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The Chart Repository Guide

This section explains how to create and work with Helm chart repositories. At a high level, a chart repository is a location where packaged charts can be stored and shared.

The official chart repository is maintained by the Kubernetes Charts, and we welcome participation. But Helm also makes it easy to create and run your own chart repository. This guide explains how to do so.

Prerequisites

Go through the Quickstart Guide
Read through the Charts document

Create a chart repository

A chart repository is an HTTP server that houses an index.yaml file and optionally some packaged charts. When you're ready to share your charts, the preferred way to do so is by uploading them to a chart repository.

Note: For Helm 2.0.0, chart repositories do not have any intrinsic authentication. There is an issue tracking progress in GitHub.

Because a chart repository can be any HTTP server that can serve YAML and tar files and can answer GET requests, you have a plethora of options when it comes down to hosting your own chart repository. For example, you can use a Google Cloud Storage (GCS) bucket, Amazon S3 bucket, Github Pages, or even create your own web server.

The chart repository structure

A chart repository consists of packaged charts and a special file called index.yaml which contains an index of all of the charts in the repository. Frequently, the charts that index.yaml describes are also hosted on the same server, as are the provenance files.

For example, the layout of the repository https://example.com/charts might look like this:

charts/
  |
  |- index.yaml
  |
  |- alpine-0.1.2.tgz
  |
  |- alpine-0.1.2.tgz.prov

In this case, the index file would contain information about one chart, the Alpine chart, and provide the download URL https://example.com/charts/alpine-0.1.2.tgz for that chart.

It is not required that a chart package be located on the same server as the index.yaml file. However, doing so is often the easiest.

The index file

The index file is a yaml file called index.yaml. It contains some metadata about the package, including the contents of a chart's Chart.yaml file. A valid chart repository must have an index file. The index file contains information about each chart in the chart repository. The helm repo index command will generate an index file based on a given local directory that contains packaged charts.

This is an example of an index file:

apiVersion: v1
entries:
  alpine:
    - created: 2016-10-06T16:23:20.499814565-06:00
      description: Deploy a basic Alpine Linux pod
      digest: 99c76e403d752c84ead610644d4b1c2f2b453a74b921f422b9dcb8a7c8b559cd
      home: https://k8s.io/helm
      name: alpine
      sources:
      - https://github.com/kubernetes/helm
      urls:
      - https://technosophos.github.io/tscharts/alpine-0.2.0.tgz
      version: 0.2.0
    - created: 2016-10-06T16:23:20.499543808-06:00
      description: Deploy a basic Alpine Linux pod
      digest: 515c58e5f79d8b2913a10cb400ebb6fa9c77fe813287afbacf1a0b897cd78727
      home: https://k8s.io/helm
      name: alpine
      sources:
      - https://github.com/kubernetes/helm
      urls:
      - https://technosophos.github.io/tscharts/alpine-0.1.0.tgz
      version: 0.1.0
  nginx:
    - created: 2016-10-06T16:23:20.499543808-06:00
      description: Create a basic nginx HTTP server
      digest: aaff4545f79d8b2913a10cb400ebb6fa9c77fe813287afbacf1a0b897cdffffff
      home: https://k8s.io/helm
      name: nginx
      sources:
      - https://github.com/kubernetes/charts
      urls:
      - https://technosophos.github.io/tscharts/nginx-1.1.0.tgz
      version: 1.1.0
generated: 2016-10-06T16:23:20.499029981-06:00

A generated index and packages can be served from a basic webserver. You can test things out locally with the helm serve command, which starts a local server.

$ helm serve --repo-path ./charts
Regenerating index. This may take a moment.
Now serving you on 127.0.0.1:8879

The above starts a local webserver, serving the charts it finds in ./charts. The serve command will automatically generate an index.yaml file for you during startup.

Hosting Chart Repositories

This part shows several ways to serve a chart repository.

Google Cloud Storage

The first step is to create your GCS bucket. We'll call ours fantastic-charts.

Next, make your bucket public by editing the bucket permissions.

Insert this line item to make your bucket public:

Congratulations, now you have an empty GCS bucket ready to serve charts!

You may upload your chart repository using the Google Cloud Storage command line tool, or using the GCS web UI. This is the technique the official Kubernetes Charts repository hosts its charts, so you may want to take a peek at that project if you get stuck.

Note: A public GCS bucket can be accessed via simple HTTPS at this address https://storage.googleapis.com/bucket-name.

Github Pages example

In a similar way you can create charts repository using GitHub Pages.

GitHub allows you to serve static web pages in two different ways:

By configuring a project to serve the contents of its docs/ directory
By configuring a project to serve a particular branch

We'll take the second approach, though the first is just as easy.

The first step will be to create your gh-pages branch. You can do that locally as.

$ git checkout -b gh-pages

Or via web browser using Branch button on your Github repository:

Next, you'll want to make sure your gh-pages branch is set as Github Pages, click on your repo Settings and scroll down to Github pages section and set as per below:

By default Source usually gets set to gh-pages branch, if not do so select it.

You can use a custom domain there if you wish so.

And check that Enforce HTTPS is ticked, so the HTTPS will be used when charts are served.

In such setup you can use master branch to store your charts code, and gh-pages branch as charts repository, e.g.: https://USERNAME.github.io/REPONAME. The demonstration TS Charts repository is accessible at https://technosophos.github.io/tscharts/.

Ordinary web servers

To configure an ordinary web server to serve Helm charts, you merely need to do the following:

Put your index and charts in a directory that the server can serve
Make sure the index.yaml file can be accessed with no authentication requirement
Make sure yaml files are served with the correct content type (text/yaml or text/x-yaml)

For example, if you want to serve your charts out of $WEBROOT/charts, make sure there is a charts/ directory in your web root, and put the index file and charts inside of that folder.

Managing Chart Repositories

Now that you have a chart repository, the last part of this guide explains how to maintain charts in that repository.

Store charts in your chart repository

Now that you have a chart repository, let's upload a chart and an index file to the repository. Charts in a chart repository must be packaged (helm package chart-name/) and versioned correctly (following SemVer 2 guidelines).

These next steps compose an example workflow, but you are welcome to use whatever workflow you fancy for storing and updating charts in your chart repository.

Once you have a packaged chart ready, create a new directory, and move your packaged chart to that directory.

$ helm package docs/examples/alpine/
$ mkdir fantastic-charts
$ mv alpine-0.1.0.tgz fantastic-charts/
$ helm repo index . --url https://storage.googleapis.com/fantastic-charts

The last command takes the path of the local directory that you just created and the URL of your remote chart repository and composes an index.yaml file inside the given directory path.

Now you can upload the chart and the index file to your chart repository using a sync tool or manually. If you're using Google Cloud Storage, check out this example workflow using the gsutil client. For GitHub, you can simply put the charts in the appropriate destination branch.

Add new charts to an existing repository

Each time you want to add a new chart to your repository, you must regenerate the index. The helm repo index command will completely rebuild the index.yaml file from scratch, including only the charts that it finds locally.

However, you can use the --merge flag to incrementally add new charts to an existing index.yaml file (a great option when working with a remote repository like GCS). Run helm repo index --help to learn more,

Make sure that you upload both the revised index.yaml file and the chart. And if you generated a provenance file, upload that too.

When you're ready to share your charts, simply let someone know what the URL of your repository is.

From there, they will add the repository to their helm client via the helm repo add [NAME] [URL] command with any name they would like to use to reference the repository.

$ helm repo add fantastic-charts https://storage.googleapis.com/fantastic-charts
$ helm repo list
fantastic-charts    https://storage.googleapis.com/fantastic-charts

Note: A repository will not be added if it does not contain a valid index.yaml.

After that, your users will be able to search through your charts. After you've updated the repository, they can use the helm repo update command to get the latest chart information.

Under the hood, the helm repo add and helm repo update commands are fetching the index.yaml file and storing them in the $HELM_HOME/repository/cache/ directory. This is where the helm search function finds information about charts.

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