Public Preview: Azure Functions zero-downtime deployments with rolling updates in Flex Consumption

Azure Functions now supports rolling updates in the Flex Consumption plan, delivering zero-downtime deployments with a simple configuration change.  

Instead of forcefully restarting all instances during code or configuration updates, the platform gracefully replaces live instances by draining batches every few seconds while dynamically scaling out the latest version to meet demand. This approach ensures uninterrupted execution and resilient throughput across HTTP, non-HTTP, and Durable workloads—even during intensive scale-out scenarios.  

How to enable: 

1. Update your ARM/Bicep template with `”properties.functionAppConfig.siteUpdateStrategy.type”` set to `“RollingUpdate”` 

2. For Durable Functions, configure an orchestration match strategy (see guidance). 

Known limitations: 

• Scale-out issues may occur with low HTTP concurrency; recommended value is 16. 

• Real-time rollout monitoring is not supported; allow up to two minutes for completion. 

• No automatic rollback; intervene by redeploying the last healthy version. 

• Internal details such as batch size and drain intervals are not configurable and are subject to change. 

Learn more.