A target group routes requests to targets (e.g. instances or Kubernetes service).
First, a listener rule is creates which specifies the target group and conditions. i.e. when a rule condition is met, traffic is forwarded to the target group.
For more on
Target Group Attributes
Slow Start Mode
Create a Target Group
Health Checks for Your Target Groups
Register Targets with Your Target Group
Tags for Your Target Group
Delete a Target Group
Sticky sessions route requests to the same target in a target group. To use sticky sessions, the clients must support cookies. Useful for stateful apps.
Note: WebSockets are inherently sticky ‘cos target returns an HTTP 101 (Switching Protocols: https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/101 ) and then, after WebSockets upgrade is complete, cookie-based stickiness is not used.