KEDA External Scaler

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KEDA External Scaler

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Architecture Overview

1. Receiver: Implements the OTLP Receiver specification, running a gRPC server (default port 4317) that receives and processes incoming metrics.
2. In-Memory Metric Storage: A high-performance in-memory storage system that maintains recent metric measurements for each metric vector. Key features include:
   • Automatic cleanup of stale measurements
   • Label-based querying support
   • Optimized for real-time metric processing
3. External Scaler: Implements the KEDA External Scaler contract, running a gRPC server (default port 4318) that queries the metric storage and communicates with the KEDA operator.

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Installation

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Prerequisites

• Kubernetes cluster
• KEDA installed
• Helm 3.x

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Step 1: Install KEDA

helm repo add kedacore https://kedacore.github.io/charts
helm repo update
helm upgrade -i keda kedacore/keda --namespace keda --create-namespace

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Step 2: Configure Sawmills Collector with KEDA Scaler

managedChartsValues:
  sawmills-collector:
    # Enable KEDA-based autoscaling
    keda:
      enabled: true
      minReplicas: 1
      maxReplicas: 10
      pollingInterval: 30
      cooldownPeriod: 300
      scaling:
        external:
          enabled: true
          metricType: Value
          metadata:
            query: "histogram_quantile(0.95, sum(rate(http_server_duration_bucket[2m])) by (le))"
            targetValue: "2000"

    # Enable KEDA scaler component
    kedaScaler:
      enabled: true

Note: The chart derives the KEDA scaler service address from the rendered scaler service name and the Helm release namespace. Avoid hardcoding a namespace in scalerAddress, especially when deploying through an umbrella chart or using resourceBaseName.