• Is a package system for k8s
• The config contains configuration information that can be merged into a packaged chart to create a releasable object.
• A release is a running instance of a chart, combined with a specific config.

Module structure

chart.yaml

• metadata for the chart
• dependencies
• The chart is a bundle of information necessary to create an instance of a Kubernetes application.

values.yaml

• values, similar to terraform
• the configuration to the charts
• custom values are supported from CLI, like terraform

templates

• basically k8s yaml with variables
• prevents duplication of the code
• combined templates and values gives us a valid k8s yaml

test

• tests for deployed infrastructure

Helm.hub and tools

• search charts, ready to use
• monocular — self hosted chart repository
• there is a linter and tester for charts
• there is a migrator from 2 to 3. A plugin
• chart releaser — to help me to run my own chart repository
• drone - CI for helm
• airship — from openstack project, works with helm
• there is a helm provider for terraform

Commands

helm repo add bitnami https://charts.bitnami.com/bitnami
helm search repo bitnami
helm repo update              # Make sure we get the latest list of charts
helm install bitnami/mysql --generate-name
helm show chart bitnami/mysql
helm show all bitnami/mysql
helm status myrelease # shows all the details about your release
helm list # shows revisions, what has been installed, versions
helm rollback mydelease 1 # rollsback to revision 1
helm delete myrelease # deletes all what you deployed, all of it, keeping track of what has been deployed
helm uninstall mysql-1612624192
—dry-run # to see the incoming changes
helm install testrelease .

Architecture

• Helm Client — CLI
  • Local chart development
  • Managing repositories
  • Managing releases
  • Interfacing with the Helm library
    • Sending charts to be installed
    • Requesting upgrading or uninstalling of existing releases
• Helm Library — connects to k8s API
  • Combining a chart and configuration to build a release
  • Installing charts into Kubernetes, and providing the subsequent release object
  • Upgrading and uninstalling charts by interacting with Kubernetes

Links

• https://www.youtube.com/watch?v=Zzwq9FmZdsU&t=2s