upstream

1、轮询

2、加权循环

• weight=number默认是加权循环，先按weight的权重分配，
• max_fails最大失败次数2次，失败超时时间30s，失败找其他的机器 默认权重是1
• fail_timeout 超时失败时间
• backup 之前所有的访问都失效开始尝试backup

upstream backend {
  server 127.0.0.1:8080 weight=1 max_fails=2 fail_timeout=30s;
  server 192.168.1.1:8080 weight=1 max_fails=2 fail_timeout=30s backup;
}

3、ip_hash

ip_hash确保同一个客户端的ip每次都去同一台服务器

down 当前server不参加负载

upstream backend {
    ip_hash;

    server backend1.example.com;
    server backend2.example.com;
    server backend3.example.com down;
    server backend4.example.com;
}

4、hash

5、least_conn

最小活动连接数，权重的负载均衡

upstream backend {
    least_conn;

    server backend1.example.com;
    server backend2.example.com;
}

6、least_time header|last_byte;

响应时间最短，活动连接数

upstream backend {
    least_time header;

    server backend1.example.com;
    server backend2.example.com;
}

推荐使用：加权循环

upstream backend {
  server 127.0.0.1:8080 weight=1 max_fails=2 fail_timeout=30s;
  server 192.168.1.1:8080 weight=1 max_fails=2 fail_timeout=30s backup;
}