Helm is a really strong tool that you should look into if you’re exploring Kubernetes. It is a package management tool for Kubernetes that manages the deployment of Helm charts, which are collections of pre-configured Kubernetes application resources.
Helm includes nearly every command required for easier app administration in a Kubernetes cluster. In this blog, we will look into Helm and learn about several helpful Helm commands in the Helm command cheat sheet.
What is Helm?
As mentioned above, Helm is a package management tool for Kubernetes, but it is also used for a variety of other purposes and has a broad range of capabilities. Its primary purpose is to handle Kubernetes YAML files that are developed by Kubernetes projects. Helm Charts are used to carry out the tasks. Charts are collections of Kubernetes manifests used to create, edit, and delete Kubernetes resources including pods, deployments, and services.
Helm charts are made up of child charts and dependent charts, which together form a project’s whole dependency tree. Instead of performing reams of codes through Kubectl and file downloading organizations, the users just need to execute a single command for installing complete applications. Helm charts also allow users to create several versions of manifest files. As a result, the users would be able to quickly retrieve certain chart revisions. Helm saves the record of deployed charts so that the users may revert to previous versions in the event of an emergency. Because Helm and Kubernetes have improved their interaction, the users no longer need to write complicated syntax files or anything else to use Helm. Other uses of Helm include:
- Installing software, as well as their dependencies, automatically.
- Updating software regularly, as well as configuring deployments.
- Getting a package from repositories and making the job go even faster and easier.
- Offers a command-line tool that enables customers to access all of Helm’s features.
- It’s designed using a servant component known as a “tiller”. It’s also deployed to every Kubernetes cluster, and its primary role is to perform all commands issued by the Helm, as well as to manage cluster settings.
Basic Helm Concepts
- Helm has a package called Chart, which is by far the most essential Helm element. It is the collection of Kubernetes YAML declarations that have been bundled together for convenience. Helm charts make it feasible to launch the containerized applications with only one command. They’re organized into repositories, which are online collections. The charts are easy to find, acquire, and deploy since the repositories have dedicated names and URLs.
- Helm Hub is an online repository that hosts several distributed repositories. It functions as a resource center where you can locate programs as well as their repository locations. It is not feasible to install an app straight via Helm Hub at this time.
- Release is a chart’s instance or deployment. Right after executing the Helm install command on your Kubernetes cluster, a new release gets created for that chart.
Helm Commands Cheat Sheet
Let’s jump into the Helm command cheat sheet, which includes all the frequently-used Helm commands. However, one should ensure to go through the following prerequisites first:
- A Kubernetes cluster, that can be created easily through minikube
- The pre-configured Helm package manager
1. Installing and Uninstalling Apps
Helm’s main purpose is to manage Kubernetes apps. Helm allows you to run test installs and modify the installation process to fit your needs, in addition to the fundamental functions of installing and uninstalling applications.
The command for installing the app:
helm install [name] [chart]
Installing the applications for particular namespaces:
helm install [name] [chart] –namespace [namespace]
Overriding the default configurations with the one specified in the file defined by the user:
helm install [name] [chart] –values [yaml-file/url]
Running a test installation for validating and verifying charts:
helm install [name] –dry-run –debug
Uninstalling releases:
helm uninstall [release]
2. Finding and Viewing Charts
Run the following command for adding remote chart repositories. This creates a repository, which is a collection of charts. Many charts may be found in repositories, that are also available at open-source repository servers:
helm repo add [name] [url]
By making the use of Helm search, users can search for charts or all of your system’s repositories (repo option):
$ helm search hub prometheus
For viewing the information about a particular chart, or their value, run the Helm show command along with the chart or values:
$ helm show chart concourse/concourse
$ helm show values concourse/concourse
3. Installing and Managing Charts
Finding and installing charts on a Kubernetes cluster is perhaps the most typical way users utilize Helm. The following are the most common commands used while installing charts.
Run the following command for installing the chart’s dependencies. If you need to download a dependency that you indicated in your Chart.yaml:
helm dependency update
The following command will help individuals to install a chart from a repository. This will help them in ensuring that the repository is configured first.
helm install myapp-instance sourcerepo/myapp
Installing charts with reference through URLs. Doing this will enable users for specifying URLs to the repository during installation:
helm install –repo http://charts.example.com my-app-instance myapp
Installing charts from a packed file:
helm install myapp-instance ./path/to/myappchart.tgz
Installing Helm chart from unpacked chart directory. It is extremely beneficial when users are developing charts locally, or the chart is not published on public repositories:
helm install myapp-instance ./path/to/chart
For installing templates that overrule configurations defined in the file. For doing so, use -f in the install command. Keep in mind that executing this command will override all the default values:
helm install -f ./my-extra-values.yml ./mychart
For installing Helm charts that can override their default values directly from the command line::
helm install –set key1=val1,key2=val2 [name] [chart]
4. Getting Information about Deployed Charts
Run the following command for listing all the releases or charts that are deployed on your Kubernetes clusters:
helm list
The below-mentioned command will help individuals to get the YAML file for all of the objects that are composed of all the releases of the objects created during the Helm installation:
helm get manifest <release-name>
Printing the status message of releases. This release gets created automatically every time a chart is deployed, and the following command will help is displaying the release:
helm status <release-name>
5. List and Search Repositories
To display and find Helm repositories, use the helm repo and helm search commands. You may use helm search to locate applications and repositories in Helm Hub.
All of the repositories (remote sources for obtaining charts) that you’ve added to your Helm installation are listed here:
$ helm repo list
Generating indexed files that can be found within the current directories:
helm repo index
Searching charts for keywords:
helm search [keyword]
Searching repositories on the basis of keywords:
helm search repo [keyword]
Searching Helm hum by making the use of keywords:
helm search hub [keyword]
6. Release Monitoring
The Helm lists tool lets you categorize releases in a Kubernetes cluster using many criteria, including regular expressions. Utilizing commands like Helm status and history, you can get more info about releases.
Listing the releases on all the namespaces that are ready:
helm list –all-namespaces
Listing releases in particular namespaces:
helm list –namespace [namespace]
Listing releases into the specific format defined by the user:
helm list –output [format]
Applying filters to the list of releases by utilizing expressions:
helm list –filter ‘[expression]’
Checking the current status of particular namespaces:
helm status [release]
Displaying the version history of releases:
helm history [release]
Displaying info about Helm’s client environment:
helm env
7. Chart Management
Helm charts create applications using Kubernetes resources. Creating a directory that contains common chart files such as Chart.yaml, values.yaml, charts/ and templates:
helm create [name]
Packaging charts into chart archives:
helm package [chart-path]
The command for run tests for checking the health of charts and figuring out the possible issue:
helm lint [chart]
Inspecting charts and listing their content:
helm show all [chart]
Downloading charts:
helm pull [chart]
Downloading a chart along with extracting the archived content directory:
helm pull [chart] –untar –untardir [directory]
Displaying all the chart dependencies:
helm dependency list [chart]
8. Developing Your Own Charts
Packaging software for using and operating them with Helm is the process of creating charts. For creating one from scratch, you have to first run the helm create command for initializing the creation of the chart on your system.
Thereafter run the below-mentioned command for creating your own chart. Right after executing it, a new skeleton or boilerplate chart at ./mychart will be developed that can be edited and customized as per your need.
helm create [path]
helm create mychart
For locally rendering the chart templates, execute the helm template command for showing up the output YAML directly from Helm chart. This will also be useful in debugging the charts:
helm template [NAME] [CHART]
helm template my-app-instance sourcerepo/my-app
helm template my-app-instance
Conclusion
Helm is a Kubernetes package management tool whose main function is to deal with Kubernetes YAML files created by Kubernetes projects. The duties are carried out using Helm Charts, which are the collections of Kubernetes manifests used for creating, editing, and deleting Kubernetes resources such as pods, deployments, and services.
Helm contains various commands needed for Kubernetes cluster application management. We hope that the above-mentioned Helm command cheat sheet, which contains the most commonly used Helm commands, would serve as a ready-reckoner while handling Kubernetes YAML files.