Nginx分发算法实现

1、基于轮询分发：根据请求流量均匀分发到后端服务器

upstream web {
    server server1; 
    server server2;
}
server {
    listen 80;
    server_name localhost; 
    location / {
        proxy_pass http://web;
    } 
}

2、基于主备分发：默认分发到主，主宕机后分发到备

upstream web {
    server server1; 
    server server2 backup;
}
server {
    listen 80;
    server_name localhost; 
    location / {
        proxy_pass http://web;
    } 
}

3、基于权重：通过配置权重，可以让性能好的服务器承担更多的负载

upstream web {
    # 设置权重比例1:2
    server server1 weight=1; 
    server server2 weight=2;
}
server {
    listen 80;
    server_name localhost; 
    location / {
        proxy_pass http://web;
    } 
}

4、基于ip_hash分发：保证来自同样源地址的请求都分发到同一台主机

upstream web { 
    ip_hash;    # 指定ip_hash即可，默认weight权重比例1: 1
    server server1;
    server server2; 
}
server { 
    listen 80;
    server_name localhost; 
    location / {
        proxy_pass http://web;
    } 
}

需要注意：ip_hash算法不支持backup、weight设置。默认权重为1