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az containerapp update resets template.scale.cooldownPeriod to 300 #10334
Description
Activity
Thank you for opening this issue, we will look into it.
microsoft-github-policy-service commented
on Oct 4, 2026 ContributorThanks for the feedback! We are routing this to the appropriate team for follow-up. cc Hong Wang (@howang-ms), Greedygre (@Greedygre), @Azure/act-observability-squad.
Bug Analysis
The report supplies enough context for a scoped fix: an app starts with
properties.template.scale.cooldownPeriod = 3600, then an image-onlyaz containerapp updatechanges it to300. An unrelated image deployment should preserve the configured scaling settings, regardless of whether Terraform originally created the app.Source evidence: on extension
mainatd106f8dce117a3d2bf598cdf3a9b2b90faeb0f9d,ContainerAppUpdateDecorator.construct_payloadstarts a fresh properties object and copies containers for an image update. Scale is considered an update only when replica or scale-rule arguments are supplied; the scale block does not carry forward the existing cooldown. The update boundary passes that partial payload to the inherited raw PATCH client. Thus the image-only payload omits the persisted scale configuration. This confirms a request-construction gap, not an Agent reproduction of the service's reported reset.Fix scope: preserve the effective existing scale settings when updating the revision template, while letting explicitly requested changes win. Retain cooldown, polling interval, replica bounds and scale rules without introducing default values. Preserve YAML and
--from-revisionbehavior, and avoid copying unrelated read-only resource properties or changing API versions.Coverage: exercise the real update/decorator-to-client boundary with a persisted cooldown of
3600and an image-only update; assert both the changed image and preserved scale payload. Include explicit replica/rule overrides, missing scale, and existing-rule cases. Add a focused scenario that provisions non-default scale settings, deploys a new image and asserts those settings remain unchanged. Live Azure evidence and recordings must come from the governed Tester workflow.PR title: [Container Apps] Fix #10334:
az containerapp update: Preserve the configured cooldown period during image updatesPosted by x-engineering-agent (Fixer)
Describe the bug
Our Container App is provisioned with Terraform using
cooldown_period_in_seconds = 3600. The deployed app initially reportsproperties.template.scale.cooldownPeriodas3600.After we run
az containerapp updateto deploy a new image, the value changesto the default of
300, even though the update command does not specify acooldown period.
Related command
az containerapp update -g -n![]()
:
--image /
Errors
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Issue script & Debug output
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Expected behavior
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Environment Summary
azure-cli 2.88.0 *
core 2.88.0 *
telemetry 1.1.0
Dependencies:
msal 1.36.0
azure-mgmt-resource 24.0.0
Python location '/usr/bin/python3.12'
Config directory '/root/.azure'
Extensions directory '/root/.azure/cliextensions'
Python (Linux) 3.12.9 (main, Jun 2 2026, 15:09:20) [GCC 13.2.0]
Legal docs and information: aka.ms/AzureCliLegal
Additional context
No response