Helm chart

A Helm chart is a package of templated Kubernetes manifests plus default settings, installed with Helm, the Kubernetes package manager. One chart describes everything an application needs, such as Deployments, Services and ConfigMaps. Different values files turn the same chart into a dev, staging or production install.

How it works

A chart is a directory with Chart.yaml for its name and version, values.yaml for defaults, and a templates/ folder. Helm fills the templates with values and applies the result. Each install is a release with numbered revisions:

• helm upgrade --install api ./chart -f values-prod.yaml --set image.tag=1.4.2 deploys revision 7.

• helm rollback api 6 returns to the previous revision.

Helm keeps 10 revisions per release by default on upgrade. Charts are shared through repositories or OCI registries, and many teams render them through GitOps tools such as Argo CD.

Why it matters in production

Charts make deployments repeatable and reviewable across environments. They also hide what reaches the cluster, so run helm template or a diff in CI. Before a Kubernetes upgrade, check charts for removed API versions, or the upgrade breaks installs.

See also

• Kubernetes

• GitOps

• Container image

• Infrastructure as code

On the One2N blog

• Deploy REST API and its dependent services using Helm charts

• Best practices for upgrading EKS clusters

• Moving from traditional CD pipelines to GitOps

Further reading

• Helm documentation: charts