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Helm Cheat Sheet

Name origin: Helm means "ship's steering wheel" — fitting the nautical Kubernetes naming theme (kubernetes = Greek for "helmsman"). Helm is the "package manager for Kubernetes," analogous to apt/yum for Linux.

Core Commands

# Search for charts
helm search repo nginx
helm search hub prometheus          # Artifact Hub

# Install
helm install myapp ./chart/         # From local directory
helm install myapp repo/chart       # From repo
helm install myapp repo/chart -f values-prod.yaml -n production

# Upgrade
helm upgrade myapp repo/chart -f values.yaml
helm upgrade --install myapp repo/chart  # Install if not exists

# Rollback
helm rollback myapp 1               # Rollback to revision 1
helm rollback myapp 0               # Rollback to previous
# Gotcha: rollback creates a NEW revision (not a revert). Revision history grows.

# Uninstall
helm uninstall myapp -n production

# Status
helm list -A                         # All releases, all namespaces
helm status myapp -n production
helm history myapp -n production     # Revision history

Gotcha: helm upgrade without --reuse-values resets all values to chart defaults, then applies only the values you explicitly pass. This silently drops custom values from previous installs. Always use helm upgrade -f values.yaml with your full values file, or use --reuse-values to keep previous values (but beware: --reuse-values does not pick up new chart default changes).

Debugging

# Render templates without installing
helm template myapp ./chart/ -f values.yaml

# Dry-run against cluster (validates API compatibility)
helm install myapp ./chart/ --dry-run --debug

# Show computed values
helm get values myapp -n production
helm get values myapp -n production --all   # Including defaults

# Show generated manifests
helm get manifest myapp -n production

# Lint chart
helm lint ./chart/

Chart Structure

mychart/
├── Chart.yaml          # Name, version, dependencies
├── values.yaml         # Default values
├── templates/
│   ├── deployment.yaml
│   ├── service.yaml
│   ├── ingress.yaml
│   ├── _helpers.tpl    # Template helpers (named templates)
│   ├── NOTES.txt       # Post-install message
│   └── tests/
│       └── test-connection.yaml
├── charts/             # Dependency charts
└── .helmignore

Values & Templating

# values.yaml
replicaCount: 3
image:
  repository: myapp
  tag: "v1.0"
  pullPolicy: IfNotPresent

# In templates:
replicas: {{ .Values.replicaCount }}
image: "{{ .Values.image.repository }}:{{ .Values.image.tag }}"

# Conditionals
{{- if .Values.ingress.enabled }}
apiVersion: networking.k8s.io/v1
kind: Ingress
...
{{- end }}

# Loops
{{- range .Values.extraEnv }}
- name: {{ .name }}
  value: {{ .value | quote }}
{{- end }}

# Default values
{{ .Values.resources.limits.cpu | default "500m" }}

Dependency Management

# Chart.yaml
dependencies:
- name: postgresql
  version: "12.x.x"
  repository: https://charts.bitnami.com/bitnami
  condition: postgresql.enabled

helm dependency update ./chart/
helm dependency build ./chart/

Repository Management

helm repo add bitnami https://charts.bitnami.com/bitnami
helm repo add prometheus https://prometheus-community.github.io/helm-charts
helm repo update
helm repo list

Common Flags

Flag Purpose
-f values.yaml Override values file
--set key=val Override single value
--set-string key=val Force string type
-n namespace Target namespace
--create-namespace Create namespace if needed
--wait Wait until all resources are ready
--timeout 5m Timeout for --wait
--atomic Rollback on failure

Troubleshooting

Problem Command
See what changed helm diff upgrade myapp ./chart/ (helm-diff plugin)
Stuck in pending helm rollback myapp 0
Bad values helm get values myapp
Template error helm template myapp ./chart/ --debug
Release not found helm list -A --all (includes failed/uninstalled)