nginx add dynamic module

    Nginx 增加一個(gè)第三方模塊，需要重新編譯源代碼，所有的模塊都是用靜態(tài)鏈接的形式組織起來的。而 Tengine 可以實(shí)現(xiàn)運(yùn)行時(shí)動(dòng)態(tài)加載模塊，而不用每次都要重新編譯Tengine。

    Nginx 官方發(fā)布的 Nginx-1.9.11 版本，也增加了該功能。?詳看 http://nginx.org/en/CHANGES?

    openresty 的 1.9.15.1 版本也增加了該功能。詳看 http://openresty.org/cn/changelog-1009015.html?

    今天將代碼也更新到了1.9.15.1版本，試著動(dòng)態(tài)加載自己編寫的第三方模塊?

    參考官方文檔：

    Converting Static Modules to Dynamic Modules

    Old Config Shell File

    New Config Shell File

1.Converting a config file?

?old-config:

ngx_addon_name=ngx_http_xxx_filter_module
HTTP_AUX_FILTER_MODULES="$HTTP_AUX_FILTER_MODULES\              
                    ngx_http_xxx_filter_module"
NGX_ADDON_SRCS="$NGX_ADDON_SRCS \
                   $ngx_addon_dir/ngx_http_xxx_filter_module.c"

?new-config:

?ngx_addon_name=ngx_http_xxx_filter_module
#nginx version >= 1.9.11
if test -n "$ngx_module_link"; then   
    if [ $ngx_module_link = ADDON ] ; then          
        ngx_module_type=HTTP_AUX_FILTER   
    fi       
    ngx_module_name=ngx_http_xxx_filter_module    
? ngx_module_srcs="$ngx_addon_dir/ngx_http_xxx_filter_module.c"       
    . auto/module  
#nginx version < 1.9.11
else   
    HTTP_AUX_FILTER_MODULES="$HTTP_AUX_FILTER_MODULES \               
                     ngx_http_xxx_filter_module"    
     NGX_ADDON_SRCS="$NGX_ADDON_SRCS \           
                    $ngx_addon_dir/ngx_http_xxx_filter_module.c"
fi

?ps: 要考慮nginx版本，也要考慮是否為動(dòng)態(tài)模塊

2. Compiling a Dynamic Module?

    A new configure option has been created to add a module as a dynamic module. Instead of using--add-module you use --add-dynamic-module. For example:

    ./configure --add-dynamic-module=/opt/source/ngx_http_xxx_filter_module/?

    Modules are compiled along with NGINX by running the make command. Alternatively you can ask NGINX to just build the modules by doing:

    $ make -f objs/Makefile modules

    With NGINX 1.9.13 the following is another way of doing this:

    $ make modules

?3. Loading a Dynamic Module

     Modules can be loaded into NGINX with the new load_module directive.

     For example:(main級別)

     load_module modules/ngx_http_xxx_filter_module.so;

     ps: 雖說是main級別的，但是要其他塊之上，如：

    user root root;
    worker_processes 2;
    pid /var/run/nginx.pid;

    load_module modules/ngx_http_xxx_filter_module.so;

    events {
        ...?
    }?
    http {
        ...?
    }?

    若load_module用在events與http之間，則會(huì)?提示：

        "load_module" directive is specified too late?

4. note

    4.1 There is a hard limit of 128 dynamic modules that can be loaded at one time, as defined by NGX_MAX_DYNAMIC_MODULES in the NGINX source. This hard limit can be increased by editing this constant.

    4.2 新舊模塊的兼容

        上面已經(jīng)提到了新舊模塊編譯腳本的兼容

        同時(shí)也要考慮c語言層面的兼容，要關(guān)注動(dòng)態(tài)模塊對于 Nginx 框架的調(diào)整

        例如之前凡是用到全局變量 ngx_modules 的地方，要修改為 cycle->modules?

    #if defined(nginx_version) && nginx_version >= 1009011
        modules = cf->cycle->modules;
    #else
        modules = ngx_modules;
    #endif??