Dependencies

This section of the guide covers best practices for dependencies declared in Chart.yaml.

Versions

Where possible, use version ranges instead of pinning to an exact version. The suggested default is to use a patch-level version match:

  1. version: ~1.2.3

This will match version 1.2.3 and any patches to that release. In other words, ~1.2.3 is equivalent to >= 1.2.3, < 1.3.0

For the complete version matching syntax, please see the semver documentation.

Prerelease versions

The above versioning constraints will not match on pre-release versions. For example version: ~1.2.3 will match version: ~1.2.4 but not version: ~1.2.3-1. The following provides a pre-release as well as patch-level matching:

  1. version: ~1.2.3-0

Repository URLs

Where possible, use https:// repository URLs, followed by http:// URLs.

If the repository has been added to the repository index file, the repository name can be used as an alias of URL. Use alias: or @ followed by repository names.

File URLs (file://...) are considered a “special case” for charts that are assembled by a fixed deployment pipeline.

When using downloader plugins the URL scheme will be specific to the plugin. Note, a user of the chart will need to have a plugin supporting the scheme installed to update or build the dependency.

Helm cannot perform dependency management operations on the dependency when the repository field is left blank. In that case Helm will assume the dependency is in a sub-directory of the charts folder with the name being the same as the name property for the dependency.

Conditions and Tags

Conditions or tags should be added to any dependencies that are optional.

The preferred form of a condition is:

  1. condition: somechart.enabled

Where somechart is the chart name of the dependency.

When multiple subcharts (dependencies) together provide an optional or swappable feature, those charts should share the same tags.

For example, if both nginx and memcached together provide performance optimizations for the main app in the chart, and are required to both be present when that feature is enabled, then they should both have a tags section like this:

  1. tags:
  2.   - webaccelerator

This allows a user to turn that feature on and off with one tag.