This repository was archived by the owner on Mar 23, 2026. It is now read-only.
CFn: configure wait time for polling resources#13455
Merged
Conversation
simonrw
added
semver: patch
simonrw
commented
Dec 2, 2025
localstack-core/localstack/config.py
Outdated
| CFN_IGNORE_UNSUPPORTED_RESOURCE_TYPES = is_env_not_false("CFN_IGNORE_UNSUPPORTED_RESOURCE_TYPES") | ||
|
|
||
| # Decrease the waiting time for resource deployment | ||
| CFN_NUM_NO_WAIT: str | int | None = os.environ.get("CFN_NUM_NO_WAIT") |
Contributor
Author
There was a problem hiding this comment.
I am not happy with this name. Any better ideas?
Contributor
Author
There was a problem hiding this comment.
Yeah that's better, thanks!
S3 Image Test Results (AMD64 / ARM64) 2 files 2 suites 8m 13s ⏱️ Results for commit ecee01c. ♻️ This comment has been updated with latest results. |
Test Results - Alternative Providers587 tests 331 ✅ 18m 11s ⏱️ Results for commit ecee01c. ♻️ This comment has been updated with latest results. |
simonrw
added
docs: needed
Test Results (amd64) - Integration, Bootstrap 5 files 5 suites 2h 33m 43s ⏱️ Results for commit ecee01c. ♻️ This comment has been updated with latest results. |
simonrw
requested review from
dominikschubert,
pinzon and
thrau
as code owners
simonrw
force-pushed
the
cfn/configurable-sleep-time
branch
2 times, most recently
from
263dad2 to
c299bf7
Compare
pinzon
approved these changes
Dec 3, 2025
localstack-core/localstack/config.py
Outdated
| CFN_IGNORE_UNSUPPORTED_RESOURCE_TYPES = is_env_not_false("CFN_IGNORE_UNSUPPORTED_RESOURCE_TYPES") | ||
|
|
||
| # Decrease the waiting time for resource deployment | ||
| CFN_NUM_NO_WAIT: str | int | None = os.environ.get("CFN_NUM_NO_WAIT") |
pinzon
reviewed
Dec 3, 2025
| if current_iteration == 0: | ||
| time.sleep(0) | ||
| # This should have been set up in the provider | ||
| assert isinstance(config.CFN_NUM_NO_WAIT, int) |
Member
There was a problem hiding this comment.
Question: is it necessary to assert this in every iteration?
Contributor
Author
There was a problem hiding this comment.
That's a fair point, thanks!
simonrw
force-pushed
the
cfn/configurable-sleep-time
branch
from
c299bf7 to
35bd89f
Compare
Since we perform 5 updates in quick succession, we probably want to use a higher number of minimum iterations
simonrw
force-pushed
the
cfn/configurable-sleep-time
branch
from
35bd89f to
ecee01c
Compare
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to subscribe to this conversation on GitHub.
Already have an account?
Sign in.
2 participants
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
Motivation
While deploying our re:Invent demo stack I found it takes ~85 seconds for a warm deploy on my system. This time is dominated by deploying lambda functions which each take 5 seconds.
When we deploy resources, we create a loop where
AWS CloudFormation waits between polling loops (to reduce burden on their networking and services). On LocalStack we don't need to do this - a lot of our resources are in-memory so are instantly available. Therefore we set the sleep time for the first iteration of this loop only to 0 seconds, and wait 5 seconds for every other iteration.
Since the lambda functions take a minimum of 5 seconds each, I suspect the deployment loop is going round more than twice.
Increasing the number of loop iterations that we don't sleep for would reduce this deployment time greatly.
Changes
CFN_NO_WAIT_ITERATIONSto control the number of loop iterations we don't wait 5 seconds between, defaulting to 5 iterationsCFN_PER_RESOURCE_TIMEOUTof e.g. 0!)After these changes, our re:Invent demo stack takes ~30 seconds, leading to a 2.8x total speedup 🎉
Tests
1, and with the new default of5and observe the total time to deploy has decreasedRelated
Resolves UNC-122