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Helm

  • Chart

    A chart is (see example)

    • A collection of Kubernetes manifests (yaml) files which may contain template placeholders for some values
    • values files that can be injected into the templates
    • Chart.yaml file containing eg name and version of chart

    A chart can in a (local) directory, or in an archive (local or remote) of such a directory - called a package

    The

  • Chart (Dir)

    • Directory containing chart files, located by a dir path

  • (Chart) Package

    • A chart dir zipped into a tar.gz

  • (Chart) Repository

    • collection of chart packages (online)

    • add a remote repository to (local) cache/index (which can later be referenced via local_repo_ref)

      • helm repo add <local_repo_ref> <remote_repo_url>

  • (Chart) Repository Cache

    • local snapshot/link to a repository (like local git repo links to remote, on which it can fetch/pull/push)
    • see repo commands
  • Chart Location

    A charts location can be specified (necessary for many helm commands) by

  • Install

    • you can install a (local or remote) chart to your kubernetes cluster, which creates a so-called release in the cluster.

    • each release has a unique name and version which helm stores in metadata in a Kubernetes secret in the cluster

    • you pass the install command the chart location (dir_path, file_path or url)

    • installing a chart

      • 1). renders manifest files (ie injects values) in-memory
      • 2). calls kubectl apply -f on these files
    • you can query installed charts with helm ls and helm status
  • Package Manager Helm

    • Logical Application

      • A chart (package) usually corresponds to multiple containers working together as one (logical) application.

    • Dependency Resolution

      • Charts can specify dependencies on other charts. Helm can automatically resolve and download these dependencies from specified repositories (eg bitnami), similar to how package managers work in software development. Helm ensures that dependencies are installed before the chart that depends on them. This is particularly useful for complex applications where the order of deployment and interdependencies between different components (like databases, caching systems, etc.) matter.

  • Registry

    • A collection of repository metainfo in human readable webpages, making them easer to discover and navigate. When you find an interesting repo here in WebBrowser, you can use point helm at the link listed for the repo in question. The Registry doesnt maintain the repo content, just its meta data
    • eg ArtifactHub or bitnami (ArtifactHub contains bitnami and other providers)

  • Help

    helm help
    • get help on a (sub) command helm help ls 
      .....
Aliases:
    list, ls