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Schedule Kubernetes Horizontal Pod Autoscaling (HPA) using KEDA’s Cron trigger to automatically adjust replica counts at specific times. This approach helps you:
  • Handle predictable traffic spikes (e.g., morning rush).
  • Save resources by scaling down during idle periods.
  • Automate capacity management for promotional events.

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How KEDA Cron Triggers Work

A Cron trigger in KEDA allows you to:
  1. Specify an IANA timezone for scheduling.
  2. Define start and end times with standard CRON expressions.
  3. Set a desiredReplicas count for the active window.
The image is a diagram illustrating "KEDA Cron" with icons representing Cron, KEDA, a database, and a time zone.
When the clock matches your start expression, KEDA scales the target Deployment up to desiredReplicas. After the end expression, it scales back down (respecting your minReplicaCount).

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Common Use Cases

ScenarioScheduleBenefit
Daily Traffic Spike0 6 * * * – 0 8 * * *Pre-warm pods for morning users
Promotional Campaign0 12 * * 5 – 0 18 * * 5Extra capacity during Friday sales
Off-Hours Optimization0 20 * * * – 0 6 * * *Scale down to save costs overnight
The image outlines the concept of KEDA Cron for predetermined scaling, detailing the requirement, solution, outcome, and a real-life use case for handling traffic spikes.

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When to Use Time-Based Scaling

  • Predictable Load Windows: Morning routines, lunch peaks, end-of-business-day reporting.
  • Short-Lived Events: Flash sales, marketing campaigns.
  • Cost Management: Turn off extra capacity when it isn’t needed.

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24-Hour Scaling Graph

The image is a graph showing KEDA Cron's predetermined scaling of workload instances over a 24-hour period, with increased activity between 6:00 am and 6:00 pm.
This graph illustrates:
  • Baseline: Default replica count until 06:00.
  • Scale-Up: Jump to desiredReplicas during the 6:00–20:00 window.
  • Scale-Down: Return to baseline after 20:00.

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Defining the Cron Trigger in KEDA

Add a Cron trigger under spec.triggers in your ScaledObject manifest: 
triggers:
  - type: cron
    metadata:
      timezone: Asia/Kolkata       # IANA Time Zone Database
      start: "0 6 * * *"           # 06:00 daily
      end: "0 20 * * *"            # 20:00 daily
      desiredReplicas: "10"        # Target replicas during active window
FieldRangeDescription
minute0–59Minute of the hour
hour0–23Hour of the day
day-of-month1–31Date
month1–12Month number
day-of-week0–6Weekday (Sun=0)
Make sure to use the exact IANA timezone string (e.g., America/New_York). An incorrect value can prevent your schedule from triggering.

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Complete ScaledObject Example

Below is a full example combining the Cron trigger with a Deployment target. It scales my-deployment up to 10 replicas between 06:00 and 20:00 Asia/Kolkata time, then scales down to zero after a 5 minute cooldown. 
apiVersion: keda.sh/v1alpha1
kind: ScaledObject
metadata:
  name: cron-scaledobject
  namespace: default
spec:
  scaleTargetRef:
    name: my-deployment
  minReplicaCount: 0
  cooldownPeriod: 300            # 5 minutes before scaling down
  triggers:
    - type: cron
      metadata:
        timezone: Asia/Kolkata
        start: "0 6 * * *"
        end: "0 20 * * *"
        desiredReplicas: "10"
With this configuration, KEDA automatically aligns your application’s capacity to match scheduled demand patterns, improving performance and cost efficiency.

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