2 ELBs (ALBs) to 1 target group, possible?

Solution 1:

I'm not sure if you can point two ALBs to a single TargetGroup. However since you mentioned AutoScaling you can have the ASG instances automatically registered in more than one TargetGroups, therefore your approach with two target groups will work just as well with AutoScaling.

Hope that helps.

UPDATE #1

The OP was able to find this link to AWS docs on limits titled: Limits for Your Application Load Balancers. In this docs on limits the number of target groups per ALB is mentioned in this table:

Target Group Limits

• Load balancers per target group: 1
• Targets per target group (instances or IP addresses): 1000
• Targets per target group (Lambda functions): 1

Based on this info, you cannot have the same target group in more than one ALB.