Nginx wiki

因为ngx_str_t默认不是以 \0 结尾的。所以不能直接使用printf来打印。 不过nginx打印日志接口默认提供了一种 %V 的方式。

    ngx_log_debug1(NGX_LOG_DEBUG_HTTP, r->connection->log, 0, "[Test]: big v %V", &(r->method_name));
    ngx_log_debug1(NGX_LOG_DEBUG_HTTP, r->connection->log, 0, "[Test]: big v uri = %V", &(r->uri));

注意这里需要的是ngx_str_t的地址。

https://www.nginx.com/resources/glossary/layer-4-load-balancing/

https://www.nginx.com/resources/glossary/layer-7-load-balancing/

有4层和7层之分。

4层以前用得多，因为7层对计算性能要求较高。

4层就是直接看ip和port，在第四层就开始均衡。不看content的。

7层会看到content，可以根据数据来玩。

    They manage and manipulate traffic based on a full understanding of
    the transaction between the client and the application server.

7层的好处，举个例子：

    Let’s look at a simple example. A user visits a high-traffic
    website. Over the course of the user’s session, he or she might
    request static content such as images or video, dynamic content such
    as a news feed, and even transactional information such as order
    status. Layer 7 load balancing allows the load balancer to route a
    request based on information in the request itself, such as what kind
    of content is being requested. So now a request for an image or video
    can be routed to the servers that store it and are highly optimized to
    serve up multimedia content. Requests for transactional information
    such as a discounted price can be routed to the application server
    responsible for managing pricing. With Layer 7 load balancing, network
    and application architects can create a highly tuned and optimized
    server infrastructure or application delivery network that is both
    reliable and efficiently scales to meet demand.

比如图片个视频的请求可以负载到一个对此优化过的机器上。关于price的请 求可能负载到一个专门处理price的机器上。

自己手动编译的 1.11.3 版本。编译时需要加入 --with-stream 选项。

    ./configure --with-stream

配置如下，把本地的80代理到后端的多个80：

    user  root;
    worker_processes  40;

    events {
        worker_connections  1024;
    }

    stream {
            upstream backend {
                #least_conn;
                #hash $remote_addr;
                server 172.16.2.172:80;
                server 172.16.2.171:80;
                server 172.16.2.7:80;

            }

            server {
                listen        0.0.0.0:80;
                proxy_pass    backend;

                #proxy_bind $remote_addr  transparent;
                #proxy_timeout 3s;
                #proxy_connect_timeout 1s;
                #proxy_set_header X-Forwarded-For $remote_addr;
            }
        }

configure中进来。有些模块需要根据来决定是否启用（如 ngx_http_gunzip_filter_module模块）。

configure会调用到 auto/modules ，这个里面是实际加载哪些模块和模块 调用顺序的。它主要生成了 ngx_modules.c 文件。该文件中定义了 ngx_modules 数组。它指明nginx运行时有哪些模块需要参与，以及它们之 间的顺序是什么。

我们的代码中，是从 txsafe-configure.sh 中进入到configure的。