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Kubernetes Tool - HELM

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Kubernetes Tool - HELM

Helm

Helm chart
- a package for Kubernetes that bundles together all the resource definitions and configurations needed to run an application.
- a package manager for k8s
helm cli
- the utility to execute helm operations.
chart
- a collection of files that contain the instruction in the k8s
release
- a single installation of an application
- created when a chart is applied to k8s cluster.
- can use one chart to create multiple releases
- can use release name to track each release
revision
- the snapshot of the application
- created when a change is made to the application
repository
- a hub to store charts, can be public or private.
- multiple repos are available
  - Appscode
  - TrueCharts
  - Bitnami
  - Community Operators
- all repos are listed on ArtifactHub.io
metadata
- a place where store the data of the cluster.
- commonly is saved as k8s secrets in the cluster.
templating:
- to pass value to chart file

Common chart files

values.yaml: define values to be used in the charts
Chart.yaml: contains information about the chart itself
- e.g., api version, app version
- 2 types of chart:
  - application, default type
  - library
Common file structure
- project/
  - charts/: dependency charts
  - templates/
  - Chart.yaml
  - values.yaml
  - README.md

Lifecycle Management

release is created when helm install
- indepently from each other by release name
upgrade a release to a new revision
- helm upgrade nginx-release bitnami/nginx
- helm history nginx-release: show the app history
Rollback a release to the revision 1
- helm rollback nginx-release 1
- note: only rollback the cluster object, not the data, like user data.

Install helm

Windows

choco install kubernetes-helm

Ubuntu

sudo apt-get install curl gpg apt-transport-https --yes
curl -fsSL https://packages.buildkite.com/helm-linux/helm-debian/gpgkey | gpg --dearmor | sudo tee /usr/share/keyrings/helm.gpg > /dev/null
echo "deb [signed-by=/usr/share/keyrings/helm.gpg] https://packages.buildkite.com/helm-linux/helm-debian/any/ any main" | sudo tee /etc/apt/sources.list.d/helm-stable-debian.list
sudo apt-get update
sudo apt-get install helm

Imperative Command

Helm configuration

Command	Description
`helm env`	Prints out information about the local Helm environment variables.
`helm version`	Shows the installed version of the Helm client.

Chart Management (Local Development)

Command	Description
`helm create DIR`	Create a new directory with the default chart template files.
`helm lint DIR`	Examines a chart for possible issues and best practices.
`helm template DIR`	Out the all manifest of a chart
`helm template RELEASE REPO/CHART`	Out the all manifest of a repo’s chart
`helm package DIR`	Bundles the chart directory into a versioned .tgz archive file.

Install Release

Command	Description
`helm install RELEASE REPO/CHART`	Install a release from a chart within a repo.
`helm install RELEASE REPO/CHART --version VERSION`	Install a release from a chart of a version.
`helm install RELEASE REPO/CHART --set key=val`	Install a release from a chart within a repo and set values.
`helm install RELEASE REPO/CHART --values VALUE_YAML`	Install a release from a chart within a yaml file of values
`helm install RELEASE CHART_DIR`	Install a release from a local chart.
`helm install RELEASE CHART_ZIP`	Install a release from a local zipped chart.
`helm install RELEASE REMOTE_URL`	Install a release from a remote url.
`helm install RELEASE CHART --repo REPO_URL`	Install a release from a remote repo.
`helm install RELEASE CHART_DIR --dry-run=client`	Output all generated chart manifests
`helm install RELEASE CHART_DIR --debug`	Enable verbose output

Release Management

Command	Description
`helm list`	Lists all of the releases for current namespace
`helm list -a`	Show all releases
`helm list -A`	List releases across all namespaces
`helm list -n NAMESPACE`	List releases for a specific namespaces
`helm list -f 'ara[a-z]+'`	Filter releases
`helm list -l STRING`	Filter by labels
`helm status RELEASE`	Displays the real-time state of a deployed release.
`helm get values RELEASE`	Shows the specific values (–set or values.yaml) used for a release.
`helm history RELEASE`	Lists the revision history of a specific release.
`helm upgrade RELEASE CHART_DIR`	Upgrade release from a local chart
`helm upgrade RELEASE RELEASE/CHART`	Upgrade release from repo chart
`helm upgrade RELEASE RELEASE/CHART --version=VERSION`	Upgrade release to a version from repo chart
`helm rollback RELEASE VERSION`	Reverts a release to a specific previous revision.
`helm uninstall RELEASE`	Removes all resources associated with a release from the cluster.

Repository Management

Command	Description
`helm search repo REPO`	Searches added repositories for specific charts.
`helm search hub KEYWORD`	Search for Helm charts in the Hub
`helm repo list`	List chart repositories
`helm repo add REPO URL`	Connects local Helm client to a remote chart repository.
`helm repo update`	Gets the latest information of all charts
`helm repo update REPO`	Gets the latest information of a chart
`helm repo index CHART_DIR`	Create an index file given a directory containing packaged charts
`helm repo remove REPO`	Remove one or more chart repositories
`helm pull`	Downloads a chart from a remote repository to current path.
`helm pull --untar`	Downloads and unzip a chart from a remote repository to current path.

repo info

CMD	DESC
`helm show all REPO/CHART`	show all information of the chart
`helm show chart REPO/CHART`	show the chart’s definition
`helm show crds REPO/CHART`	show the chart’s CRDs
`helm show values REPO/CHART`	show the chart’s values
`helm show readme REPO/CHART`	show the chart’s README
`helm show readme REPO/CHART`	show the chart’s README
`helm get values RELEASE`	get the release value

Lab: Repo Management

Add repo

helm repo add traefik https://traefik.github.io/charts
# "traefik" has been added to your repositories

helm repo update
# Hang tight while we grab the latest from your chart repositories...
# ...Successfully got an update from the "traefik" chart repository
# Update Complete. ⎈Happy Helming!⎈

helm repo list
# NAME    URL
# traefik https://traefik.github.io/charts

helm search repo traefik
# NAME                    CHART VERSION   APP VERSION     DESCRIPTION
# traefik/traefik         38.0.2          v3.6.6          A Traefik based Kubernetes ingress controller
# traefik/traefik-crds    1.13.1                          A Traefik based Kubernetes ingress controller
# traefik/traefik-hub     4.2.0           v2.11.0         Traefik Hub Ingress Controller
# traefik/traefik-mesh    4.1.1           v1.4.8          Traefik Mesh - Simpler Service Mesh
# traefik/traefikee       4.2.5           v2.12.5         Traefik Enterprise is a unified cloud-native ne...
# traefik/maesh           2.1.2           v1.3.2          Maesh - Simpler Service Mesh

# download
helm pull traefik/traefik

ls -lh traefik-38.0.2.tgz
# -rw-r--r-- 1 ubuntuadmin ubuntuadmin 294K Jan 18 17:43 traefik-38.0.2.tgz

Show info

helm show chart traefik/traefik
# annotations:
#   artifacthub.io/changes: |
#     - "revert(CRDs): use Traefik Hub v3.18.0 compatible crds"
#     - "fix(security): set the seccomp profile to RuntimeDefault"
#     - "fix(CRDs): enforce the fact that this Chart does not support Traefik Hub v3.19.0"
#     - "feat(deps): update traefik docker tag to v3.6.6"
#     - "chore(release): publish traefik 38.0.2 and crds 1.13.1"
# apiVersion: v2
# appVersion: v3.6.6
# description: A Traefik based Kubernetes ingress controller
# home: https://traefik.io/
# icon: https://raw.githubusercontent.com/traefik/traefik/master/docs/content/assets/img/traefik.logo.png
# keywords:
# - traefik
# - ingress
# - networking
# kubeVersion: '>=1.22.0-0'
# maintainers:
# - email: michel.loiseleur@traefik.io
#   name: mloiseleur
# - email: remi.buisson@traefik.io
#   name: darkweaver87
# - name: jnoordsij
# name: traefik
# sources:
# - https://github.com/traefik/traefik-helm-chart
# - https://github.com/traefik/traefik
# type: application
# version: 38.0.2

# show crd
helm show crds traefik/traefik

# show values
helm show values traefik/traefik

# show readme
helm show readme traefik/traefik