Impact of preview-scoped environment variables in AEM as a Cloud Service
Adding new configuration environment variables scoped to the Preview tier in AEM as a Cloud Service production environment causes only the Preview instance to briefly restart. This action does not cause downtime for Publish or Dispatcher tiers, which use rolling, no-downtime update patterns.
Description description
Environment
- Product: Adobe Experience Manager as a Cloud Service - Sites
- Instance:Â Production
Issue/Symptoms
- When adding a preview-scoped environment variable in a production environment, the Preview tier briefly restarts. This behavior is expected and limited to the Preview instance.
- Publish and Dispatcher tiers are not impacted and continue to serve traffic normally.
Resolution resolution
Note: Preview runs as a single instance, so it experiences a brief interruption during updates. Publish and Dispatcher tiers use rolling updates that maintain availability and avoid planned downtime for end-user traffic.
Follow these steps to implement the preview‑scoped environment variable change:
- Open Cloud Manager and go to Program
>Environments>[PROD]>Configuration. - Add the required environment variable name and value.
- Set Step Applied to Preview, not All, Author, or Publish.
- Apply the change and verify the behavior in DEV first, then STAGE.
- After validation, apply the same preview-scoped environment variable in PROD.
- Schedule the PROD update during a low-traffic window.
- Inform internal users that the Preview instance will restart briefly.
- Monitor production and capture timestamps, URLs, and HTTP status codes if 5xx errors appear.
- Confirm that only the Preview tier restarts and that Publish and Dispatcher remain available.
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