First, introduce rolling release
Rolling release (rolling update) is the most common type of release mode. For example, I have 10 machines, to deploy a one of. When each machine deployment, the need to ensure that no request will be distributed to the machine, otherwise the user will see a 502 error. Therefore, there is a need for "downline" operation, the current extraction from the load balancing machine, and then after the deployment is complete, and then return to their hanging load balancing, this process is called "on line." Next will explain, with Ali cloud SLB how to cook / drop operation.
Two, SLB configuration
