Helm
Kubernetes has already gained popularity as a leading container orchestration system. Helm plays an important role in managing the application.
Helm helps us to define, install, and upgrade complex Kubernetes applications.One can use helm to template everything.
Components to know in Helm:
Chart: A helm package having all definitions required to run applications or service in Kubernetes cluster.
Repository: A shared location for keeping charts.
Release: A version of a chart which is running the cluster.
Let’s start by using helm.
As it works with Kubernetes, so we need to install it before using it. Let’s install a Kubernetes cluster.
Now download the helm client. Its a open source available on git. https://github.com/helm/helm/releases
Or we can use below script.
curl https://raw.githubusercontent.com/helm/helm/master/scripts/get-helm-3 > get_helm.sh
chmod 700 get_helm.sh
./get_helm.sh
or use below commands
# Brew
brew install kubernetes-helm
# Choco
choco install kubernetes-helm
# Gofish
gofish install helm
How to use:
Add or search
There are cases where we need to search and use a template from public domain, like internet.
We can use this command: “helm search hub”. For example : “helm search hub drupal”
We can add repositories to our system and then search helm from this internal space.
First, add a repo using “helm repo add alias url” and then we can search using “helm search repo alias”
Install
Now let’s install the package using “helm install release package”
Changing default values
For example, we are installing WordPress using the helm template and its already in our repo.
The first step is to find the values in helm template
Use the command : “helm show values wordpress”
It will show all the values in helm template.
Now create a .yml file that has those values and we can override few values that we need.
You can then override any of these settings in a YAML formatted file, and then pass that file during installation.
Now, we can use that file to install and override settings.
Use the command : “helm install -f settings.yaml wordpress”
Charts
We can store all templates in directory folder.
values.yaml has the default values of a chart.
Chart.yaml contains description of chart.