7.4Template Rendering and Validation

Rendering templates without deploying is the most important testing step. It catches issues that lint cannot detect because lint does not evaluate template logic.

# Render templates with default values
helm template myapp ./charts/myapp/

# Render with production values
helm template myapp ./charts/myapp/ \
  --values values-production.yaml

# Pipe rendered output to kubeconform for K8s schema validation
helm template myapp ./charts/myapp/ \
  --values values-production.yaml | kubeconform -strict

# Test with multiple value files
helm template myapp ./charts/myapp/ \
  --values values-production.yaml \
  --values values-us-east-1.yaml | kubeconform -strict

# Render with value overrides to test specific scenarios
helm template myapp ./charts/myapp/ \
  --set replicas=1 \
  --set image.tag=latest \
  --set ingress.enabled=true | kubeconform -strict

Testing All Value Combinations

#!/bin/bash
# scripts/test-helm-values.sh
# Test chart rendering with all supported value files

CHART_DIR="./charts/myapp"
FAILURES=0

# Test each environment's values
for values_file in values-*.yaml; do
    echo "Testing with $values_file..."
    if ! helm template myapp "$CHART_DIR" --values "$values_file" | kubeconform -strict; then
        echo "FAIL: $values_file produces invalid manifests"
        FAILURES=$((FAILURES + 1))
    fi
done

# Test with minimal values (defaults only)
echo "Testing with defaults only..."
if ! helm template myapp "$CHART_DIR" | kubeconform -strict; then
    echo "FAIL: Default values produce invalid manifests"
    FAILURES=$((FAILURES + 1))
fi

if [ $FAILURES -gt 0 ]; then
    echo "$FAILURES value combinations failed"
    exit 1
fi
echo "All value combinations passed"