tsh aws prepends extra lines to stdout

[Dawnflash]

Expected behavior:

tsh aws s3 ls (or any other AWS CLI command) returns only the output from AWS, eg.

2024-12-15 10:35:32 mybucket

Alternatively any extra lines from teleport should be printed to stderr.

Current behavior:

It returns 2 extra lines in stdout. This is very undesirable when piping forward.

Proxying connections to aws on 127.0.0.1:54277
To avoid port randomization, you can choose the listening port using the --port flag.
2024-12-15 10:35:32 mybucket

Additionally the --port flag referenced refers to the tsh proxy app command which is reused by the tsh aws command apparently and the flag is unusable with the tsh aws command so this is very confusing for the user that might attempt to run tsh aws --port 12345 s3 ls to try to remove the message and be met with "flag not defined". This could use some polishing.

Bug details:

• Teleport version: v16.1.0
• Recreation steps: run tsh aws <anything>

[greedy52]

fixed by #45159