Assign indices or other identifier to each container behind an ALB, and use this to track requests

[malini]

Is your feature request related to a problem? Please describe.
From Mel, regarding multiple containers behind an ALB: “It would be nice if we could assign them indexes and expose what server is acting on the request in the response headers 😄 Like a X-Thunderbird-Server-Id for debug purposes.”

[ryanjjung]

This is interesting. When we tell the containers to run, it's by defining a task definition (container sizing, image, environment stuff) and a desired scale ("I want 3 instances of this running"). So there's not a great deal of control over the individual containers.

The containers are identified to the load balancer by IP address. Over time, with several container replacements, some IPs might get reused, so using that as an identifier wouldn't provide this feature forever, but in correlation with a timestamp it becomes meaningful.

Another option might be to have the applciation itself generate a random UUID on launch and tag all its responses with that UUID.

[ryanjjung]

The containers all have IDs at the AWS API level. I wonder if that information is available internally within the container. That would probably be the most useful data for isolating log files as well.