Helm installs charts into Kubernetes, creating a new release for each installation. And to find new charts, you can search Helm chart repositories.
Helm Chart Repository
A Repository is the place where charts can be collected and shared. It’s like Perl’s CPAN archive or the Fedora Package Database, but for Kubernetes packages.
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$ helm search repo bitnami
NAME CHART VERSION APP VERSION DESCRIPTION
bitnami/bitnami-common 0.0.9 0.0.9 DEPRECATED Chart with custom templates used in ...
bitnami/airflow 8.0.2 2.0.0 Apache Airflow is a platform to programmaticall...
bitnami/apache 8.2.3 2.4.46 Chart for Apache HTTP Server
bitnami/aspnet-core 1.2.3 3.1.9 ASP.NET Core is an open-source framework create...
Chart
A Chart is a Helm package. It contains all of the resource definitions necessary to run an application, tool, or service inside of a Kubernetes cluster. Think of it like the Kubernetes equivalent of a Homebrew formula, an Apt dpkg, or a Yum RPM file.
Directory structure
wordpress/
Chart.yaml # A YAML file containing information about the chart
LICENSE # OPTIONAL: A plain text file containing the license for the chart
README.md # OPTIONAL: A human-readable README file
values.yaml # The default configuration values for this chart
values.schema.json # OPTIONAL: A JSON Schema for imposing a structure on the values.yaml file
charts/ # A directory containing any charts upon which this chart depends.
crds/ # Custom Resource Definitions
templates/ # A directory of templates that, when combined with values,
# will generate valid Kubernetes manifest files.
templates/NOTES.txt # OPTIONAL: A plain text file containing short usage notes
Pull:
helm pull chartrepo/chartname
Get info:
helm show chart bitnami/mysql
Install:
$ helm install bitnami/mysql --generate-name
NAME: mysql-1612624192
LAST DEPLOYED: Sat Feb 6 16:09:56 2021
NAMESPACE: default
STATUS: deployed
REVISION: 1
TEST SUITE: None
NOTES: ...
List installed:
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Chart Types
The type field defines the type of chart. There are two types: application and library. Application is the default type and it is the standard chart which can be operated on fully. The library chart provides utilities or functions for the chart builder. A library chart differs from an application chart because it is not installable and usually doesn’t contain any resource objects.
Release
A Release is an instance of a chart running in a Kubernetes cluster. One chart can often be installed many times into the same cluster. And each time it is installed, a new release is created. Consider a MySQL chart. If you want two databases running in your cluster, you can install that chart twice. Each one will have its own release, which will in turn have its own release name.
To keep track of a release’s state, or to re-read configuration information, you can use helm status:
$ helm status happy-panda
NAME: happy-panda
LAST DEPLOYED: Tue Jan 26 10:27:17 2021
NAMESPACE: default
STATUS: deployed
REVISION: 1
NOTES:
** Please be patient while the chart is being deployed **
