Kubernetes Package Administration with Helm¶

1.0 - Helm Installation and Configuration¶

1.1 - Helm Overview¶

Helm: A package manager for Kubernetes.
Used to define Kubernetes applications in charts.
Using charts and Helm, one can:
Manage complexity
Easily update and rollback
Share Charts
Helm v3 includes a number of changes:
Tiller removed, one would have to run helm init.
Helm search supports local repositories and against helm hub
Command overhaul, helm init is no longer required for example
Releases are scoped to namespaces
Chart API and Dependency Managers have been updated.
Tiller was a server-side component with helm to help deployment. This meant it had extensive advanced permissions, which posed a huge security risk; its removal mitigates this risk.

Charts¶

Charts are a collection of YAML files that would be typically used to deploy Kubernetes resources.
By wrapping the desired YAML files e.g. those associated with an application, management and deployment is made significantly easier.

1.2 - Environment Setup¶

Tools required:
VS Code
Docker
Kubernetes (can also use minikube, k3d, etc.)

1.3 - Installation¶

Ensire all prerequisites are installed.
Installation via any desired method:
From binary
Script Install
Package Managers (apt, chocolatey, homebrew, etc.)

1.4 - Configuration¶

Common commands:
helm version
helm repo add - Adds a chart repository to the system
helm search repo - Search a repo for a desired chart version
helm install - Deploy all kubernetes objects defined in a particular chart, --dry-run flag is also available
helm list - Get list of any releases (installed charts)
Managing releases:
- helm upgrade
- helm rollback
- helm history
Creating charts:
- helm create - Creates a chart with default files and structure
- helm package - Create a chart archive from a chart directory, which can be pushed to a repo

1.5 - Configuration Demo¶

Add the stable repository: helm repo add stable https://charts.helm.sh/stable
Verify addition: helm repo list
Search the repo for a chart: helm search repo <repo name>/chart name
Example: helm search repo stable/mysql

2.0 - Exploring Helm Releases¶

2.1 - Deploying a Chart to Kubernetes¶

Releases = Instance of a chart running in Kubernetes.
Add a repo via helm repo add <repo name> <repo link>
Search for the chart you want, using mysql as an example from the stable repo: helm search repo <repo name>/<chart name>
Install the chart: helm install <release name> <repo name>/<chart name>
By default, if no version is provided, the latest version will be used.

2.2 - Chart Deployment Demo¶

To view chart information in the CLI, use helm show: helm show chart stable/mysql
Displays information such as sources, keywords, apiVersion, appVersion, and a description of the chart.
To view the README: helm show readme <repo name>/<chart name>
For ease, the README can be piped to a file for viewing, append > /path/to/README.txt for example
Displays parameters such as prerequisites and image(s) used
Chart install general command: helm install <release name> <repo name>/<chart name>
Append --dry-run --debug for a test run and verbose output.
Verify release via helm list

2.3 - Retrieving Information on Helm Releases¶

Once a release has been deployed, the state of the release can be inspected by helm list
By default, helm list will only check in the default namespace
For releases in other namespaces, use --namespace <namespace> or --all-namespaces
To view the status of the objects, use standard kubectl commands.

2.4 - Helm Release Information Retrieval Demo¶

helm list to check the release
Check the status of a release helm status <release name>
Shows information such as chart version
Manifest version helm get manifest <release name> > <filename>
Shows the kubectl manifest YAMLs of all objects created, supplied with default values
For custom values used during release deployment: helm get values <release name> > /path/to/file
Get the notes associated with a chart: helm get notes <release name> > /path/to/file
To get everything: helm get all <release name> > /path/to/file
Use kubectl get all to get all kubernetes resources
View helm chart release history: helm history <release name>
Provides details around all versions of a release
Uninstall release but keep history: helm uninstall <release name> --keep-history
Re-running without the --keep-history flag will completely uninstall the chart.

2.5 - Upgrading a Release¶

To view all versions of a chart: helm search repo <repo name>/<chart name> --version
To install a specific version: helm install <release name> <repo name>/<chart name> --version <version>
Use helm status and kubectl commands to verify deployment
To upgrade a release, use helm upgrade <release name> <repo name>/<chart name> --version <new version>
New resources (where required) will then be created
Use helm list to review the release information and helm history to show the changes between revisions.

2.6 - Release Upgrade Demo¶

Search for the repo helm search repo <repo name>/<chart name>
Get all versions of the chart helm search repo <repo name>/<chart name> --versions
Deploy the desired chart version: helm install <release name> <repo name>/<chart name> --version <version>
Verify deployment with helm list
Check the kubernetes objects kubectl get all (or appropriate e.g. use --namespace)
Upgrade the release helm upgrade <release name> <repo name>/<chart name> --version <new version>
Verify upgrade with helm list
View the history of the release helm history <release name>

2.7 - Rolling Back a Release¶

In the event of a rollback, use helm rollback <release name> <revision number>
Use helm list and kubectl commands to verify deployment again

2.9 - Exploring a Chart¶

To pull down a chart from a remote repository and view the files: helm pull <repo>/<chart name> --untar
Charts by default contain the following:
Chart.yaml - Contains chart description
Values.yaml - Contains default values for the chart if not provided
Charts folder - Contains other charts that the main chart is dependent upon
Templates folder - Contains the primary YAML files used to generate Kubernetes Manifests
Under templates folder, the manifests used to create Kubernetes objects e.g. deployments, services, etc.
_helpers.tpl - Used for supporting functions to be referenced by YAML files in the template directories
Notes.txt - Contains help text for the charts.
Template YAMLs use Jinja templating to pass through variables / values set for the Helm chart, such as:
name: {{ .Release.name }}-deployment
image: {{ .Values.containerImage }}
Values can be changed at runtime e.g. you may have specific values for Development and Production environments.

3.0 - Configuring Helm Repositories¶

3.1 - Repository Overview¶

Chart repository = Any HTTP server that can serve YAML or TAR files. Needs to be able to respond to GET requests.
Contains an index.yaml file and packaged charts.
Helm charts are commonly stored in the Helm hub at https://hub.helm.sh
Helm charts can then be stored and managed within the UI.

3.2 - Packaging a Helm Chart¶

To create a chart: helm create <chart name>
Initializes a chart folder with the default files and structure.
Default files included:
Templates folder:
- tests folder: To store any tests defined to verify chart functionality
- _helpers.tpl - Used to define supporting functions for template YAMLs.
- Example YAML files for Kubernetes resources - deployment, ingress, service account.
- Notes.txt - Contains chart deployment information e.g. "how to get started with it"
Add the desired YAML files required for the chart under Templates.
Install the chart: helm install <chart name> /path/to/chart
Verify deployment with helm list and kubectl commands as required.
Packaging the chart: helm package <path to chart> --destination <path to local charts folder>

3.3 - Packaging a Helm Chart Demo¶

Create a chart: helm create <chart name>
Check and make whatever edits are necessary to the chart folder in ./<chart name> e.g. remove the default YAML folders.
Add content to the Notes.txt file under templates directory
Deploy the chart: helm install <release name> /path/to/chart
Verify with helm list and kubectl commands
Delete the release: helm delete <release name>
If required, update the Jinja template directives e.g. {{ .Release.Name }} or {{ .Values.containerImage }}
Redeploy if required using the commands defined above.
Use more detailed commands to verify customised values are set accordingly e.g. -o jsonpath=<path to metadata>
To override a value defined in values.yaml, use --set <value key>=<new value>.
Package the chart: helm package <path to chart> <output path>

3.4 - Creating a Local Helm Repository¶

Chart museum - an open-source, cross-platform helm chart repository that supports multiple cloud backends and local usage
Chart museum itself can be ran as a helm chart.
Deployment: helm install chartmuseum stable/chartmuseum --set env.open.DISABLE_API=false
DISABLE_API allows pushing of chart repository.
To connect, port-forwarding is required: kubectl port-forward $POD_NAME 8080:8080 --namespace default
Pod name can be obtained by $POD_NAME=$(kubectl get pods -l "app=chartmuseum" -o jsonpath="{.items[0].metadata.name}")
Add chart museum repository: helm repo add chartmuseum http://127.0.0.1:8080
Push to chart to chart museum: curl --data-binary "@<chart tar name>" http://localhost:8080/api/charts
Searching chart museum:
Run helm repo update to update the chart-museum repository to recognize the pushed chart.
Verify update with helm search repo chartmuseum/<chart name>

3.6 - Creating a Remote Helm Repository¶

A Helm Repository can be any server that can serve YAML and TAR files, as well as responding to get requests.
Options available include Chart Museum, Github, JFrog Artifactory

3.6.1 - Example: Github Repository¶

Create a repository in Github via standard means and clone locally.
Copy in the packaged chart (the .tgz file created via helm package)
In the repo, run helm repo index - creates index.yaml, the file referenced by helm search
Stage, commit, then push to the repository.
Add Github repository as a local Helm repository:
Copy the RAW URL of the index.yaml file (minus the index.yaml)
Run helm repo add <repo name> <RAW URL>
Search for the repo: helm search repo <repo name>/<chart name>
The index.yaml has been cached locally and is getting picked up by helm search.