When we begin with Kubernetes, we are writing a lot of commands or yaml files to generate all the elements we need. But, at a time, we have a lot of similar elements to create for each service, and we don't want to spend a lot of time on it.
So to help you on your Kubernetes deployments, you can use Helm.
Based on Jinja2, you can add a lot of dynamism to your deployments.
First, what is Jinja?
Jinja is a templating language for python for web pages.
It can :
- display variables value dynamically
<li><a href="{{ user.url }}">{{ user.username }}</a></li>
- repeat a specific pattern for all the elements of the list
{% for user in users %}
<li><a href="{{ user.url }}">{{ user.username }}</a></li>
{% endfor %}
- display specific parts based on a variable value
{% if 'priority' in data %}
<p>Priority: {{ data['priority'] }}</p>
{% endif %}
- ...
Second, how to use helm?
Setup helm
When helm is installed, you have to create your Chart. It will contain the next files:
- Chart.yaml: Will contains the chart definition
- values.yaml: Will contains the default input values
- .helmignore optional: Contains the file list to ignore when building a project
-
templates: Directory which contains all your yaml files.
- _internal optional : An optional file to create some values, based on other input values.
- your yaml files: Your yaml files to generate your secrets, deployments, and more! It's here where you can use the Jinja template!
Install chart
When your chart is ready, you can install it! It will deploy all your yaml files in the chart.
Command to install it
helm install
Then you can add a lot of options to the command
- -f : Import a yaml file to override your default values
- -n : Namespace where to deploy the elements
- --set-string = : Will override a value
- ...
Go check the documentation to have the list of all the options. (https://helm.sh/docs/helm/helm_install/)
Upgrade chart
Then you can upgrade your chart
helm upgrade
Uninstall chart
And when you want to delete it, you can use the following command
helm uninstall
The power of helm
It's quite cool to be able to add dynamism to your installations. But sometimes, you don't want to rewrite something to install a tool on Kubernetes.
So here is Artifact Hub!
Like Docker and its dockerhub, Helm gets its own public repo where you can find a lot of charts for a lot of tools!
Example with grafana
Links
- Website Helm: https://helm.sh/
- Website Jinja2: https://jinja.palletsprojects.com/en/2.11.x/
- Artifact Hub: https://artifacthub.io/
If you want to go further:
- What is Helm in Kubernetes? by TechWorld by Nana : https://www.youtube.com/watch?v=-ykwb1d0DXU
- What is Helm? by IBM Cloud : https://www.youtube.com/watch?v=fy8SHvNZGeE
- Using Helm and Kubernetes on Baeldung : https://www.baeldung.com/kubernetes-helm
I know it's a quick show of Helm, but I hope it will help you! 😀
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