Hello team,
The attached file has the steps to show how to deploy a Hot Standby FortiGate HA in AWS using CloudFormation template. A simplistic diagram is also attached to visialize what is being deployed.
Since there is no access to Layer 2 in AWS, a workaround needs to be in place to have automated High Availability in HA.
-The CloudFormation template assumes that the account that is deploying this has a Route53 domain name. This is needed to access the active firewall using a DNS name.
-There is a t2.micro AWS instance(Worker Node) that gets created with the stack. This is where the python script to monitor the active firewall is run from.
-If the primary FortiGate becomes unavailable, the required AWS API calls are made to disassociate the subnets from the Primary Firewall's Route Table and associate them to the Backup Firewall's Route Table. Once this is done, a continious check is done to see if the Primary instance comes back up. Once it is backup, all the subnet associations are made back to the Primary Firewall's Route Table.
-(Optional) The Worker Node can also be made part of a AutoScaling Group.
-(Optional)The Worker node can be run from any server anywhere as long as it has AWS CLI tools and python loaded on it.
