Welcome to session three, Scaling Groups. In this session, we will look at creating, modifying, enabling, disabling, and finally deleting the scaling group. Correct scaling group is pretty straightforward and can be done from the Auto Scaling homepage within the console by clicking the Create Scaling Group button. This will open the quick create template list or from the scaling group list page by clicking the Create button.

Whichever method is used the main configuration points for a scale group are: Give the scale group a name and choose the configuration source. Optionally configure tags, configure the instance removal policy enter the minimum and maximum number of instances allowed in the group. Configure the default cool down time, select the scaling policy and reclaim mode, select the network and V-Switches that the ECS instances will be provisioned in and optionally select any server load balancers and RDS instances that we want to associate with the scale group.

It's worth noting that a scale group can exist even if it doesn't have a load balancer or RDS instance attached. Once created, the scale group will be provisioned in a disabled state until a scale configuration is added. Querying and modifying scale groups. We also need to be able to query and modify a scale group. So scaling groups have three life cycle states: Active, inactive, and deleting.

\When you're modifying scaling groups the following cannot be modified: The region, server load balancer settings, RDS database settings. But the following can be modified: Tags, instance removal policy, suspended processes, deletion protection, health check setting, cool down period and minimum or maximum number of ECS instances allowed in the group.

It's worth noting that if the number of ECS instances in the scale group doesn't meet the new minimum number or maximum number settings, Auto Scaling will create a scaling activity to either add or remove ECS instances to or from the group until the minimum or maximum count value is reached. Modify operations can only be executed for scale groups that are in an active or inactive state.

Enabling and disabling scaling groups. For enabling, you can only enable an inactive scale group if it has an active scaling configuration. A single scale group can have only one active scaling configuration at a time, although it can also have several inactive scaling configurations that you could replace the active one with. You can enable a scale group, such that if an existing number of ECS instances is less than the minimum size value of an enabled or active scale group, then Auto Scaling will create new pay You go ECS instances until the minimum size value is reached. And for disabling, a scale group can only be disabled when it is not executing any scaling activity. And this operation can only be executed for active scaling groups.

I do want to point out that any operations that take place within a scale group can trigger CloudMonitor event notifications or messages from the message notification service if an event notification has been created. This is so that you can be notified when a state change occurs in your scale group, either by email or by SMS. You can also enable what are called lifecycle hooks which means that when an instance is added or removed from your instance pool, you can have certain operations take place on that instance to set it up prior to service requests or potentially to finish up any requests that the instance was handling before it's removed from the pool and released.

Deleting scaling groups. When you delete a scale group from the console, it's deleted in ForceDelete mode. Deleting the scale group also deletes its: Scaling configurations, scaling rules, scaling activities, and scaling requests. Deleting the scale group does not delete scheduled tasks, any server load balancer instances or RDS instances that were attached to the group. These items all live outside of the group. That concludes the session on scaling groups. In the next session, I'll demonstrate how to create a scale group.