Nginx + Lua + GraphicsMagick 实现切图服务

转载:http://houxiyang.com/archives/112/

面临的问题

网站需求变更，需要更多不同尺寸的缩略图

有些图片的缩略图很少使用到，但还是存在了硬盘上，造成空间浪费

解决方法

Nginx搭配Lua模块，如果访问的图片不存在，则调用GraphicsMagick的命令行实时生成指定尺寸的图片。

-集成了Lua模块的Nginx项目OpenResty

-GraphicsMagick的安装和使用

-具体使用方法

原始图片地址：

/images/f47aa98b47b4b7bd.jpg

自定义图片尺寸：

/images/f47aa98b47b4b7bd_40x40.jpg

配置文件中可以写成这样

location ~ '/images/([0-9a-z]+)_([0-9]+)x([0-9]+).jpg$' {
root /home/images;
set $image_root =  '/home/images';
set $fileName = ngx.arg[1];
set $width = ngx.arg[2];
set $height = ngx.arg[3];
set $origin = $image_root/$fileName.jpg
set $file = $image_root/$fileName_$widthx$height.jpg
if (!-f $file) {
rewrite_by_lua '
local command = "gm convert "..ngx.var.origin.." -thumbnail "..ngx.var.width.."x"
..ngx.var.height.." "..ngx.var.file;
os.execute(command);
';
}

这样就能简单的生成图片指定尺寸的缩略图了。

摘自:http://blog.csdn.net/vboy1010/article/details/7868645

安装lua模块

1、Luajit2.0（推荐）或者 Lua5.1（Lua5.2暂不支持）

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wget http://luajit.org/download/LuaJIT-2.0.0-beta9.tar.gz
tar zxvf LuaJIT-2.0.0-beta9.tar.gz

cd LuaJIT-2.0.0-beta9

make

sudo make install PREFIX=/usr/local/luajit

Note: to avoid overwriting a previous version,

the beta test releases only install the LuaJIT executable under the versioned name (i.e. luajit-2.0.0-beta10).

You probably want to create a symlink for convenience, with a command like this:

sudo ln -sf luajit-2.0.0-beta9 /usr/local/bin/luajit (加上这句命令)

下面需要配置一下 luajit 或 lua 的环境变量(Nginx编译时需要)：

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-- luajit --

# tell nginx's build system where to find LuaJIT:

export LUAJIT_LIB=/path/to/luajit/lib

export LUAJIT_INC=/path/to/luajit/include/luajit-2.0

-- lua --

# or tell where to find Lua if using Lua instead:

export LUA_LIB=/path/to/lua/lib

export LUA_INC=/path/to/lua/include

我的测试环境里，配置如下：

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export LUAJIT_LIB=/usr/local/luajit/lib

export LUAJIT_INC=/usr/local/luajit/include/luajit-2.0