Helm
The Kubernetes Package Manager.
What is helm?
Helm is a kubernetes resource templating tool. Where all the defined kubernetes resources are deployed with combinations of templates and values. Therefore it is called the kubernetes package manager.
A helm-package, or a helm-chart is a folder with a set file-structure.
+-- altinn-designer
| +-- templates
| | +-- tests
| | | +-- test-connection.yaml
| | +-- NOTES.txt
| | +-- _helpers.tpl
| | +-- deployment.yaml
| | +-- service.yaml
| | +-- ingress.yaml (deleted in altinn studio, since we don't use ingress. But an ingress template is included in a default helm-chart)
| +-- .helmignore
| +-- Chart.yaml
| +-- values.yaml
The Chart.yaml-file contains information about the chart, like the name, version and maintainers.
The values.yaml-file contains different values. These values are accessable in the templates. So different environment variables can be defined in the values. Values can also be overwritten when running a upgrade or install of the chart.
The files in the templates-folder becomes populated with the values, and sent to the kubernetes clusters as the name of the files. So deployment.yaml should create a deployment in kubernetes. The same fore service.yaml and ingress.yaml.
_helpers.tpl can be used to define functions to get release names, concatinated with other info.
NOTES.txt is the info printed in the cli after an install or upgrade of an release, usually used to give usefull commands the user can run to access the pods.
Helm usage in Altinn Studio
We use helm to deploy our builds to the kubernetes cluster, both in development-, production- and SBL-cluster. Azure Dev Ops pipelines have support for helm, so this makes deploying to development trigger everytime we merge some code into master.