Working with Helm Charts

1. Installing Helm CLI

Platform	Installation Method	Command	Notes
Linux (x86_64)	Package Manager	`curl -fsSL https://raw.githubusercontent.com/helm/helm/main/scripts/get-helm-3 \| bash`	Installs latest stable version
macOS	Homebrew	`brew install helm`	Latest stable version from Homebrew
Windows	Chocolatey	`choco install kubernetes-helm`	Installs Helm via Chocolatey package manager
Windows	Manual Download	`curl -LO https://get.helm.sh/helm-v3.15.0-windows-amd64.zip`	Download and extract manually from Helm releases page
All Platforms	Binary Release	`curl -LO https://get.helm.sh/helm-v3.15.0-linux-amd64.tar.gz`	Download tarball and extract helm binary

Example: Verify Installation

helm version

Note: Helm requires kubectl to be installed and configured for cluster access.

2. Adding Helm Repositories

Command	Description	Options	Example
helm repo add	Add a new Helm repository	`--ca-file`, `--cert-file`, `--key-file`, `--username`, `--password`	`helm repo add stable https://charts.helm.sh/stable`

Note: The stable repository is deprecated as of Helm 3.12.0 and should not be used for new installations.

Warning: Adding repositories from untrusted sources can introduce security vulnerabilities.

Repository Management

Use helm repo add to register a new repository
Repositories are stored in $HOME/.helm/repository (Helm v2) or $HOME/.config/helm/repositories.yaml (Helm v3)
Use helm repo list to view registered repositories

3. Updating Helm Repositories

Command	Description	Notes
helm repo update	Updates the list of charts from all configured repositories	Fetches latest chart metadata and updates local cache
helm repo update <repo-name>	Updates a specific repository by name	Useful for updating only one repository when multiple exist

Example: Update all repositories

helm repo update

Example: Update specific repository

helm repo update my-repo

Note: The helm repo update command refreshes the local cache of chart information from remote repositories. It does not install or upgrade charts, but ensures that the local Helm client has the most recent chart metadata.

4. Searching Helm Charts

Command	Description	Flags
helm search repo	Search for charts in the configured repositories	`--devel` to include development charts `--regexp REGEXP` to filter by regex `--version VERSION` to specify version
helm search hub	Search for charts in Artifact Hub	`--endpoint ENDPOINT` to specify custom endpoint `--filter FILTER` to filter results by name or description `--limit LIMIT` to limit number of results

Example: Search for charts in a repository

helm search repo nginx

Example: Search for charts in Artifact Hub

helm search hub nginx

5. Installing Helm Chart

Option	Values	Description
--set	`key=value`	Set values on the command line (can be used multiple times)
--values	`values.yaml`	Specify values in a YAML file or URL
--namespace	`my-namespace`	Namespace to install the release into
--create-namespace	`true`	Create the namespace if it does not exist
--wait	`true`	Wait for all resources to be ready before marking the release as successful
--timeout	`300s`	Time to wait for any individual Kubernetes operation (default 5m0s)

Example: Installing a Helm Chart

helm install my-release stable/nginx-ingress \
  --set controller.service.type=LoadBalancer \
  --namespace production \
  --create-namespace \
  --wait

Note: The helm install command creates a new release. If you want to upgrade an existing release, use helm upgrade.

Warning: Ensure that the namespace exists or use --create-namespace to avoid errors during installation.

6. Upgrading Helm Release

Command	Description	Options
helm upgrade	Upgrades a release to a new version of the chart	`-i, --install` - Install the release if not already installed `--set` - Set values on the command line `--values, -f` - Specify values in a YAML file or string

Example: Upgrading a Release

helm upgrade my-release ./my-chart

Example: Upgrading with Values File

helm upgrade my-release ./my-chart -f values.yaml

Example: Upgrading with Set Values

helm upgrade my-release ./my-chart --set image.tag=v2.0

Note: If the release is not installed, use helm install instead of helm upgrade.

Warning: Ensure that the new chart version is compatible with the existing release to avoid unexpected behavior.

7. Rolling Back Release

Command	Description	Notes
helm rollback <release-name> [<revision>]	Rollback a release to a previous revision	Reinstalls the specified release at a given revision

Example: Rolling Back to Previous Revision

helm rollback my-app 3

Example: Rolling Back to Last Successful Revision

helm rollback my-app

Note: If no revision is specified, Helm rolls back to the previous release.

Warning: Rolling back may cause data loss if the previous revision had different configurations or resources.

Flag	Description	Default
--debug	Enable debug output	false
--dry-run	Simulate a rollback without making changes	false
--recreate-pods	Recreate pods for resources that support it	false
--timeout	Time to wait for any individual Kubernetes operation	5m0s
--wait	Wait for resources to be ready after rollback	false

8. Listing Helm Releases

Command	Description	Flags
helm list	List all Helm releases in the current namespace	`-n, --namespace` to specify a namespace `-q, --short` for concise output
helm list --all-namespaces	List all Helm releases across all namespaces	`--all-namespaces` or `-A`
helm list --deployed	List only deployed releases	`--deployed`
helm list --suppressed	List only suppressed releases	`--suppressed`
helm list --pending	List only pending releases	`--pending`
helm list --failed	List only failed releases	`--failed`

Example: Listing Helm Releases in a Specific Namespace

helm list -n production

Example: Listing All Helm Releases Across Namespaces

helm list --all-namespaces

Note: By default, helm list shows only deployed releases. Use flags like --failed, --pending, or --suppressed to view other release statuses.

9. Viewing Release Values

Command	Description	Example
helm get values	Fetches the values of a release	`helm get values my-release`
helm get values -a	Fetches all values including defaults	`helm get values -a my-release`
helm get values -o yaml	Outputs values in YAML format	`helm get values -o yaml my-release`

Example: Fetching Release Values

helm get values my-release
# Output:
# database.host: mysql.example.com
# database.port: 3306
# database.name: myapp

Example: Fetching All Values Including Defaults

helm get values -a my-release
# Output:
# database.host: mysql.example.com
# database.port: 3306
# database.name: myapp
# database.username: admin
# database.password: secret

10. Uninstalling Helm Release

Option	Values	Description
helm uninstall	`RELEASE_NAME`	Uninstalls a Helm release by its name
--namespace	`_NAMESPACE_`	Specifies the namespace where the release is installed
--dry-run	`true`	Simulates the uninstallation without making changes
--keep-history	`true`	Retains release history after uninstallation

Example: Uninstalling a Helm Release

helm uninstall my-release --namespace my-namespace

Example: Dry Run Uninstall

helm uninstall my-release --dry-run --namespace my-namespace

Note: By default, Helm retains the release history. Use --keep-history=false to delete history as well.

11. Creating Custom Chart

Example: Basic Chart Structure

helm create my-app

File/Directory	Description	Notes
Chart.yaml	Chart metadata	Required file with name, version, appVersion, etc.
values.yaml	Default values for templates	Overrideable by users or CI/CD
templates/	Template files	Contains Kubernetes manifests
templates/deployment.yaml	Deployment manifest	Example template using values
templates/service.yaml	Service manifest	Exposes the deployment
templates/_helpers.tpl	Helper templates	Reusable template snippets

Example: Deployment Template

apiVersion: apps/v1
kind: Deployment
metadata:
  name: {{ include "my-app.fullname" . }}
spec:
  replicas: {{ .Values.replicaCount }}
  selector:
    matchLabels:
      {{- include "my-app.labels" . | nindent 8 }}
  template:
    metadata:
      {{- with .Values.podAnnotations }}
      annotations:
        {{- toYaml . | nindent 8 }}
      {{- end }}
      labels:
        {{- include "my-app.labels" . | nindent 8 }}
    spec:
      containers:
        - name: {{ .Chart.Name }}
          image: "{{ .Values.image.repository }}:{{ .Values.image.tag | default .Chart.AppVersion }}"
          ports:
            - containerPort: {{ .Values.service.port }}

Example: Values Override

replicaCount: 3
image:
  repository: nginx
  tag: "1.21"
service:
  port: 80

Note: Use helm template to preview chart before installing.

Warning: Avoid hardcoding values in templates; use .Values instead.

12. Using Helm Templating

Feature	Description	Usage
.Release.Name	Release name of the Helm release	`{{ .Release.Name }}`
.Values	Values provided to the chart	`{{ .Values.database.port }}`
.Chart	Chart metadata (name, version)	`{{ .Chart.Name }}-{{ .Chart.Version }}`
.Files	Access to files in the chart	`{{ .Files.Get "config.yaml" }}`

Example: Using .Values in a Deployment

apiVersion: apps/v1
kind: Deployment
metadata:
  name: {{ include "myapp.fullname" . }}
spec:
  replicas: {{ .Values.replicaCount }}
  selector:
    matchLabels:
      {{- include "myapp.selectorLabels" . | nindent 6 }}
  template:
    metadata:
      {{- with .Values.podAnnotations }}
      annotations:
        {{- toYaml . | nindent 8 }}
      {{- end }}
    spec:
      containers:
        - name: {{ .Chart.Name }}
          image: "{{ .Values.image.repository }}:{{ .Values.image.tag }}"
          ports:
            - containerPort: {{ .Values.service.port }}

Example: Conditional Template with .Values

{{- if .Values.service.enabled }}
apiVersion: v1
kind: Service
metadata:
  name: {{ include "myapp.fullname" . }}
spec:
  type: {{ .Values.service.type }}
  ports:
    - port: {{ .Values.service.port }}
      targetPort: {{ .Values.service.targetPort }}
{{- end }}

Note: Helm templates use Go template syntax. Always test your templates with helm template before deploying.

Warning: Avoid complex logic in templates. Keep templates simple and readable.