This article was originally posted on the , a self-described “package manager for Kubernetes,” alleviates some of this complexity.
In this guide, you’ll learn all you need to know to get started with Helm, including its core components and features and what the Helm workflow looks like. Finally, you’ll see how Helm streamlines Kubernetes DevOps to equip your team for better efficiency.
What Is Helm?
Helm acts as a layer of abstraction on top of your typical Kubernetes workflow. Rather than manually applying manifests when you want to deploy or modify an application, you can use the Helm CLI client to create, find, install, modify, and uninstall charts. In Helm’s terminology, a of packages. While you will typically use the latest version when installing a chart, Helm package archives are versioned, so it is possible to specify a particular version of a package, much like other package managers you may be familiar with.
This means that if you maintain Helm charts, you can make incremental updates and publish new versioned archives as needed, while the old ones can remain available to have historical records or for legacy support.
Dependency Management
One of Helm’s benefits is its ability to help you install complex applications without manually setting everything up.
Complex applications often require a number of dependencies. If you were to set up an application from scratch, you would need to declare and manage the dependencies yourself.
Helm, however, has built-in dependency management: a chart declares its dependencies, and these will be set up and configured when the release is created.
Rollback Capabilities
If something goes wrong during a release, Helm makes it easy to revert to your previous working configuration through rollbacks.
Each time you install, upgrade, or roll back a release, your release’s revision number is incremented by 1. You can use this revision number to revert to a previous version of your release like so:
# helm rollback [RELEASE] [REVISION]
helm rollback my-release 1
To determine which revision to roll back to, you can view the revision history of a given release:
$ helm history my-release
REVISION UPDATED STATUS CHART APP VERSION DESCRIPTION
1 Tue Sep 10 09:26:54 2024 deployed wordpress-23.1.12 6.6.1 Install complete
How Does Helm Work?
Helm offers many options, and trying to understand them all at once can be overwhelming. However, you don’t need that to get started. You only have to know how Helm’s core features can be used together to form a workflow:
- Chart creation and packaging: If you’re packaging your own application, the first step is to create the necessary files. This can be done via
helm create NAME,which will generate some boilerplate files for you to modify. Once your application is configured, you can create a versioned archive if you want to distribute it. - Finding existing charts: Rather than packaging your own applications, you can also use Helm to find and download existing charts of other applications. You can use these charts to install and configure an application and its dependencies.
- Template rendering process: As part of the installation process, Helm combines your chart, templates, and values to to select the best method for your needs.
Once you have Helm installed and a Kubernetes cluster to use it with, you can try out some common workflows.
Basic Helm Commands
To use Helm, you’ll issue commands via the CLI client. Helm has quite a few commands, but the following are essential ones you should be aware of:
CODE# Install a chart
helm install <name> <chart>
CODE# Install a chart while setting values on the command line (can specify multiple or separate values with commas)
helm install <name> <chart> --set key1=val1,key2=val2
# Run a test installation to validate chart
helm install <name> <chart> --dry-run --debug
# Upgrade a release
helm upgrade <release> <chart>
# Upgrade a release, or install it if a corresponding release does not already exist
helm upgrade <release> <chart> --install
# Add a repository from the internet:
helm repo add <repo-name> <url>
# Update information of available charts locally from chart repositories
helm repo update
# Download a chart as a versioned archive
helm pull <chart>
The official documentation has a or a . Viewing the entry on the web shows that you can install the chart with its default settings by running this command:
CODEhelm install my-nginx oci://registry-1.docker.io/bitnamicharts/nginx
If you want to view or modify the chart before installing it, use the
helm pullcommand like so:
CODEhelm pull oci://registry-1.docker.io/bitnamicharts/nginx
This command downloads a versioned chart archive that you can view and modify as needed. You can also view the values supported by the chart to reveal any options you can modify and configure before installing:
CODEhelm show values oci://registry-1.docker.io/bitnamicharts/nginx
Specify any values you would like to change by defining them in a YAML file like
my-values.yamland pass it as an option when you install the chart, like so:
CODEhelm install my-nginx oci://registry-1.docker.io/bitnamicharts/nginx -f my-values.yaml
Deploying a Sample Application
Let’s now see how all of the above comes together when you install, upgrade, and roll back a simple application. A good example application to use for understanding Helm’s workflows is , as a self-service solution, bridges the gap and allows developers to safely deploy and manage applications without deep Kubernetes expertise. The internal developer platform comes with a built-in Helm manager that enables teams to manage Helm repositories, charts, and releases on clusters with a comprehensive interface. You can even sign up for free and deploy your first Helm chart effortlessly.
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