An L7 load balancer target group is a set of IP addresses of VMs that your network applications are running on. To enable the load balancer to distribute routing requests between the VMs of the target group, specify it in the backend group configuration.
You can create target groups:
- Manually. In this case, if you change the VM internal IP address, for example, when moving it to another subnet, make sure to update the target group: first remove the VM and then add the modified VM back to it.
- Using Instance Groups. When you change the VM configuration, Instance Groups automatically updates IP addresses of VMs in the target group. If the target group is connected to a backend group, Instance Groups also monitors health check results delivered by the L7 load balancer.
If a target group is used in at least one backend group, you cannot delete it. First, you need to delete it from all backend groups.