☸️ Some changes between Helm v2 and Helm v3 that you should know

#helm #devops #kubernetes

I was working on deploying an application on Kubernetes with Helm v3, then I decided to do the same while using Helm v2 this time to validate the possibility of migration from helm2 to helm3.

In this article, I want to share with you some of the changes between v2 & v3, that I faced in my task when I verified the validation of my Chart and when I deployed my application with these two helm versions.

Helm v3 introduces some changes in:

Adios Tiller
Helm v2 vs v3 commands.
Chart apiVersion.
Chart dependencies.
Helm package command.
Route object in chart.
helm search command.
How to migrate from helm2 to helm3?

1. Adios Tiller:

In Helm v3 tiller is gone, and there is only Helm client 😊.

2. Helm v2 vs v3 commands:

Some commands are not supported or renamed in Helm v3:

Command	Helm2	Helm3
Initialize Helm client/server	init
Download a chart to your local directory	fetch	pull
Given a release name, delete the release from Kubernetes	delete	uninstall
Helm client environment information		env
Displays the location of HELM_HOME	home
Inspect a chart	inspect	show
Uninstalls Tiller from a cluster	reset

3. Chart apiVersion:

Helm decides to increment the chart API version to v2 in Helm3:

# Chart.yaml
-apiVersion: v1 # Helm2
+apiVersion: v2 # Helm3
...

4. Chart dependencies:

Helm v2 chart has a specific file called 'requirements.yaml' where dependencies are added under the dependencies section. With Helm v3 this section are moved from requirements.yaml to Chart.yaml.

More information about this change can be found in the official documentation.

5. Helm package command:

Running helm package command with Helm v2 will raise a directory name (foo) and Chart.yaml name (bar) must match error if the Chart name does not match the Chart root folder name. With Helm v3 this constraint is not compulsory.

6. Route object in Chart:

Unlike the Helm v2, route object in Helm v3 chart requires host and status fields.

apiVersion: v1
kind: Route
metadata:
  name: {{ include "toto.name" . }}
spec:
+  host: {{ .Values.host }}
  to:
    kind: Service
    name: {{ include "toto.name" . }}
    weight: 100
  port:
    targetPort: 'http'
  wildcardPolicy: None
+status: 
+  ingress: []
+  wildcardPolicy: None

7. helm search command:

With helm v2 you can use helm search [CHART_NAME] command to search for a chart in both your repo list and in helm hub.

With Helm v3 you have to specifie where to look for your chart .

Usage:
  helm search [command]

Available Commands:
  hub         search for charts in the Helm Hub or an instance of Monocular
  repo        search repositories for a keyword in charts

8. How to migrate from helm2 to helm3:

Helm team made a good helm plugin called helm-2to3 that facilitates :