nginx always fetches from server - php

Question

I am trying to setup nginx as a caching reverse proxy, however it would appear that every request is been sent to the backend server, and nothing is been cached. i.e. the server logs on the backend show all the same file accesses.
Most of the files are either php with arguments passed on the url or images, all of which are been fetched all the time from the backend and never cached. Everything on this site can be cached.
My conf.d/default.conf
upstream xxxx {
server xxxx.com;
}
#
# The default server
#
server {
listen 80 default_server;
server_name _;
access_log /var/log/nginx/log/access.log main;
error_log /var/log/nginx/log/error.log;
root /usr/share/nginx/html;
index index.html index.htm;
location / {
## send request back to xxxx ##
proxy_pass http://xxxx;
proxy_next_upstream error timeout invalid_header http_500 http_502 http_503 http_504;
# expires 24h;
# add_header Cache-Control public;
proxy_ignore_headers Cache-Control Expires;
proxy_redirect off;
proxy_buffering off;
proxy_cache one;
proxy_cache_key backend$request_uri;
proxy_cache_valid 200 301 302 1440m;
proxy_cache_valid 404 1m;
proxy_cache_valid any 1440m;
proxy_cache_use_stale error timeout invalid_header updating;
proxy_set_header Host $host;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
}
}
and my nginx.conf file
user nginx;
worker_processes 8;
worker_rlimit_nofile 8192;
error_log /var/log/nginx/error.log;
#error_log /var/log/nginx/error.log notice;
#error_log /var/log/nginx/error.log info;
pid /var/run/nginx.pid;
events {
worker_connections 2048;
}
http {
include /etc/nginx/mime.types;
default_type application/octet-stream;
log_format main '$remote_addr - $remote_user [$time_local] "$request" '
'$status $body_bytes_sent "$http_referer" '
'"$http_user_agent" "$http_x_forwarded_for"';
access_log /var/log/nginx/access.log main;
server_names_hash_bucket_size 64;
sendfile on;
tcp_nopush on;
tcp_nodelay off;
#keepalive_timeout 0;
keepalive_timeout 65;
gzip on;
gzip_comp_level 9;
gzip_proxied any;
proxy_buffering on;
proxy_cache_path /usr/local/nginx/proxy levels=1:2 keys_zone=one:1024m inactive=7d max_size=700g;
proxy_temp_path /tmp/nginx/proxy;
proxy_buffer_size 4k;
proxy_buffers 100 8k;
proxy_connect_timeout 60;
proxy_send_timeout 60;
proxy_read_timeout 60;
include /etc/nginx/conf.d/*.conf;
}
Can anybody tell me what I've got wrong??

Answer 1

I ran into this problem as well, and I found
proxy_buffering off;
Will cause nginx to bypass cache and not save the file to disk.
Remove that line and then it works.

Answer 2

Your upstream server responses must be settings Cookies, please see
https://stackoverflow.com/a/10995522/482926