Managing Instance groups on VMs

 

In this article, we are going to see about what is Instance groups and how you can use instance groups to manage a group of virtual machine instances.

Instance group allows your applications to gracefully handle increase in traffic as well as it reduces the cost when the need for the resource is lower. And we will see about types of instance groups and the features of instance groups in this article.

What is Instance Groups?

Instance group is nothing but a group of virtual machine instances managed as a single entity. You can manage groups of similar VMs having similar life cycle as one unit and you can create two types of Instance group in Compute Engine.

They are:

1. Managed instance group.

2. Unmanaged Instance group

1. Managed Instance group (MIG)

These are identical virtual machine created using instance template. So these VMs, which are part of managed group will have same machine type, same image and the same configuration.

Some of the features that are provided for the managed instance group include auto scaling based on the number of users using the instance group, you can scale the number of compute instances up and down.

Managed instances also provide an auto healing. You can configure a health check, and if the health check fails that specific instance would be automatically replaced with a new instance.

Another important features of MIG is managed releases. In this you can go from one version to another version without any downtime.

Important Features of MIG:

It can maintain a certain number of Instances.

Example: If, in case any one of the instances in the instance group fails, the managed instance group will replace that instance with a new instance. Therefore if an instance crashes, the managed instance group will launch another instance.

It can "detect application failures" using health checks. So basically, you can configure a health check on the application which is deployed on your instance. And if the health check fails, that instance will be replaced by a new instance.

Feature Name: Self Healing

You can also increase and decrease the number of instances that are part of your managed instance group, based on the number of users using the application.

Feature Name: Auto Scaling

You can also add a load balancer attached to your managed instance group to distribute load among the different VMs that are part of your management group.

Feature Name: Load balancer

And if you are creating regional managed instance groups, then you can distribute the instances across multiple zones. This gives your higher availability. So regional managed groups provide higher availability compared to zonal MIGs.

Feature Name: Regional MIGs

The other important feature of managed instance group is that you release new application versions without downtime.

Feature Name: Rolling Updates

Managed Instance groups are maintained by Compute Engine and it will specify the instance template based on the configuration for scaling purposes.

Advantages of using Managed Instance groups

Managed Instance groups offer:

1. High Availability: High availability consists of Regional coverage, Auto healing, and load balancing to distribute the traffic.

2. Scalability: Managed Instance group automatically scales the number of instances according to their demand and scales down to reduce the costs.

3. Automatic updates: it consists of rolling updates and canary deployment. It helps to update the instances without disrupting the service.

4. It also supports stateful workloads.