Show `lstk aws` spinner only for long-running operations by peter-smith-phd · Pull Request #238 · localstack/lstk

peter-smith-phd · 2026-05-10T21:22:40Z

The lstk aws spinner was rendering for every invocation, which looks odd for the common case where the command completes in well under a second. The spinner now waits 4 s before rendering its first frame, so it only appears for operations that are actually slow (e.g. lazy service init). The label is also clarified from "Loading..." to "Loading service..." so the wait is self-explanatory.

Fixed DRG-829

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

carole-lavillonniere · 2026-05-11T07:09:20Z

@gtsiolis can we get your opinion on this change?

gtsiolis

Thanks, @peter-smith-phd! Left some comments below. Once we revert the copy and update the delay duration, we can merge this unless there are any engineering concerns from @carole-lavillonniere.

gtsiolis · 2026-05-11T09:05:04Z

 			stdout, stderr := io.Writer(os.Stdout), io.Writer(os.Stderr)
 			if terminal.IsTerminal(os.Stderr) {
-				s := terminal.NewSpinner(os.Stderr, "Loading...")
+				s := terminal.NewSpinner(os.Stderr, "Service loading...", 4*time.Second)


issue: On the copy change, I'd revert Service loading... back to Loading.....

The first one is more ambiguous and confusing. For example, which service is loading? lstk, docker, localstack, something else?

The verb-based pattern would actually be informative (Creating bucket…, Listing buckets... etc) but isn't possible without overengineering because aws command is a pure proxy.

I was intentionally trying to be more specific, and less vague. The problem is that when I see Loading..., I immediately ask myself "What is loading?". When I use the aws command, I don't expect anything to be loading. I don't expect lstk to be loading, nor do I expect docker or localstack because both of them have been loaded already. It was actually quite confusing to see the Loading... message at all, because I wasn't expecting anything to be loading.

By adding Service loading... we're specifically explaining that the delay is (most likely) due to the emulated service loading. Use of aws is usually very quick and responsive, because that's how AWS designed the APIs. The fact that we're using lazy service loading is what makes it sometimes slow. As an expert user of aws, that extra Service word was important to help me understand why.

Fair point. Could you rename it to Loading service... so it becomes a verb-based label?

gtsiolis · 2026-05-11T09:14:47Z

 			stdout, stderr := io.Writer(os.Stdout), io.Writer(os.Stderr)
 			if terminal.IsTerminal(os.Stderr) {
-				s := terminal.NewSpinner(os.Stderr, "Loading...")
+				s := terminal.NewSpinner(os.Stderr, "Service loading...", 4*time.Second)


thought: Adding a delay before showing a spinner is a common pattern in many UI design systems. In contrast, most CLI and TUI design guidelines or frameworks either recommend printing something as fast as possible to the user or don't expose any delay option at all, with one or two exceptions that also default to zero delay. The deferred spinner sounds ok to add here given the AWS CLI itself does not surface any loading feedback.

gtsiolis · 2026-05-11T09:21:15Z

 			stdout, stderr := io.Writer(os.Stdout), io.Writer(os.Stderr)
 			if terminal.IsTerminal(os.Stderr) {
-				s := terminal.NewSpinner(os.Stderr, "Loading...")
+				s := terminal.NewSpinner(os.Stderr, "Service loading...", 4*time.Second)


suggestion: In CLI design being responsive is more important than being fast[1]. The 4 second window seems unreasonably high. A slow invocation is indistinguishable from a hung CLI. If we're going to add a delay parameter I'd...

Add a smaller delay like 1 second, so the spinner doesn't appear on every AWS command invocation but the silent window is short enough to stay responsive.

Add a minimum visible duration of ~500 ms once the spinner starts, so commands that finish just past the 1 second threshold don't flash a single frame.

Skip [2] if slow AWS invocations always overshoot 1 scond by a meaningful margin which is true from what I've seen.

I did think about 3 seconds initially, but when I did some practical experiments it felt like 4 seconds was the time at which I start to think "this is taking a while". Normally, the aws command doesn't show any spinners, nor would customers expect aws commands to take more than a few seconds.

I feel that 1 second is far too short, as the user will see the spinner even on "normal" AWS calls - that is, when there is no lazy-loading actually happening.

Following up from #238 (comment), we can also keep the 4 seconds for now and adjust later.

gtsiolis · 2026-05-11T09:40:53Z

 			stdout, stderr := io.Writer(os.Stdout), io.Writer(os.Stderr)
 			if terminal.IsTerminal(os.Stderr) {
-				s := terminal.NewSpinner(os.Stderr, "Loading...")
+				s := terminal.NewSpinner(os.Stderr, "Service loading...", 4*time.Second)


suggestion: Just to confirm, this adds the delay only for aws commands, right?

~~The delay is only added to the non-TTY (aka non-TUI/non-bubbletea) spinner which is only used for the aws command at the moment. However it would be applied to any other future use case.~~
Taking this back. The delay can be configured so whether the spinner should appear after a delay or not can be decided on a command basis 👏

Yes, this needs to be configurable for each command. The proposed message Service loading... and the delay of 4 seconds only makes sense in the context of aws. For other commands there would be different messages and different delays.

carole-lavillonniere

Good to go from a code perspective once @gtsiolis is happy, well done @peter-smith-phd

gtsiolis

Looks shippable.

Updated PR description to use the new copy.

Thanks for contributing, @peter-smith-phd! 🏀

Show lstk aws spinner only for long-running operations

134fc28

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

peter-smith-phd added the semver: patch label May 10, 2026

peter-smith-phd marked this pull request as ready for review May 10, 2026 21:32

peter-smith-phd requested review from anisaoshafi, carole-lavillonniere and silv-io as code owners May 10, 2026 21:32

gtsiolis requested changes May 11, 2026

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carole-lavillonniere approved these changes May 11, 2026

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Changes based on PR feedback.

74c3b7c

peter-smith-phd requested a review from gtsiolis May 11, 2026 19:59

Merge branch 'main' into drg-829-aws-spinner-duration

3540545

gtsiolis approved these changes May 11, 2026

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peter-smith-phd merged commit 75d456b into main May 11, 2026
12 checks passed

peter-smith-phd deleted the drg-829-aws-spinner-duration branch May 11, 2026 21:57

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peter-smith-phd commented May 10, 2026 •

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