Optimizing Chart Performance

1. Minimizing Template Complexity

Anti-pattern	Fix
Deeply nested conditionals	Extract to named template
Repeated `include`	Cache result in variable
Complex inline expressions	Compute once into variable

2. Caching Template Results

Example: Cache expensive include

{{- $labels := include "myapp.labels" . -}}
metadata:
  labels: {{- $labels | nindent 4 }}
---
spec:
  template:
    metadata:
      labels: {{- $labels | nindent 8 }}

3. Reducing Value Lookups

Example: Bind once with `with`

{{- with .Values.resources }}
resources:
  requests: { cpu: {{ .cpuRequest }}, memory: {{ .memRequest }} }
  limits:   { cpu: {{ .cpuLimit }},   memory: {{ .memLimit }} }
{{- end }}

4. Optimizing Loop Iterations

Practice	Why
Filter before range	Reduce iteration count
Hoist invariants	Compute outside `range`
Avoid nested ranges	O(n²) renders are slow

5. Using Conditional Rendering

Example: Skip unused blocks

{{- if .Values.metrics.enabled }}
{{- include "myapp.metrics-service" . }}
{{- include "myapp.servicemonitor" . }}
{{- end }}

6. Minimizing File Reads

Practice	Detail
Cache `.Files.Get`	Read once into variable, reuse
Use `Glob`	Iterate matched files instead of listing manually
Avoid huge files	Move large blobs to ConfigMap mounted at runtime

7. Reducing Chart Size

Action	Effect
Add `.helmignore`	Exclude tests, docs, CI files from package
Remove unused subcharts	Use `condition:`
Minify embedded files	Strip whitespace from JSON/YAML blobs

8. Optimizing Dependencies

Use library charts for shared logic Pin subchart versions to skip resolution Disable unused subcharts via condition Commit Chart.lock for fast CI builds Use helm dependency build in CI (lock-driven)

9. Using Lazy Evaluation

Example: Short-circuit expensive checks

{{- if and .Values.lookup.enabled (eq .Release.IsInstall false) }}
{{- $existing := lookup "v1" "Secret" .Release.Namespace "db-creds" -}}
{{- end }}

10. Profiling Chart Rendering

Example: Measure render time

time helm template ./chart -f values-prod.yaml > /dev/null
# Compare branches
hyperfine 'helm template ./chart-old' 'helm template ./chart-new'

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Kubernetes