How to use nginx as a proxy cache

The purpose of using cache is to reduce the pressure on the backend and improve website concurrency. In website design, in order to achieve better decentralization, we will try our best to concentrate the requests on the front end, where they can be processed.

Common cache types include client cache, proxy cache, server cache, etc.

Client cache [cache is stored locally, such as data is stored in the user's browser cache and read locally] Proxy cache [cache is stored on the proxy or middleware, such as data obtained from the server is placed on nginx, and nginx cache is directly read when accessed] Server cache [cache is stored on the server, often using redis and memchache, such as data in key-value format]

A brief description of the proxy cache:

Nginx proxy cache configuration:

proxy_cache_path /opt/www/cache levels=1:2 keys_zone=test_cache:10m max_size=10g inactive=60m use_temp_path=off;
 
server { 
	 listen 80;
	 server_name cache.test.com;
	 #rewrite ^/(.*)$ https://${server_name}$1 permanent; #Jump to Https
 
     if ($request_uri ~ ^/(test.html|login|register|password|\/reset)) {
            set $cookie_nocache 1;
     }
 
	 location / { 
		    proxy_cache test_cache; #The keys_zone value should be equal to proxy_cache_path proxy_pass http://127.0.0.1:8081;
            proxy_cache_valid 200 304 12h;
            proxy_cache_valid any 10m;
            proxy_cache_key $host$uri$is_args$args;
            proxy_no_cache $cookie_nocache $arg_nocache $arg_comment;
            proxy_no_cache $http_pragma $http_authorization;
    }
}

Parameter explanation:

• proxy_cache_path cache file path
• levels sets the cache file directory hierarchy; levels=1:2 means two levels of directory
• keys_zone sets the cache name and the size of the allocated space. 10m means 10 MB.
• max_size The maximum size of this directory. 10g means 10 GB. If it exceeds 10G, nginx will delete some cached data according to its own elimination and deletion rules, and overwrite the cached data with the longest cache time by default.
• inactive If no one accesses it within the specified time, it will be deleted. 60m means 60 minutes
• use_temp_path is used to store temporary files. It is recommended to set it to off

For more parameters, please refer to the nginx official website: Module ngx_http_proxy_module: http://nginx.org/en/docs/http/ngx_http_proxy_module.html#proxy_cache_path

• proxy_cache test_cache indicates that the proxy cache has been enabled. If you do not want to use the proxy cache, set this value to off.
• proxy_pass proxy address
• proxy_cache_valid 200 304 12h; The response with status code 200 or 304 expires in 12h.
• proxy_cache_valid any 10m; The cache time for status codes other than 200 and 304 is 10 minutes.
• proxy_cache_key $host$uri$is_args$args; Sets the default cache key. $is_args indicates whether the URL in the request has parameters. If it does, the value of $is_args is "?". If no parameters are given, this is an empty string. $args represents the parameters in the HTTP request.
• proxy_no_cache When the url matches test.html , login , register , password and reset , the page corresponding to this url will not be cached.

After the configuration is complete, check whether the syntax is correct nginx -tc /etc/nginx/nginx.conf, then reload the service nginx -s reload

Appendix: Smooth restart of nginx

[root@localhost nginx]# nginx -s reload

[root@localhost nginx]# ps -elf|grep nginx

1 S root 10175 1 0 80 0 - 27830 sigsus 09:52 ? 00:00:00 nginx: master process nginx

5 S www 11165 10175 0 80 0 - 28893 ep_pol 18:10 ? 00:00:00 nginx: worker process

5 S www 11166 10175 0 80 0 - 28893 ep_pol 18:10 ? 00:00:00 nginx: worker process

5 S www 11167 10175 0 80 0 - 27830 ep_pol 18:10 ? 00:00:00 nginx: cache manager process

After the restart is complete, there will be an additional cache manager, whose main function is similar to the LRU algorithm of memcached, deleting expired cache. However, if the cache has not expired and the server data has changed, the wrong data will still be accessed. This can be achieved through programming.

Summarize

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