Nginx basic function example analysis

1. Static http server

First of all, nginx is an http server that can display static files (such as html and pictures) on the server to the client through the http protocol. Configuration:

server {

  listen 80; # 端口号

  location / {

    root /usr/share/nginx/html; # 静态文件路径

  }

}

2. Reverse proxy server

What is a reverse proxy?

The client can directly access a website application server through the http protocol. The website administrator can add an nginx in the middle. The client requests nginx, nginx requests the application server, and then returns the result to the client. This nginx is a reverse proxy server.

Configuration:

server {

  listen 80;

  location / {

    proxy_pass http://192.168.20.1:8080; # 应用服务器http地址

  }

}

Since the server can be directly accessed via http, why should we add a reverse proxy in the middle? Isn’t it unnecessary? What does a reverse proxy do?

Continuing to look down, the following load balancing, virtual host, etc. are all based on reverse proxy. Of course, the functions of reverse proxy are not only these.

3. Load Balancing

When the website traffic is very large, the webmaster is happy to make money, but at the same time he is also in trouble. Because the website is getting slower and slower, one server is no longer enough.

So the same application is deployed on multiple servers, and requests from a large number of users are distributed to multiple machines for processing. At the same time, the benefit is that if one of the servers crashes, as long as other servers are running normally, it will not affect the user's use. nginx can achieve load balancing through reverse proxy.

Configuration:

upstream myapp {

  server 192.168.20.1:8080; # 应用服务器1

  server 192.168.20.2:8080; # 应用服务器2

}

server {

  listen 80;

  location / {

    proxy_pass http://myapp;

  }

}

The above configuration will allocate request polling to the application server, that is, multiple requests from a client may be processed by multiple processed by different servers. You can use ip-hash to assign requests to a fixed server for processing based on the hash value of the client's IP address.

Configuration:

upstream myapp {

  ip_hash; # 根据客户端ip地址hash值将请求分配给固定的一个服务器处理

  server 192.168.20.1:8080;

  server 192.168.20.2:8080;

}

server {

  listen 80;

  location / {

    proxy_pass http://myapp;

  }

}

In addition, the hardware configuration of the server may be good or bad. If you want to allocate most requests to good servers and a small number of requests to poor servers, you can use weight to control.

Configuration:

upstream myapp {

  server 192.168.20.1:8080 weight=3; # 该服务器处理3/4请求

  server 192.168.20.2:8080; # weight默认为1，该服务器处理1/4请求

}

server {

  listen 80;

  location / {

    proxy_pass http://myapp;

  }

}

4. Virtual host

Some websites have a large number of visits and require load balancing. However, not all websites are so excellent. Some websites need to save costs by deploying multiple websites on the same server because the number of visits is too small.

For example, if two websites www.aaa.com and www.bbb.com are deployed on the same server, the two domain names resolve to the same IP address, but the user can open both through the two domain names. Completely different websites do not affect each other, just like accessing two servers, so they are called two virtual hosts.

Configuration:

server {

  listen 80 default_server;

  server_name _;

  return 444; # 过滤其他域名的请求，返回444状态码

}

server {

  listen 80;

  server_name www.aaa.com; # www.aaa.com域名

  location / {

    proxy_pass http://localhost:8080; # 对应端口号8080

  }

}

server {

  listen 80;

  server_name www.bbb.com; # www.bbb.com域名

  location / {

    proxy_pass http://localhost:8081; # 对应端口号8081

  }

}

Open an application on servers 8080 and 8081 respectively. The client accesses through different domain names and can reverse proxy to the corresponding application server according to the server_name.

The principle of virtual host is realized by whether the host in the http request header matches the server_name. Interested students can study the http protocol.

In addition, the server_name configuration can also filter out someone who maliciously points certain domain names to your host server.

5, fastcgi

nginx itself does not support languages ​​​​such as php, but it can throw requests to certain languages ​​​​or frameworks through fastcgi (such as php, python , perl).

server {

  listen 80;

  location ~ \.php$ {

    include fastcgi_params;

    fastcgi_param script_filename /php文件路径$fastcgi_script_name; # php文件路径

    fastcgi_pass 127.0.0.1:9000; # php-fpm地址和端口号

    # 另一种方式：fastcgi_pass unix:/var/run/php5-fpm.sock;

  }

}

In the configuration, requests ending in .php are handed over to php-fpm for processing through fashcgi. php-fpm is a fastcgi manager of PHP. You can check other information about fashcgi, which will not be introduced in this article.

What is the difference between fastcgi_pass and proxy_pass? The following picture will help you understand:

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