Helm Reference

4 min read | by Jordi Prats

Helm is a package manager for Kubernetes that simplifies the management of applications on a Kubernetes cluster, allowing you to define, install, and upgrade applications and their dependencies using charts, which are essentially packages that contain all the necessary information for deploying an application.

CLI

• helm: set array using CLI: Set list of values using helm cli options
• Helm: Get values set for an installed application: Using helm get values we can retrieve the valued we set for a given application
• Helm: list applications: helm as any package manager can also list all the installed applicacions on a kubernetes cluster
• Helm: show values: To customize a helm chart it is advisable to do it using the values.yaml file
• Helm options to wait for the deployment to be in a healthy state: Using the wait option while upgrading a helm application helps realizing if something goes wrong
• helm: Rollback an upgrade: When upgrades goes south, we can rollback to a previous versions using helm rollback
• Helm diff using a plugin: If you are familiar with the yaml files of a given application, it can come handy to be able to see the differences before upgrading an application using helm
• helm: get rendered yaml files before applying them: before helm install or upgrade we can take a look the actual yaml files
• helm upgrade history: helm history prints historical revisions for a given release

Releases

• Github action to release a helm chart: We can use github actions and github pages to release a helm chart
• Helm conditional dependencies: helm optional dependencies
• Helm dependencies: helm can handle chart dependencies
• helm: Create chart template: How to get started creating helm charts
• Creating a helm package an repo: How to create your own helm repo

Templates

• helm: Import files into ConfigMap or Secret: Import files into ConfigMap or Secret objects using helm
• Helm: fullname template in range block: To use the fullname template in a range block we will have to create a local variable
• Helm: wrong type for value; expected string; got chartutil.Values: A definition cannot be used on another definition across template files
• Helm templates: Select an element of an array: Using the index function we can retrieve elements of an array on a Helm template
• Helm: Using define and include: By combining define and include we can include multiple times the same data
• Helm: Join an Array into a string: Using join on a helm template we can create a string out of an array
• Helm hooks: Using the helm hooks we can define objects that will be applied under certain conditions
• helm - how to write if/else and expressions: The helm template engine syntax is the most challenging to learn
• Context in go templates is important: can't evaluate field Values in type interface {} might sound obscure, it's all about the context

k3s

• helm on k3s: Kubernetes cluster unreachable: Install helm on k3s nodes: Kubernetes cluster unreachable

Secrets

• How are stored the Helm values: Depending on the helm version chart values can be stored on a ConfigMap or a Secret

Terraform

• Apply helm using terraform: To deploy on kubernetes, we can either define the actual manifests, but it's far more practical to just relay on helm

Dependencies

• helm: set a value for a dependency: When you are using some charts as dependencies you might need to set a different default value for a given dependency