How to clear the cache of nginx?

Question

I use nginx to as the front server, I have modified the CSS files, but nginx is still serving the old ones.

I have tried to restart nginx, to no success and I have Googled, but not found a valid way to clear it.

Some articles say we can just delete the cache directory: var/cache/nginx, but there is no such directory on my server.

What should I do now?

Answer 1

For those who other solutions are not working, check if you're using a DNS service like CloudFlare. In that case activate the "Development Mode" or use the "Purge Cache" tool.

Answer 2

You can delete cache directory of nginx or You can search specific file:

grep -lr 'http://mydomain.pl/css/myedited.css' /var/nginx/cache/*

And delete only one file to nginx refresh them.

Answer 3

I had the exact same problem - I was running my nginx in Virtualbox. I did not have caching turned on. But looks like sendfile was set to on in nginx.conf and that was causing the problem. @kolbyjack mentioned it above in the comments.

When I turned off sendfile - it worked fine.

This is because:

Sendfile is used to ‘copy data between one file descriptor and another‘ and apparently has some real trouble when run in a virtual machine environment, or at least when run through Virtualbox. Turning this config off in nginx causes the static file to be served via a different method and your changes will be reflected immediately and without question

Answer 4

You can also bypass/re-cache on a file by file basis using

proxy_cache_bypass $http_secret_header;

and as a bonus you can return this header to see if you got it from the cache (will return 'HIT') or from the content server (will return 'BYPASS').

add_header X-Cache-Status $upstream_cache_status;

to expire/refresh the cached file, use curl or any rest client to make a request to the cached page.

curl http://abcdomain.com/mypage.html -s -I -H "secret-header:true"

this will return a fresh copy of the item and it will also replace what's in cache.

Answer 5

find /etc/nginx/cache_folder -type d -exec rm -rvf {} \;
mkdir /etc/nginx/cache_folder
service nginx restart

Be careful to properly specify the correct path.

Answer 6

We have a very large nginx cache (gigabytes) that we occasionally need to wipe. I've worked out a script that instantly clears the cache (as far as Nginx is concerned) and then removes the cache directory without starving the main application for disk I/O.

In summary:

1. Move the cache folder to a new location (on the same filesystem!) (this doesn't disrupt any open file descriptors)
2. Recreate the original cache folder, empty
3. Reload Nginx (graceful reload, where nginx lets old workers finish in-progress requests)
4. Remove old cached data

Here's the script, tailored to Ubuntu 16.04 LTS, with the cache located at /mnt/nginx-cache:

#!/bin/bash
set -e

TMPCACHE=`mktemp --directory --tmpdir=/mnt nginx-cache-XXXXXXXXXX`
TMPTEMP=`mktemp --directory --tmpdir=/mnt nginx-temp-XXXXXXXXXX`

# Move the old cache folders out of the way
mv /mnt/nginx-cache $TMPCACHE
mkdir -p /mnt/nginx-cache
chmod -R 775 /mnt/nginx-cache
chown www-data:www-data /mnt/nginx-cache

mv /mnt/nginx-temp $TMPTEMP
mkdir -p /mnt/nginx-temp
chmod -R 775 /mnt/nginx-temp
chown www-data:www-data /mnt/nginx-temp

# Tell Nginx about the new folders.
service nginx reload

# Create an empty folder.
rm -rf /mnt/empty
mkdir -p /mnt/empty

# Remove the old cache and old temp folders w/o thrashing the disk...
# See http://serverfault.com/questions/546177/how-to-keep-subtree-removal-rm-rf-from-starving-other-processes-for-disk-i
# Note: the `ionice` and `nice` may not actually do much, but why not?
ionice -c 3 nice -19 rsync -a --delete /mnt/empty/ $TMPCACHE
ionice -c 3 nice -19 rsync -a --delete /mnt/empty/ $TMPTEMP
rm -rf $TMPCACHE
rm -rf $TMPTEMP

rm -rf /mnt/empty

And in case it's helpful, here's the Nginx config we use:

upstream myapp {
    server localhost:1337 fail_timeout=0;
}

proxy_cache_path /mnt/nginx-cache/app levels=2:2:2 keys_zone=app_cache:100m inactive=1y max_size=10g;
proxy_temp_path  /mnt/nginx-temp/app;

server {
    listen   4316 default;
    server_name  myapp.com;

    location / {
        proxy_pass http://appserv;
        proxy_cache app_cache;
        proxy_cache_valid 200 1y;
        proxy_cache_valid 404 1m;
    }
}