A tutorial on caching cache features Nginx

1, one of the traditional cache (404) This approach is to nginx 404 errors to the back end, and then use Proxy_store to save the back-end of the page.

1, one of the traditional cache (404)

This approach is to nginx 404 errors to the back end, and then use Proxy_store to save the back-end page.

Configuration:

Location/{
root/home/html/; #主目录
Expires 1d; #网页的过期时间
Error_page 404 =200/fetch$request_uri; #404定向到/fetch Directory
}

location/fetch/{#404定向到这里
internal; #指明这个目录不能在外部直接访问到
Expires 1d; #网页的过期时间
alias/home/html/#虚拟目录文件系统地址要和locaion/Consistent, Proxy_store will save the file to this directory
Proxy_pass http://www.sudone.com/#后端upstream地址,/fetch is also an agent
Proxy_set_header accept-encoding '; #让后端不要返回压缩 (gzip or deflate) content, save the compressed content will cause a fuss.
Proxy_store on; #指定nginx将代理返回的文件保存
Proxy_temp_path/home/tmp #临时目录, this directory to and/home/html in the same hard drive partition
}

Use the time also have to note is nginx to have permissions to/home/tmp and/home/html under the permission to write files, under Linux Nginx will generally be configured to nobody users to run, so that these two directories will be Chown nobody, Set to nobody user-specific, of course, can also chmod 777, but all experienced system administrators will recommend not to use 777 casually.

2. Traditional cache bis (!-E)

Principle and 404 jump basically consistent, but more concise some:

Location/{
root/home/html/;
Proxy_store on;
Proxy_set_header accept-encoding ';
proxy_temp_path/home/tmp;
if (!-f $request _filename)
{
Proxy_pass http://www.sudone.com/;
}
}

You can see that this configuration than 404 saved a lot of code, it is used to determine the requested file!-f in the file system does not exist, does not exist on the proxy_pass to the back end, return is also used Proxy_store save.

Both traditional caches have essentially the same advantages and disadvantages:
Disadvantage 1: Dynamic links with parameters, such as read.php?id=1, are not supported, because Nginx only saves the file name, so this link is only saved under the file system as read.php, so that when the user accesses the read.php?id=2, it returns incorrect results. At the same time does not support http://www.sudone.com/this form of home and level two directory http://www.sudone.com/download/, because the nginx is very honest, will be such a request to write the link to the file system, And this link is obviously a directory, so save failed. These situations require written rewrite to be saved correctly.
Disadvantages 2:nginx There is no mechanism for cache expiration and cleanup internally, these cached files will be permanently stored on the machine, and if there are many things to cache, it will burst the entire hard disk space. To do this, you can use a shell script to clean up regularly, and you can compose dynamic programs such as PHP to do real-time updates.
Disadvantage 3: Only 200 status code can be cached, so the back-end return 301/302/404 and other status code will not be cached, if there is a large number of access to the pseudo static link is deleted, it will continue to penetrate the back end of the load is not small pressure.
Disadvantage 4:nginx will not automatically select memory or hard disk as storage media, all by configuration, of course, in the current operating system will have the operating system-level file caching mechanism, so there is no need to worry about large concurrent reading caused by IO performance problems.

The disadvantage of Nginx traditional caching is that it is different from caching software such as squid, so it can also be considered as its advantage. In production applications it is often used as a partner with squid, squid for the link is often unstoppable, and nginx can stop its access, such as: http://sudone.com/? and http://sudone.com/on squid will be treated as two links , so it will cause two penetration, and Nginx will only save once, whether the link becomes http://sudone.com/?1 or http://sudone.com/?123, can not through nginx cache, thus effectively protect the back-end host.

Nginx will be very honest to save the link form to the file system, so that for a link, you can easily check its cache state and content on the machine, it can easily and other file managers such as rsync, such as the use of, it is completely a file system structure.

Both of these traditional caches can be stored in Linux under the/DEV/SHM, I usually do so, so that you can use the system memory to do the cache, the use of memory, cleaning up the expiration of the content will be much faster. In addition to using/dev/shm/to point the TMP directory to the/DEV/SHM partition, if there are a large number of small files and directories, but also to modify the memory partition of the number of inode and maximum capacity:

Mount-o size=2500m-o nr_inodes=480000-o Noatime,nodiratime-o REMOUNT/DEV/SHM

The above command is used on a machine with 3G memory, because the/DEV/SHM default maximum memory is half of the system memory is 1500M, this command will turn it up to 2500M, while the number of SHM system inode may not be enough by default, but it is interesting that it can be adjusted arbitrarily, The adjustment here is 480000 conservative, but it's basically enough.

3. Caching basedon mem Cache D

Nginx has support for memcached , but the function is not particularly strong, performance is still very good.

location/mem/{
if ($uri ~ "^/mem/([0-9a-za-z_]*) $")
{
Set $memcached _key "$";
Memcached_pass 192.168.1.2:11211;
}
Expires 70;
}

This configuration will indicate the HTTP://SUDONE.COM/MEM/ABC to the memcached ABC key to fetch the data.

Nginx does not currently have any mechanism to write to the memcached, so writing data to memcached is done in a background dynamic language that can be directed to the back end to write data using 404.

4, based on Third-party Plug-ins Ncache

Ncache is a good project developed by the Sina Brothers, it uses Nginx and memcached to achieve a part of the function similar to squid cache, I do not use this plug-in experience, you can refer to:

http://code.google.com/p/ncache/

5, Nginx New development of Proxy_cache function

Starting from the nginx-0.7.44 version, nginx support similar squid more formal cache function, is still in the development phase, support is very limited, this cache is the link with MD5 encoded hash after saving, so it can support any link, but also support 404/301/ 302 such a non-200 state.

Configuration:

First configure a cache space:

Proxy_cache_path/path/to/cache levels=1:2 keys_zone=name:10m inactive=5m max_size=2m clean_time=1m;

Note that this configuration is outside the Server tab, levels specifies that the cache space has a two-layer hash directory, the first level is 1 letters, the second layer is 2 letters, the saved file name will be similar/path/to/cache/c/29/ B7f54b2df7773722d382f4809d65029c;keys_zone a name for this space, 10m refers to the space size of 10mb;inactive 5m refers to the cache default length of 5 minutes; max_ The 2m of size means that a single file is not cached when it is over 2m; clean_time specifies a minute to clean the cache.

Location/{
Proxy_pass http://www.sudone.com/;

Proxy_cache NAME; #使用NAME这个keys_zone

Proxy_cache_valid 302 1h; #200和302状态码保存1小时
Proxy_cache_valid 1d; #301状态码保存一天
Proxy_cache_valid any 1m; #其它的保存一分钟
}