Container Apps KEDA Scaling with Service Bus Queue Workers

Modern event-driven architectures often rely on message queues to decouple producers from consumers, but a static pool of worker containers wastes money during quiet periods and buckles under sudden traffic spikes. KEDA (Kubernetes Event-driven Autoscaling) solves this by watching external event sources - such as Azure Service Bus queue depth - and dynamically adjusting replica counts, including scaling all the way down to zero when there is no work to process.

Azure Container Apps has KEDA built in, so you can attach a scale rule to any container app without managing a Kubernetes cluster yourself. In this lab, you will deploy a queue-worker container to a Container Apps environment, configure a KEDA scale rule that targets the Service Bus queue's messageCount metric, flood the queue with over 200 messages to trigger a burst scale-out from zero to five replicas, and then observe the workers drain the queue and scale back to zero.

Objectives

By completing this intermediate lab, you will be able to:

• Build and push a queue-worker container image to Azure Container Registry
• Deploy a Container App with a KEDA scale rule targeting Service Bus queue messageCount
• Generate a burst of 200+ messages on the Service Bus queue using a sender script
• Monitor replica scale-out from zero to five in real time using Azure CLI and the portal
• Observe scale-to-zero behavior after the queue is fully drained

Who is this lab for?

This lab is designed for:

• Cloud engineers learning event-driven autoscaling patterns on Azure
• Developers building asynchronous workload processors with Container Apps
• DevOps engineers implementing scale-to-zero architectures for cost optimization