10.10.30.9:10666;
}

upstream setB {
server 10.10.31.79:10666;
}
upstream setC {
server 10.10.72.109:10666;
}
upstream setD {
server 10.10.72.110:10666;
}
upstream setE {
server 10.10.72.201:10666;
}
upstream setF {
server 10.10.72.127:10666;
}
upstream setG {
server 10.10.72.128:10666;
}
upstream setH {
server 10.10.72.137:10666;
}
upstream setI {
server 10.10.31.238:10666;
}
upstream setJ {
server 10.10.72.134:10666;
}
upstream setK {
server 10.10.72.139:10666;
}
upstream setL {
server 10.10.76.110:10666;
}
upstream setM {
server 10.10.72.141:10666;
}
upstream setN {
server 10.10.72.126:10666;
}
upstream setO {
server 10.10.76.103:10666;
}
upstream setY {
server 10.10.73.90:10666;
server 10.10.73.91:10666;
}
upstream setZ {
server 10.10.38.88:10666;
server 10.10.38.89:10666;
}

server {
listen haproxy-local:10777;
server_name localhost;

recursive_error_pages on;
proxy_cache nginx_cache;
proxy_cache_valid 200 304 12h;
expires 1d;

#SetAHandler
location /
{
access_log /var/log/nginx/origin.handler.a.proxy_access.log main;

# THIS IS IMPORTANT! Turn this on so the error_page handlers will follow a chain.
# This should ONLY be under "location /". If it's under http{} or server{}, the scope
# is too large and we may get an infinite loop.
# ****************************************************************************************
# THE STATEMENT ABOVE FAILS TO NOTE THAT:
# when included under 'location' the chain only allows up to 2 server after the first one
#
error_page 404 502 503 504 500 = @SetBHandler;
proxy_intercept_errors on;

#If there is only one server in "server_set_X",
# make sure it's not the same server this nginx is deployed on. Otherwise, you'll get a possible infinite loop.
#You'll see the error log complain about 'max descriptors'.
proxy_pass http://setA;
proxy_set_header Host $host;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
#This is different from how long it takes to READ it. For that, use proxy_read_timeout
proxy_connect_timeout 60s;
proxy_next_upstream error timeout http_500 http_502 http_503 http_504 http_404;


# break;
}

location @SetBHandler
{
access_log /var/log/nginx/origin.handler.b.proxy_access.log main;
proxy_intercept_errors on;

#If 404, check next server set. If last, it should go to error page.
error_page 404 502 503 504 500 = @SetCHandler;
proxy_pass http://setB;
proxy_set_header Host $host;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_connect_timeout 60s;
proxy_next_upstream error timeout http_500 http_502 http_503 http_504 http_404;

}

location @SetCHandler
{
access_log /var/log/nginx/origin.handler.c.proxy_access.log main;
proxy_intercept_errors on;

#If 404, check next server set. If last, it should go to error page.
error_page 404 502 503 504 500 = @SetDHandler;
proxy_pass http://setC;
proxy_set_header Host $host;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_connect_timeout 60s;
proxy_next_upstream error timeout http_500 http_502 http_503 http_504 http_404;

}

location @SetDHandler
{
access_log /var/log/nginx/origin.handler.c.proxy_access.log main;
proxy_intercept_errors on;

#If 404, check next server set. If last, it should go to error page.
error_page 404 502 503 504 500 = @SetEHandler;
proxy_pass http://setD;
proxy_set_header Host $host;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_connect_timeout 60s;
proxy_next_upstream error timeout http_500 http_502 http_503 http_504 http_404;


}

location @SetEHandler
{
access_log /var/log/nginx/origin.handler.c.proxy_access.log main;
proxy_intercept_errors on;

#If 404, check next server set. If last, it should go to error page.
error_page 404 502 503 504 500 = @SetFHandler;
proxy_pass http://setE;
proxy_set_header Host $host;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_connect_timeout 60s;
proxy_next_upstream error timeout http_500 http_502 http_503 http_504 http_404;


}

location @SetFHandler
{
access_log /var/log/nginx/origin.handler.c.proxy_access.log main;
proxy_intercept_errors on;

#If 404, check next server set. If last, it should go to error page.
error_page 404 502 503 504 500 = @SetGHandler;
proxy_pass http://setF;
proxy_set_header Host $host;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_connect_timeout 60s;
proxy_next_upstream error timeout http_500 http_502 http_503 http_504 http_404;


}

location @SetGHandler
{
access_log /var/log/nginx/origin.handler.c.proxy_access.log main;
proxy_intercept_errors on;

#If 404, check next server set. If last, it should go to error page.
error_page 404 502 503 504 500 = @SetHHandler;
proxy_pass http://setG;
proxy_set_header Host $host;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_connect_timeout 60s;
proxy_next_upstream error timeout http_500 http_502 http_503 http_504 http_404;

}

location @SetHHandler
{
access_log /var/log/nginx/origin.handler.c.proxy_access.log main;
proxy_intercept_errors on;

#If 404, check next server set. If last, it should go to error page.
error_page 404 502 503 504 500 = @SetIHandler;
proxy_pass http://setH;
proxy_set_header Host $host;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_connect_timeout 60s;
proxy_next_upstream error timeout http_500 http_502 http_503 http_504 http_404;

}

location @SetIHandler
{
access_log /var/log/nginx/origin.handler.c.proxy_access.log main;
proxy_intercept_errors on;

#If 404, check next server set. If last, it should go to error page.
error_page 404 502 503 504 500 = @SetJHandler;
proxy_pass http://setI;
proxy_set_header Host $host;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_connect_timeout 60s;
proxy_next_upstream error timeout http_500 http_502 http_503 http_504 http_404;

}

location @SetJHandler
{
access_log /var/log/nginx/origin.handler.c.proxy_access.log main;
proxy_intercept_errors on;

#If 404, check next server set. If last, it should go to error page.
error_page 404 502 503 504 500 = @SetKHandler;
proxy_pass http://setJ;
proxy_set_header Host $host;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_connect_timeout 60s;
proxy_next_upstream error timeout http_500 http_502 http_503 http_504 http_404;

}

location @SetKHandler
{
access_log /var/log/nginx/origin.handler.c.proxy_access.log main;
proxy_intercept_errors on;

#If 404, check next server set. If last, it should go to error page.
error_page 404 502 503 504 500 = @SetLHandler;
proxy_pass http://setK;
proxy_set_header Host $host;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_connect_timeout 60s;
proxy_next_upstream error timeout http_500 http_502 http_503 http_504 http_404;

}

location @SetLHandler
{
access_log /var/log/nginx/origin.handler.c.proxy_access.log main;
proxy_intercept_errors on;

#If 404, check next server set. If last, it should go to error page.
error_page 404 502 503 504 500 = @SetMHandler;
proxy_pass http://setL;
proxy_set_header Host $host;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_connect_timeout 60s;
proxy_next_upstream error timeout http_500 http_502 http_503 http_504 http_404;

}
location @SetMHandler
{
access_log /var/log/nginx/origin.handler.c.proxy_access.log main;
proxy_intercept_errors on;

#If 404, check next server set. If last, it should go to error page.
error_page 404 502 503 504 500 = @SetNHandler;
proxy_pass http://setM;
proxy_set_header Host $host;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_connect_timeout 60s;
proxy_next_upstream error timeout http_500 http_502 http_503 http_504 http_404;

}
location @SetNHandler
{
access_log /var/log/nginx/origin.handler.c.proxy_access.log main;
proxy_intercept_errors on;

#If 404, check next server set. If last, it should go to error page.
error_page 404 502 503 504 500 = @SetOHandler;
proxy_pass http://setN;
proxy_set_header Host $host;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_connect_timeout 60s;
proxy_next_upstream error timeout http_500 http_502 http_503 http_504 http_404;

}
location @SetOHandler
{
access_log /var/log/nginx/origin.handler.c.proxy_access.log main;
proxy_intercept_errors on;

#If 404, check next server set. If last, it should go to error page.
error_page 404 502 503 504 500 = @SetYHandler;
proxy_pass http://setO;
proxy_set_header Host $host;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_connect_timeout 60s;
proxy_next_upstream error timeout http_500 http_502 http_503 http_504 http_404;

}
location @SetYHandler
{
access_log /var/log/nginx/origin.handler.c.proxy_access.log main;
proxy_intercept_errors on;

#If 404, check next server set. If last, it should go to error page.
error_page 404 502 503 504 500 = @SetZHandler;
proxy_pass http://setY;
proxy_set_header Host $host;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_connect_timeout 60s;
proxy_next_upstream error timeout http_500 http_502 http_503 http_504 http_404;

}

location @SetZHandler
{
access_log /var/log/nginx/origin.handler.f.proxy_access.log main;
#If 404, check next server set. If last, it should go to error page.
#error_page 404 502 503 504 /404.html;
#error_page 404 /404.html;
proxy_pass http://setZ;
proxy_set_header Host $host;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_connect_timeout 60s;
proxy_next_upstream error timeout http_500 http_502 http_503 http_504 http_404;
#Last proxy, return whatever it gives
proxy_intercept_errors off;

}

# redirect server error pages to the static page /50x.html
#
error_page 500 502 503 504 /50x.html;
location = /50x.html {
root html;
}

location = /404.html {
root html;
}

location = /crossdomain.xml {
access_log /var/log/nginx/origin.handler.crossdomain.proxy_access.log main;
root html;
}
}

}