I am using FRiCKLE's ngx_cache_purge module to invalidate proxy caches. I ran into a problem of not being able to purge caches when accessing the invalidation url with a different HOST part of url than the one used to access the original content. For example, if I access the content like this:
curl -H 'Content-Type: application/json' -d '{ "token": "pts7v4nqf7stfq35qeb570v5n2" }' -X POST -D - http://api.example.com/news/article/cache-testing
The cache file is created with a propper key and it works, the subsequent requests are served right. When the content changes, in order to purge the cached data, the backend does the equivalent on all webservers:
curl -D - http://10.200.100.101:8080/invalidate_cached_url/POST/news/article/cache-testing
And this returns 404 since the cache file is somehow being generated with host
part of the url in mind, and in order to purge it, I have to call the invalidation url with the same host in line. This is a problem since I have a loadbalancer infront of the webstack.
To prove this, I saved the cache file generated with the above method and cleared the cache, then I visited the api endpoint directly with the IP address:
curl -H 'Content-Type: application/json' -d '{ "token": "pts7v4nqf7stfq35qeb570v5n2" }' -X POST -D - http://10.200.100.101:8080/news/article/cache-testing
Now when I try to purge the cache like above, it works. And true enough the cache files are different but on a binary level, but the keys are the same.
Is there a way around this?
Here's my config:
proxy_cache_path /tmp/nginx/example-api levels=1:2 keys_zone=example_api_zone:300m inactive=1h;
upstream origin_api {
server localhost:8888;
}
server {
listen 8080 default_server;
server_name api.example.com;
proxy_buffering on;
proxy_buffer_size 1k;
proxy_buffers 24 4k;
proxy_busy_buffers_size 8k;
proxy_max_temp_file_size 2048m;
proxy_temp_file_write_size 32k;
proxy_cache_key $request_method$uri;
access_log /var/log/nginx/example-api.access.log;
error_log /var/log/nginx/example-api.error.log;
error_page 500 502 /502.html;
location = /502.html {
internal;
root /opt/errors;
}
location / {
gzip on;
include example_proxy_params.conf;
proxy_cache_bypass $http_cache_control;
proxy_cache_methods POST GET;
proxy_pass http://origin_api;
}
location ~ ^/news/singlearticle/ {
gzip on;
proxy_hide_header Cache-Control;
add_header Cache-Control 'max-age=10s, no-cache ,public';
include example_proxy_params.conf;
proxy_cache_bypass $http_cache_control;
proxy_cache_methods POST GET;
proxy_pass http://origin_api;
}
location ~ ^/news/subcategory/ {
proxy_cache_key "$request_method$request_uri|$request_body";
include example_proxy_params.conf;
proxy_cache_bypass $http_cache_control;
proxy_cache_methods POST GET;
proxy_pass http://origin_api;
}
location ~ /invalidate_cached_url/(.*) {
allow 127.0.0.1;
allow 10.200.100.101;
allow 10.200.100.102;
deny all;
proxy_cache_purge example_api_zone $1;
}
}