Helm

Helm allows you to create and use charts in your Kubernetes clusters. A Helm chart is a layer on top of your resources that logically combines them, and allows you to treat them as a single entity for their lifecycle.

An example: If you have an application that is comprised of 2 deployments, a namespace, a service account, and service. Without Helm you are creating and updating these items separately and individually. Helm allows you to group these into a chart as a single unit. Another benefit of Helm is the ability to parameterize certain aspects of this "application" (the manifests) so that you can specify different values from different requirements.

A chart can be either an ‘application' or a ‘library' chart.

Application charts are a collection of templates that can be packaged into versioned archives to be deployed.

Library charts provide useful utilities or functions for the chart developer. They're included as a dependency of application charts to inject those utilities and functions into the rendering pipeline. Library charts do not define any templates and therefore cannot be deployed.

Structure

foo/
├── .helmignore   # Contains patterns to ignore when packaging Helm charts.
├── Chart.yaml    # Information about your chart
├── values.yaml   # The default values for your templates
├── charts/       # Charts that this chart depends on
└── templates/    # The template files
    └── tests/    # The test files

Install

osx:

brew install helm

apt:

curl https://baltocdn.com/helm/signing.asc | gpg --dearmor | tee /usr/share/keyrings/helm.gpg > /dev/null
apt-get install apt-transport-https --yes
echo "deb [arch=$(dpkg --print-architecture) signed-by=/usr/share/keyrings/helm.gpg] https://baltocdn.com/helm/stable/debian/ all main" | tee /etc/apt/sources.list.d/helm-stable-debian.list
apt-get update
apt-get install helm

Jenkins Chart:

helm repo add jenkins https://charts.jenkins.io

helm search repo jenkins

Repo

helm repo add bitnami https://charts.bitnami.com/bitnami

helm search repo bitnami/word

helm show readme bitnami/wordpress

Use

helm list --all-namespaces

helm get manifest redis-stack-server -n redis

Render chart with template

helm template is a command-line tool provided by Helm, the Kubernetes package manager. It allows you to render Helm charts locally without installing them onto a Kubernetes cluster. This command generates Kubernetes YAML manifests based on the values provided in the chart's values.yaml file and any overrides you specify.

helm template mymysql bitnami/mysql

Values file

helm get values myrelease

helm show values oci://registry-1.docker.io/bitnamicharts/keycloak

Upgrade

Latest version will be specified unless the ‘–version' flag is set.

values

helm upgrade dashboard kubernetes-dashboard/kubernetes-dashboard --set="service.externalPort=8080,resources.limits.cpu=200m,metricsScraper.enabled=true"

reuse-values

helm upgrade --reuse-values bitnami/nginx mydeployname --version=18.1.0

CRD

Command to view the CRDs associated with the ArgoCD Helm chart. This can be useful for understanding the resources that ArgoCD will manage within your Kubernetes cluster.

helm show crds <chart>