NLB doesn't send traffic to new healthy Fargate tasks
I have ECS with Fargate. Traffic is routed with NLB. When service is just started NLB routes traffic equally to all tasks with no problem. However, when service is automatically sales up (or if I manually increase tasks count) NLB is not routing traffic to a newly created tasks. Despite the fact that new task are marked as healthy in a Target group. I can see it clearly form new tasks log and from "about zero" minimum CPU on the Service.
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Hi Smotrov, I understand that you have ECS Fargate tasks which are being load balanced using an NLB with a Target Group configured for IP Registration. However, connections are not being routed to the new healthy tasks as they are registered with the target group. In the NLB overview section of AWS Docs you will find that each individual TCP connection is routed to a single target for the life of the connection. With ALB you can specify the load balancing algorithm of either round robin or least outstanding requests.
This question was answered live in great detail at twitch https://www.twitch.tv/aws/video/1420471067.
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I presume they are all registering with IP, not instance ID in the target group. This is the default in Fargate. Are they in an AZ that the NLB is not configured to support?
Yes, NLB is available in the same 3 AZ as tasks. And yes, they are registered with IP.
Do you have sticky sessions enabled? How are you testing the routing?
Hello Smotrov, has your issue been resolved? If not, can you reply to Ben's questions? Thank you for your participation in AWS re:Post community.