Cloud-Native Microservices With Kubernetes - 2nd Edition

Charts, Releases, and Repositories

A chart is a collection of files that describe a related set of Kubernetes resources. A single chart can define a simple application, like a Redis instance, or a complex one, like a complete web application stack with web servers, databases, and caches.

When you install a chart in a Kubernetes cluster, this creates a new release of that chart.

A repository is a place where charts are stored, versioned, and shared. A repository can contain multiple charts, and you can add or reference multiple repositories in your Helm configuration.

A chart is a collection of files that is organized as follows (an example from a WordPress chart):

wordpress/
  # A YAML file containing information
  # about the chart
  Chart.yaml
  # OPTIONAL: A plain text file containing
  # the license for the chart
  LICENSE
  # OPTIONAL: A human-readable README file
  README.md
  # The default configuration values for this chart
  values.yaml
  # OPTIONAL: A JSON Schema for imposing a
  # structure on the values.yaml file
  values.schema.json
  # A directory containing any charts
  # upon which this chart depends.
  charts/
  # Custom Resource Definitions
  crds/
  # A directory of templates that,
  # when combined with values,
  # will generate valid Kubernetes manifest files.