CloudFormation + Load Balancer Controller results in System Tag issue

[zac-nixon]

ELBv2 recently added support for system tagging, which means that ALBs and NLBs provisioned using Cloudformation will have system tags attached to them. Users that provision their Loadbalancer using Cloudformation but then pass management over to the Load Balancer Controller may see errors such as this in their controller logs:

Tag key 'aws:cloudformation:logical-id' cannot start with 'aws:'

The fix for this is to utilize the external-managed-tags deployment flag for the Load Balancer Controller.

--external-managed-tags=aws:cloudformation:logical-id,aws:cloudformation:stack-id,aws:cloudformation:stack-name

We also have a fix queued up for release v3.2.0 which does this automatically. 672b199