Keepalived+Nginx to achieve high availability (HA)

There are 2 ways of high availability.

1. Nginx+keepalived master-slave configuration

In this scheme, one vip address is used, and two machines are used at the front end, one is the master and the other is ready, but only one machine is working at the same time, and the other backup machine is always in a state of waste when the master machine does not malfunction. For websites with few servers, this scheme is not economical.

2. Nginx+keepalived dual master configuration http://blog.csdn.net/caicongyang/article/details/46468397

In this scheme, two vip addresses are used, two machines are used in the front end, which are active and standby to each other, and two machines are working at the same time. When one machine fails, the request of the two machines is transferred to the burden of one machine, which is very suitable for the current architecture environment and uses DNS polling.

Http://blog.csdn.net/lexang1/article/details/52386909

The HA of keepalived is divided into preemptive mode and non-preemptive mode. When the MASTER recovers from the fault, it will preempt the VIP from the BACKUP node. Non-preemptive mode, that is, after MASTER is restored, it does not preempt the VIP after BACKUP is upgraded to MASTER. The configuration methods of preemptive mode and non-preemptive mode under CentOS7 are described below:

Http://blog.csdn.net/qq_27968607/article/details/60141007

Nginx+Keepalived High availability Cluster

Reference link: https://blog.51cto.com/superpcm/2095395