KEDA Event-Driven Autoscaling Cheat Sheet

Updated 2026-05-22

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KEDA (Kubernetes Event-Driven Autoscaling) is a CNCF graduated project that extends Kubernetes with event-driven scaling capabilities, acting as both a Kubernetes Operator and a custom metrics adapter. While the built-in HPA can only scale on CPU and memory, KEDA connects workloads to 79+ external event sources — message queues, streaming platforms, databases, and custom metrics APIs — and uniquely enables scale-to-zero, making it indispensable for cloud-native architectures where idle resources carry cost. The crucial mental model is that KEDA controls the 0↔1 transition directly, then hands off 1↔N scaling to a managed HPA; understanding where each component takes responsibility explains virtually every behavior practitioners encounter.

What This Cheat Sheet Covers

This topic spans 16 focused tables and 152 indexed concepts. Below is a complete table-by-table outline of this topic, spanning foundational concepts through advanced details.

Table 1: KEDA Architecture and Core ComponentsTable 2: ScaledObject Core Specification FieldsTable 3: ScaledJob Core Specification FieldsTable 4: Scale-to-Zero and Activation BehaviorTable 5: Scaler Catalog — Message Queues and StreamingTable 6: Scaler Catalog — Cloud, Observability, and DatabaseTable 7: TriggerAuthentication and Credential ManagementTable 8: Scaling Behavior Tuning — HPA and Advanced ConfigTable 9: Fallback Configuration and Failure ModesTable 10: Multi-Trigger Scenarios and Trigger CompositionTable 11: KEDA HTTP Add-on — HTTP Scale-to-ZeroTable 12: External and Custom Scalers (gRPC Interface)Table 13: Deployment, Operations, and ObservabilityTable 14: Key Scaler Parameters — Kafka, SQS, Cron Deep DiveTable 15: Common Pitfalls, Debugging, and Best PracticesTable 16: KEDA Integration Patterns — Karpenter, AI, and Multi-Tenant

Table 1: KEDA Architecture and Core Components

KEDA is composed of three distinct Kubernetes deployments plus a set of CRDs; each component has a clearly bounded responsibility. Understanding which process does what is the foundation for diagnosing any scaling issue.

Component	Example	Description
KEDA Operator	`kubectl get deploy -n keda keda-operator`	Watches ScaledObject/ScaledJob CRDs, activates/deactivates workloads (0↔1), and creates/manages the underlying HPA.
Metrics Server (Adapter)	`kubectl get deploy -n keda keda-metrics-apiserver`	• Implements the Kubernetes External Metrics API • serves scaler metric values to the HPA so HPA can drive 1↔N scaling
Admission Webhooks	`kubectl get deploy -n keda keda-admission-webhooks`	Validates ScaledObject/ScaledJob manifests at apply time to catch misconfigurations before they affect production.
ScaledObject CRD	`apiVersion: keda.sh/v1alpha1` `kind: ScaledObject`	Custom resource linking a Deployment/StatefulSet/Custom Resource to one or more event-source triggers with full scaling config.
ScaledJob CRD	`apiVersion: keda.sh/v1alpha1` `kind: ScaledJob`	Custom resource that spawns a new Kubernetes Job per event batch rather than scaling a long-running Deployment.

Table 1: KEDA Architecture and Core Components

Component	Example	Description
KEDA Operator	`kubectl get deploy -n keda keda-operator`	Watches ScaledObject/ScaledJob CRDs, activates/deactivates workloads (0↔1), and creates/manages the underlying HPA.
Metrics Server (Adapter)	`kubectl get deploy -n keda keda-metrics-apiserver`	• Implements the Kubernetes External Metrics API • serves scaler metric values to the HPA so HPA can drive 1↔N scaling
Admission Webhooks	`kubectl get deploy -n keda keda-admission-webhooks`	Validates ScaledObject/ScaledJob manifests at apply time to catch misconfigurations before they affect production.
ScaledObject CRD	`apiVersion: keda.sh/v1alpha1` `kind: ScaledObject`	Custom resource linking a Deployment/StatefulSet/Custom Resource to one or more event-source triggers with full scaling config.
ScaledJob CRD	`apiVersion: keda.sh/v1alpha1` `kind: ScaledJob`	Custom resource that spawns a new Kubernetes Job per event batch rather than scaling a long-running Deployment.