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Helm

Helm is the package manager for Kubernetes. A chart is a package (like an npm package but for K8s manifests).

Concepts​

TermWhat it is
ChartA package of Kubernetes manifests
ReleaseA deployed instance of a chart
RepositoryA collection of charts (like a registry)
ValuesConfiguration you pass to customise a chart

Repositories​

helm repo add bitnami https://charts.bitnami.com/bitnami
helm repo add stable https://charts.helm.sh/stable
helm repo update                    # refresh all repos
helm repo list                      # show added repos
helm repo remove <name>
helm search repo nginx              # search in added repos
helm search hub nginx               # search Artifact Hub (public)

Install​

helm install <release-name> <chart>
helm install my-nginx bitnami/nginx
helm install my-nginx bitnami/nginx -n staging          # specific namespace
helm install my-nginx bitnami/nginx --create-namespace  # create ns if missing
helm install my-nginx ./my-chart                        # local chart

Pass custom values:

helm install my-nginx bitnami/nginx \
  --set service.type=ClusterIP \
  --set replicaCount=2

Or use a values file:

helm install my-nginx bitnami/nginx -f values.yaml

Upgrade​

helm upgrade <release-name> <chart>
helm upgrade my-nginx bitnami/nginx
helm upgrade my-nginx bitnami/nginx -f values.yaml
helm upgrade my-nginx bitnami/nginx --set replicaCount=3

# Install if not exists, upgrade if it does
helm upgrade --install my-nginx bitnami/nginx -f values.yaml

List Releases​

helm list
helm list -n staging
helm list -A                        # all namespaces

Status & Info​

helm status my-nginx
helm get values my-nginx            # values used for this release
helm get values my-nginx --all      # all values including defaults
helm get manifest my-nginx          # rendered K8s manifests

Rollback​

helm history my-nginx               # show revision history
helm rollback my-nginx              # roll back to previous revision
helm rollback my-nginx 2            # roll back to revision 2

Uninstall​

helm uninstall my-nginx
helm uninstall my-nginx -n staging

Template (Dry Run / Debug)​

Render the chart to YAML without installing — useful to see what will be applied:

helm template my-nginx bitnami/nginx -f values.yaml
helm template my-nginx bitnami/nginx -f values.yaml > rendered.yaml

Lint a chart for errors:

helm lint ./my-chart

Creating a Chart​

helm create my-chart        # scaffold a new chart

Structure:

my-chart/
├── Chart.yaml          # metadata (name, version, description)
├── values.yaml         # default values
└── templates/          # K8s manifest templates
    ├── deployment.yaml
    ├── service.yaml
    └── ingress.yaml

Reference values in templates with {{ .Values.replicaCount }}.

values.yaml Tips​

replicaCount: 2

image:
  repository: nginx
  tag: "1.25"
  pullPolicy: IfNotPresent

service:
  type: ClusterIP
  port: 80

resources:
  limits:
    cpu: 500m
    memory: 256Mi
  requests:
    cpu: 100m
    memory: 128Mi

Override at install/upgrade time:

helm upgrade my-app ./my-chart \
  --set image.tag=1.26 \
  --set replicaCount=3

Helm + kubectl Together​

# See what Helm deployed
helm get manifest my-nginx | kubectl apply --dry-run=client -f -

# Debug a failing release
helm status my-nginx
kubectl get pods -l app.kubernetes.io/instance=my-nginx
kubectl logs -l app.kubernetes.io/instance=my-nginx