Azure availability zones are physically separate locations in each Azure region and are tolerant to local failures. For example, failures can range from software and hardware failures to events such as earthquakes, floods, and fires. These zones achieve tolerance through the redundancy and logical isolation of Azure services. To provide resiliency and distributed availability, at least three separate availability zones exist in all regions that enable these zones. For more information about availability zones, review Azure regions and availability zones - Microsoft Docs.

Soon, Azure Logic Apps will support availability zones for both Consumption and Standard logic apps. Both workflow executions and Azure Logic Apps plans will be distributed across three zones in any Azure region enabled with availability zones. This capability is a key requirement for enabling resilient architectures and providing high availability if datacenter failures happen in a region.

For Consumption logic apps, the multi-tenant Azure Logic Apps platform will handle zone distribution. After you opt in to enable availability zone support for any new Consumption logic apps that you create, workloads will be distributed across all three zones without any other setup. Eventually, availability Zone support will be automatically enabled for all existing Consumption logic apps without any other required setup.

For Standard logic apps, the single-tenant Azure Logic Apps platform will distribute and balance workloads across all three zones. If you set up zone redundancy, the platform will automatically spread Workflow Standard plan instances across all three zones in the selected Azure region. If you specify a capacity larger than three zones, and the number of plan instances is divisible by three, these instances are spread evenly. If the number isn’t divisible by three, the remainder that exceeds 3*N will be spread across the remaining one or two zones.

What do you need to prepare?

To support the new zones, we will add new inbound and outbound IP addresses for Azure Logic Apps. If you have firewall configurations that allow communication with these Azure Logic Apps IP addresses, you will have to add the new addresses, which will be described in the documentation, Limits and configuration reference for Azure Logic Apps.