Introduction to Helm

Helm is the package manager for Kubernetes, similar to how apt is for Ubuntu or pip for Python. It helps you manage Kubernetes applications through Helm Charts.

Core Concepts

  1. Charts: Helm packages that contain all the resource definitions necessary to run an application in Kubernetes
  2. Repositories: Places where charts are collected and shared
  3. Releases: Instances of charts running in a Kubernetes cluster

Helm vs. Kustomize

  • Helm: Template-based approach, package management, versioning
  • Kustomize: Overlay-based approach, native to kubectl, no templating

Basic Commands

Repository Management

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# Add repository
helm repo add bitnami https://charts.bitnami.com/bitnami

# Update repositories
helm repo update

# List repositories
helm repo list

# Remove repository
helm repo remove bitnami

# Search charts
helm search repo mysql
helm search hub wordpress

Chart Installation

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# Install a chart
helm install release-name chart-name
helm install my-mariadb bitnami/mariadb
helm install my-mariadb bitnami/mariadb --version 14.1.2

# Install with custom values
helm install my-mariadb bitnami/mariadb -f values.yaml
helm install my-mariadb bitnami/mariadb --set param=value

# Install from OCI registry
helm install my-release oci://registry-1.docker.io/bitnamicharts/mariadb

Release Management

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# List releases
helm list
helm ls -A  # All namespaces

# Uninstall release
helm uninstall release-name

# Get release information
helm get values my-mariadb
helm get notes my-mariadb

Working with MariaDB Example

Installation and Setup

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# Install MariaDB
helm install my-mariadb bitnami/mariadb --namespace devops

# Get root password (Bash)
kubectl get secret --namespace devops my-mariadb \
  -o jsonpath="{.data.mariadb-root-password}" | base64 -d

# Get root password (PowerShell)
$encoded = kubectl get secret --namespace devops my-mariadb `
  -o jsonpath="{.data.mariadb-root-password}"
$decoded = [System.Text.Encoding]::UTF8.GetString([System.Convert]::FromBase64String($encoded))
Write-Output $decoded

# Connect to MariaDB
kubectl run my-mariadb-client --rm --tty -i \
  --restart='Never' \
  --image docker.io/bitnami/mariadb:11.1.3-debian-11-r0 \
  --namespace devops \
  --command -- bash

Best Practices

  1. Version Control

    • Always specify chart versions
    • Use semantic versioning
    • Lock dependencies versions

  2. Values Management

    • Use separate value files for different environments
    • Document all configurable values
    • Use reasonable defaults

  3. Security

    • Never store secrets in values files
    • Use Kubernetes secrets
    • Implement RBAC

  4. Deployment

    • Use namespaces
    • Set resource limits
    • Configure health checks

Common Helm Commands Reference

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# Repository operations
helm repo add repo-name url
helm repo update
helm repo list
helm repo remove repo-name

# Chart operations
helm install release-name chart-name
helm upgrade release-name chart-name
helm uninstall release-name
helm list
helm history release-name
helm rollback release-name revision

# Values and configuration
helm get values release-name
helm get notes release-name
helm show values chart-name
helm show chart chart-name

# Debugging
helm lint chart-path
helm template chart-path
helm install --dry-run --debug

Working with Values

Viewing and Modifying Values

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# Get chart default values
helm show values bitnami/mariadb > values.yaml

# Get current release values
helm get values my-release

# Install/Upgrade with multiple value files
helm install -f values1.yaml -f values2.yaml my-release bitnami/mariadb

Common Value Operations

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# values.yaml example
mariadb:
  auth:
    rootPassword: "mypassword"
  primary:
    persistence:
      size: "8Gi"
  replication:
    enabled: true

Chart Development

Creating New Charts

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# Create new chart
helm create mychart

# Lint chart
helm lint mychart

# Package chart
helm package mychart

# Install local chart
helm install my-release ./mychart

Chart Structure

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mychart/
  ├── Chart.yaml          # Chart metadata
  ├── values.yaml         # Default values
  ├── charts/             # Dependent charts
  ├── templates/          # K8s manifest templates
  │   ├── deployment.yaml
  │   ├── service.yaml
  │   └── _helpers.tpl    # Template helpers
  └── README.md

Debugging and Troubleshooting

Debug Installation

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# Dry run installation
helm install --dry-run --debug my-release bitnami/mariadb

# Test release
helm test my-release

# View release history
helm history my-release

Common Troubleshooting Commands

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# Get MariaDB root password (Bash)
kubectl get secret --namespace default my-mariadb \
  -o jsonpath="{.data.mariadb-root-password}" | base64 -d

# Get MariaDB root password (PowerShell)
$encoded = kubectl get secret --namespace default my-mariadb `
  -o jsonpath="{.data.mariadb-root-password}"
[System.Text.Encoding]::UTF8.GetString([System.Convert]::FromBase64String($encoded))

# Connect to MariaDB pod
kubectl run my-mariadb-client --rm --tty -i \
  --restart='Never' \
  --image docker.io/bitnami/mariadb:11.1.3-debian-11-r0 \
  --namespace default \
  --command -- bash

Common Helm Hooks

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annotations:
  "helm.sh/hook": pre-install,post-install
  "helm.sh/hook-weight": "5"
  "helm.sh/hook-delete-policy": hook-succeeded

Available hooks:

  • pre-install
  • post-install
  • pre-delete
  • post-delete
  • pre-upgrade
  • post-upgrade
  • pre-rollback
  • post-rollback
  • test

Chart Testing

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# Install chart-testing
ct lint --all
ct install --all

# Run tests
helm test release-name

# Debug templates
helm template --debug mychart

Production Considerations

  1. High Availability

    • Enable replication when available
    • Use PodDisruptionBudgets
    • Configure proper resource requests/limits

  2. Monitoring

    • Enable metrics
    • Configure Prometheus exports
    • Set up proper logging

  3. Backup and Recovery

    • Configure persistent storage
    • Set up backup solutions
    • Document recovery procedures

  4. Scaling

    • Configure HorizontalPodAutoscaler
    • Set proper resource requests
    • Use node affinity rules when needed