Section 12: Scaling the FortiGate Auto Scaling Group from FortiManager

In this section, you will scale the FortiGate Auto Scaling Group by using FortiManager.

You will perform two operations:

1. Scale out the Auto Scaling Group to increase the number of FortiGate-VM instances.
2. Scale in the Auto Scaling Group to reduce the number of FortiGate-VM instances.

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Objectives

By the end of this section, you will be able to:

• Locate the FortiGate Auto Scaling device group in FortiManager.
• Use Auto-Scale Instance Count from FortiManager.
• Scale out the Auto Scaling Group by increasing the instance count.
• Scale in the Auto Scaling Group by decreasing the instance count.
• Verify that FortiGate-VM instances are added or removed.
• Understand that scaled-in FortiGate-VM entries may require manual cleanup in FortiManager.

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Part 1: Scale Out the Auto Scaling Group

Start with 2 healthy FortiGates. In FortiManager, use Auto-Scale Instance Count to increase the desired count to 3. The deployment must be in active stage after Section 10, with an effective ASG maximum of at least 3, and the FortiFlex configuration must have capacity to license the third device.

In Device Manager → Device & Groups, right-click the UMS ASG group and choose Auto-Scale Instance Count. Following the Fortinet procedure, set minimum, desired and maximum to 3 to force the three-node exercise, then confirm the change. This changes the live AWS ASG bounds from the Terraform baseline.

Before scaling, confirm the onboarding rule already assigns the GWLB-Web-Templates group and populated GWLB-Web-Demo package. After scaling:

1. Wait for the new instance to register and receive a license.
2. Confirm provisioning and policy-package installation succeed on the new device.
3. Wait for its GWLB target health to become healthy.
4. Open the existing web-demo URL and select Start traffic. A third card appears automatically; it flashes after matched traffic reaches that device. Healthy status alone does not produce a flash. GWLB hashing and AZ eligibility can make traffic uneven.

Use FortiManager for this exercise. A new Terraform plan can propose restoring minimum/desired/maximum to the configured 2/2/3 after a UMS change. Review those differences before applying; do not use Terraform to install FortiManager policies or reuse a saved plan from before scaling.

Follow the steps in the official Fortinet documentation below:

Scale Out the Auto Scaling Group

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Part 2: Scale In the Auto Scaling Group

Scaling in reduces the number of FortiGate-VM instances in the Auto Scaling Group.

In this example, the Auto Scaling Group will be scaled in from 3 FortiGate-VM instances back to the 2-instance baseline. Open Auto-Scale Instance Count again and set minimum, desired and maximum to 2, then confirm. The maximum is now 2; raise it again when repeating scale-out.

Follow the steps in the official Fortinet documentation below:

Scale In the Auto Scaling Group

Wait for scale-in to finish, then confirm the remaining two targets are healthy and the demo remains reachable. The removed member disappears on the next successful inventory refresh. Review any stale FortiManager entries before manual cleanup; do not remove a device that is still active.