Hosting HELM chart private repositories in GitHub and GitLab

Helm is a popular tool for Kubernetes package manager. This article introduces what is Helm and how to host private helm repositories.

The package manager for Kubernetes

Official site

Helm is a popular tool for Kubernetes package manager. Helm contains 3 main concepts.

A "Repo" is a charts registry. You can add your own registry.

The official Helm stable repo is popular. You can add repos with following commands.

$ helm repo add stable https://kubernetes-charts.storage.googleapis.com/
$ helm repo update
$ helm search repo stable
NAME                                    CHART VERSION   APP VERSION                     DESCRIPTION
stable/acs-engine-autoscaler            2.2.2           2.1.1                           DEPRECATED Scales worker nodes within agent pools
stable/aerospike                        0.2.8           v4.5.0.5                        A Helm chart for Aerospike in Kubernetes
stable/airflow                          4.1.0           1.10.4                          Airflow is a platform to programmatically autho...
stable/ambassador                       4.1.0           0.81.0                          A Helm chart for Datawire Ambassador
...

A "Chart" is the term used for a package. A "Chart" is a collection of files that describe a related set of Kubernetes resources.

$ helm show chart stable/aerospike
apiVersion: v1
appVersion: v4.5.0.5
description: A Helm chart for Aerospike in Kubernetes
home: http://aerospike.com
icon: https://s3-us-west-1.amazonaws.com/aerospike-fd/wp-content/uploads/2016/06/Aerospike_square_logo.png
keywords:
- aerospike
- big-data
maintainers:
- email: kavehmz@gmail.com
  name: kavehmz
- email: okgolove@markeloff.net
  name: okgolove
name: aerospike
sources:
- https://github.com/aerospike/aerospike-server
version: 0.3.2

When a chart is installed, the Helm library creates a release to track that installation. A single chart may be installed many times into the same cluster, and create many different releases.

Release names always changed when we install charts.

We can set release name with a parameter.

$ helm install [RELEASE_NAME] stable/aerospike

Or we can use generated values.

$ helm install --generate-name stable/aerospike

Values provide a way to override template defaults with your own information.

We can check templates with values.

$ helm template stable/aerospike -f test_values.yml

And we can install with values.

$ helm install --generate-name stable/aerospike -f test_values.yml

helm v3.0.3

We can use GitLab Pages in a Public Repository. We need running GitLab runner to publish GitLab Pages.

# .gitlab-ci.yml
pages:
  image:
    name: linkyard/docker-helm
    entrypoint: ["/bin/sh", "-c"]
  stage: deploy
  script:
    - helm init --client-only
    - mkdir -p ../public
    - "echo \"User-Agent: *\nDisallow: /\" > ../public/robots.txt"
    - helm package * --destination ../public
    - echo https://${CI_PROJECT_NAMESPACE}.gitlab.io/${CI_PROJECT_NAME}
    - helm repo index --url https://${CI_PROJECT_NAMESPACE}.gitlab.io/${CI_PROJECT_NAME} .
    - mv index.yaml ../public
    - mv ../public .
  artifacts:
    paths:
      - public
  only:
    - master

After that

helm repo add mygitlab https://t-amachi.gitlab.io/helm-catalogs/

If you use index.yaml we need to build a new server which hosts index.yaml.

But helm v3 can evaluate OCI format, so we can use GitLab Packages.

At first, we create a new chart.

# OCI format is experimental feature
export HELM_EXPERIMENTAL_OCI=1

helm registry login -u tomoyamachi --password <token> https://registry.gitlab.com/

helm chart save map-collector gitlab.com/tomoyamachi/catalog:v0.0.1

helm chart list
#>
# 
helm chart push gitlab.com/tomoyamachi/catalog:v0.0.1

Then we try to fetch the target chart in another environment.

helm registry login -u tomoyamachi --password <token> https://registry.gitlab.com/
export HELM_EXPERIMENTAL_OCI=1
helm chart pull gitlab.com/tomoyamachi/catalog:v0.0.1
helm chart list

Now we can use the catalog chart in this environment.

When using GitHub, we use https://raw.githubusercontent.com.

You only need to set the index.yaml to the root path of the target repository.

helm repo add my-public-github https://raw.githubusercontent.com/tomoyamachi/helm-catalogs/master

You can provide a username and password(token) with parameters.

helm repo add --username tomoyamachi --password $TOKEN my-private-github https://raw.githubusercontent.com/tomoyamachi/helm-catalogs/master