K8s Autoscaling

Kubernetes Autoscaling

Comprehensive autoscaling using HPA, VPA, and KEDA with kubectl-mcp-server tools.

When to Apply

Use this skill when:

• User mentions: "HPA", "VPA", "KEDA", "autoscale", "scale to zero"
• Operations: configuring autoscaling, checking scaling status
• Keywords: "scale automatically", "event-driven", "right-size"

Priority Rules

Quick Reference

HPA (Horizontal Pod Autoscaler)

Basic CPU-based scaling:

apiVersion: autoscaling/v2
kind: HorizontalPodAutoscaler
metadata:
  name: my-app-hpa
spec:
  scaleTargetRef:
    apiVersion: apps/v1
    kind: Deployment
    name: my-app
  minReplicas: 2
  maxReplicas: 10
  metrics:
  - type: Resource
    resource:
      name: cpu
      target:
        type: Utilization
        averageUtilization: 70

Apply and verify:

kubectl_apply(hpa_yaml, namespace)
get_hpa(namespace)

VPA (Vertical Pod Autoscaler)

Right-size resource requests:

apiVersion: autoscaling.k8s.io/v1
kind: VerticalPodAutoscaler
metadata:
  name: my-app-vpa
spec:
  targetRef:
    apiVersion: apps/v1
    kind: Deployment
    name: my-app
  updatePolicy:
    updateMode: "Auto"

KEDA (Event-Driven Autoscaling)

Detect KEDA Installation

keda_detect_tool()

List ScaledObjects

keda_scaledobjects_list_tool(namespace)
keda_scaledobject_get_tool(name, namespace)

List ScaledJobs

keda_scaledjobs_list_tool(namespace)

Trigger Authentication

keda_triggerauths_list_tool(namespace)
keda_triggerauth_get_tool(name, namespace)

KEDA-Managed HPAs

keda_hpa_list_tool(namespace)

See KEDA-TRIGGERS.md for trigger configurations.

Common KEDA Triggers

Queue-Based Scaling (AWS SQS)

apiVersion: keda.sh/v1alpha1
kind: ScaledObject
metadata:
  name: sqs-scaler
spec:
  scaleTargetRef:
    name: queue-processor
  minReplicaCount: 0
  maxReplicaCount: 100
  triggers:
  - type: aws-sqs-queue
    metadata:
      queueURL: https://sqs.region.amazonaws.com/...
      queueLength: "5"

Cron-Based Scaling

triggers:
- type: cron
  metadata:
    timezone: America/New_York
    start: 0 8 * * 1-5
    end: 0 18 * * 1-5
    desiredReplicas: "10"

Prometheus Metrics

triggers:
- type: prometheus
  metadata:
    serverAddress: http://prometheus:9090
    metricName: http_requests_total
    query: sum(rate(http_requests_total{app="myapp"}[2m]))
    threshold: "100"

Scaling Strategies

Cost-Optimized Autoscaling

Scale to Zero with KEDA

Reduce costs for idle workloads:

keda_scaledobjects_list_tool(namespace)

Right-Size with VPA

Get recommendations and apply:

get_resource_recommendations(namespace)

Troubleshooting

HPA Not Scaling

get_hpa(namespace)
get_pod_metrics(name, namespace)
describe_pod(name, namespace)

KEDA Not Triggering

keda_scaledobject_get_tool(name, namespace)
get_events(namespace)

Common Issues

Best Practices

1. Always Set Resource Requests - HPA requires requests to calculate utilization 2. Use Multiple Metrics - Combine CPU + custom metrics for accuracy 3. Stabilization Windows - Prevent flapping with scaleDown stabilization 4. Scale to Zero Carefully - Consider cold start time

Related Skills

• k8s-cost - Cost optimization
• k8s-troubleshoot - Debug scaling issues

KEDA Trigger Reference

Common KEDA trigger configurations.

Queue-Based Triggers

AWS SQS

apiVersion: keda.sh/v1alpha1
kind: ScaledObject
metadata:
  name: sqs-scaler
spec:
  scaleTargetRef:
    name: queue-processor
  minReplicaCount: 0
  maxReplicaCount: 100
  triggers:
  - type: aws-sqs-queue
    metadata:
      queueURL: https://sqs.region.amazonaws.com/123456789/my-queue
      queueLength: "5"  # Scale when > 5 messages per pod
      awsRegion: us-east-1
    authenticationRef:
      name: aws-credentials

RabbitMQ

triggers:
- type: rabbitmq
  metadata:
    protocol: amqp
    queueName: my-queue
    mode: QueueLength
    value: "10"
    host: amqp://user:pass@rabbitmq.default.svc:5672

Azure Service Bus

triggers:
- type: azure-servicebus
  metadata:
    queueName: my-queue
    messageCount: "5"
  authenticationRef:
    name: azure-sb-auth

Kafka

triggers:
- type: kafka
  metadata:
    bootstrapServers: kafka:9092
    consumerGroup: my-consumer
    topic: my-topic
    lagThreshold: "100"

Metric-Based Triggers

Prometheus

triggers:
- type: prometheus
  metadata:
    serverAddress: http://prometheus:9090
    metricName: http_requests_total
    query: sum(rate(http_requests_total{app="myapp"}[2m]))
    threshold: "100"

Datadog

triggers:
- type: datadog
  metadata:
    query: avg:system.cpu.user{app:myapp}
    queryValue: "80"
    type: global
  authenticationRef:
    name: datadog-auth

Schedule-Based Triggers

Cron

triggers:
- type: cron
  metadata:
    timezone: America/New_York
    start: 0 8 * * 1-5   # 8 AM Mon-Fri
    end: 0 18 * * 1-5    # 6 PM Mon-Fri
    desiredReplicas: "10"

Multiple Schedules

triggers:
# Morning peak
- type: cron
  metadata:
    timezone: UTC
    start: 0 8 * * *
    end: 0 10 * * *
    desiredReplicas: "20"
# Afternoon peak
- type: cron
  metadata:
    timezone: UTC
    start: 0 14 * * *
    end: 0 16 * * *
    desiredReplicas: "15"

HTTP-Based Triggers

HTTP Request Count

triggers:
- type: prometheus
  metadata:
    serverAddress: http://prometheus:9090
    query: sum(rate(nginx_http_requests_total[1m]))
    threshold: "1000"

Database Triggers

PostgreSQL

triggers:
- type: postgresql
  metadata:
    connectionFromEnv: PG_CONNECTION
    query: "SELECT COUNT(*) FROM pending_jobs WHERE status = 'pending'"
    targetQueryValue: "10"

MySQL

triggers:
- type: mysql
  metadata:
    connectionStringFromEnv: MYSQL_CONNECTION
    query: "SELECT COUNT(*) FROM work_queue"
    queryValue: "5"

Authentication

TriggerAuthentication

apiVersion: keda.sh/v1alpha1
kind: TriggerAuthentication
metadata:
  name: aws-credentials
spec:
  secretTargetRef:
  - parameter: awsAccessKeyID
    name: aws-secrets
    key: AWS_ACCESS_KEY_ID
  - parameter: awsSecretAccessKey
    name: aws-secrets
    key: AWS_SECRET_ACCESS_KEY

ClusterTriggerAuthentication

For cluster-wide auth:

apiVersion: keda.sh/v1alpha1
kind: ClusterTriggerAuthentication
metadata:
  name: aws-credentials-cluster
spec:
  secretTargetRef:
  - parameter: awsAccessKeyID
    name: aws-secrets
    key: AWS_ACCESS_KEY_ID
    namespace: keda

Advanced Configuration

Activation Threshold

Don't scale from 0 until threshold met:

spec:
  minReplicaCount: 0
  advanced:
    horizontalPodAutoscalerConfig:
      behavior:
        scaleDown:
          stabilizationWindowSeconds: 300
  triggers:
  - type: prometheus
    metadata:
      threshold: "100"
    metricType: AverageValue

Cool Down Period

spec:
  cooldownPeriod: 300  # Wait 5 min before scaling down

Polling Interval

spec:
  pollingInterval: 30  # Check every 30 seconds

MCP Commands

# List ScaledObjects
keda_scaledobjects_list_tool(namespace)

# Get ScaledObject details
keda_scaledobject_get_tool(name, namespace)

# List TriggerAuthentications
keda_triggerauths_list_tool(namespace)

# Get TriggerAuthentication
keda_triggerauth_get_tool(name, namespace)

# List KEDA-managed HPAs
keda_hpa_list_tool(namespace)

Troubleshooting

ScaledObject Not Scaling

keda_scaledobject_get_tool(name, namespace)
# Check status conditions
get_events(namespace)

Common Issues:

• Invalid trigger configuration
• Authentication failure
• Metric not found

Metric Query Issues

# For Prometheus, test query manually:
# curl prometheus:9090/api/v1/query?query=<your-query>