nginx_lua配合GraphicsMagick实时创建缩略图的nginx配置文件

server
{
    listen  80;
    server_name test.anerg.com;
    root /data/www/imgtest;
    index default.html default.php index.php index.html;

  location /images/ {
        set $needCreateImg 0;
        if (!-f $request_filename) {
            set $needCreateImg "${needCreateImg}1";
        }

        if ($uri ~* "/images/([0-9a-zA-Z]+)_(\d+x\d+).(gif|jpg|jpeg|png)") {
            set $needCreateImg "${needCreateImg}2";
        }

        if ($needCreateImg = "012") {
            set $filePath "$document_root/images/$1_$2.$3";
            set $originalPath "$document_root/images/$1.$3";
            set $fileSize "$2";
            set $fileExt "$3";
            set $reqFile "$1_$2.$3";

            rewrite_by_lua '
                function file_exists(name)
                   local f=io.open(name,"r")
                   if f~=nil then io.close(f) return true else return false end
                end
                local image_sizes = {"155x155", "400x400","104x104", "50x50", "40x40", "56x56", "172x172","800x600"};
                function table.contains(table, element)
                    for _, value in pairs(table) do
                        if value == element then
                            return true
                        end
                    end
                    return false
                end

                if table.contains(image_sizes, ngx.var.fileSize) and file_exists(ngx.var.originalPath) then
                    local command = "gm convert " ..  ngx.var.originalPath  .. " -thumbnail " .. ngx.var.fileSize .. " -background white -gravity center -extent " .. ngx.var.fileSize .. " " .. ngx.var.filePath;
                    os.execute(command);
                    ngx.req.set_uri("/images/" .. ngx.var.reqFile, true);
                else
                    ngx.exit(404);
                end;
             ';
        }


    }

    location = /favicon.ico {
        log_not_found off;
        access_log off;
    }
}