Auto-prompt mode breaks non-interactive aws usage

[joehorsnell]

Describe the bug

Enabling the auto-prompt feature, eg using AWS_CLI_AUTO_PROMPT=on, breaks non-interactive use of aws, such as invoking from a script.

A couple of related issues, #5317 and #7862, have comments suggesting the use of on-partial, eg using AWS_CLI_AUTO_PROMPT=on-partial, but this is really a workaround.

The AWS CLI should check if it's being invoked interactively, eg checking for a tty, and conditionally disable auto-prompt mode, as you should only ever want that behaviour when running interactively.

Expected Behavior

aws should work correctly non-interactively (eg when invoked from a script) by disabling auto-prompt mode if it's on.

Current Behavior

aws displays the auto-prompt when invoked non-interactively, eg from a script, rather than running the desired command, breaking the script.

Reproduction Steps

Enable auto-prompt mode, using export AWS_CLI_AUTO_PROMPT=on and run any aws command from a script.

Possible Solution

As per description, check for a tty.

Additional Information/Context

No response

CLI version used

aws-cli/2.13.35 Python/3.11.6 Darwin/21.6.0 exe/x86_64

Environment details (OS name and version, etc.)

macOS Monterey 12.7

[joehorsnell]

I had a quick poke around to see how easy this would be to fix and noticed that the initial implementation of auto-prompt in #5613 did have checks for TTY (here and here), but they were removed in #5635, which added the on-partial mode.

I'd say that's still a bug as, by definition, both auto-prompt modes (on and on-partial) are for interactive use, where a user is there to select an option if prompted. Non-interactive use should disable any auto-prompting mode, if enabled, as it can never work.

[tim-finnigan]

Hi @joehorsnell thanks for reaching out. Could you elaborate a bit more on why on-partial mode does not meet the requirements for your use case? Per the documentation that mode is intended for use cases involving pre-existing scripts:

on-partial uses partial auto-prompt mode. If a command is incomplete or cannot be run due to client-side validation errors, auto-prompt is used. This mode is particular useful if you have pre-existing scripts, runbooks, or you only want to be auto-prompted for commands you are unfamiliar with rather than prompted on every command.

[joehorsnell]

Hi @tim-finnigan - thanks for getting back to me.

I do indeed have on-partial mode enabled now, after debugging the problem before opening the bug report.

In answer to your question, what if you wanted to always have auto-prompt for interactive use, but also be able to still use aws in scripts non-interactively? Or in other words, why have the on mode at all and only have on-partial mode, since the on mode currently is a bit of a foot gun?

I understand that this might not be deemed a priority to fix and this issue will probably end up getting automatically closed by the stale bot, but it is still a bug, so suggest you leave it labelled as such, even if it get closed as stale or "won't fix".

[tim-finnigan]

Thanks for following up - I think we can keep tracking this for now, it would be good to get further input from the team. There are issues like #8370 where the current behavior could potentially be improved or better documented.

[joehorsnell]

Hi @tim-finnigan - yep, exactly - #8370 is, as you say, the same problem.

To recap, the basic issue is that both variants of the auto-prompt mode (on and on-partial) are only for interactive use and you never want auto-prompt, in any guise, enabled for script usage. The simplest solution I think is just to always check for a tty, to determine if aws is being invoked interactively, and fully disable auto-prompt if not.

I don't think it would be too difficult to fix, as per my comment above, the original implementation had much of the required code checks in it. I would potentially have a look at fixing it myself, if I knew that a PR would likely be accepted?