Getting Started with Helm Chart

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Helm charts are configuration ymls which are used for managing the Kubernetes resources.

In the production environment where you are managing lots of Kubernetes resources then Helm Chart can be very helpful to manage those Kubernetes resources because managing each Kubernetes resource can be a little cumbersome and daunting task.

In this article, we will start from very basic -

  1. Install Helm Chart
  2. Writing your first Helm Chart for Hello World


1. Install Helm Chart

Installing the Helm Chart pretty easy but there is a pre-requisite of setting up Kubernetes Cluster.

If you do not have a Kubernetes cluster

Follow this guide for setting up Kubernetes cluster - Setup you Kubernetes cluster

1.1: Install Helm Chart Using Script

If you like doing everything from scratch then I would suggest you to install the Helm Chart Using script.

Run the following scripts -

1curl -fsSL -o get_helm.sh https://raw.githubusercontent.com/helm/helm/master/scripts/get-helm-3
1chmod 700 get_helm.sh
1./get_helm.sh

Verify the Installation - You can verify the installation by running the following command

1helm version
1WARNING: Kubernetes configuration file is group-readable. This is insecure. Location: /home/vagrant/.kube/config
2version.BuildInfo{Version:"v3.4.0", GitCommit:"7090a89efc8a18f3d8178bf47d2462450349a004", GitTreeState:"clean", GoVersion:"go1.14.10"}

1.2: Install Helm Chart Using Binary

The other option would be to download the complete binary and do the installation be yourself

Step 1 : Download the Binary

Step 2 : Extract the binary using the command

1tar -zxvf helm-vxxx-xxxx-xxxx.tar.gz

Step 3 : Move it to

1mv linux-amd64/helm /usr/local/bin/helm

Verify the Installation - You can verify the installation by running the following command

1helm version
1WARNING: Kubernetes configuration file is group-readable. This is insecure. Location: /home/vagrant/.kube/config
2version.BuildInfo{Version:"v3.4.0", GitCommit:"7090a89efc8a18f3d8178bf47d2462450349a004", GitTreeState:"clean", GoVersion:"go1.14.10"}

1.3: Install Helm Chart with package Manager

If you like package manager then you use the following install command based on your preference -

Homebrew

1brew install helm

Chocolatey

1choco install kubernetes-helm

Scoop

1scoop install helm

GoFish

1gofish install helm

Snap

1sudo snap install helm --classic

And do not forget to verify the installation

Verify the Installation - You can verify the installation by running the following command

1helm version
1WARNING: Kubernetes configuration file is group-readable. This is insecure. Location: /home/vagrant/.kube/config
2version.BuildInfo{Version:"v3.4.0", GitCommit:"7090a89efc8a18f3d8178bf47d2462450349a004", GitTreeState:"clean", GoVersion:"go1.14.10"}

2. Writing your first Helm Chart for “Hello World”

Now after you have done your Helm Chart installation, we can write our first “Hello World” Helm Chart.

To begin with -


2.1: Create your first Helm Chart

We are going to create our first helloworld Helm Chart using the following command

1helm create helloworld

It should create a directory helloworld, you can verify it by using the following ls -lart command

1ls -lart | grep helloworld

It should return you with -

1drwxr-xr-x 4 vagrant vagrant     4096 Nov  7 19:57 helloworld

To verify the complete directory structure of the HelmChart please do run the command

1tree helloworld 
 1helloworld
 2├── charts
 3├── Chart.yaml
 4├── templates
 5│  ├── deployment.yaml
 6│  ├── _helpers.tpl
 7│  ├── hpa.yaml
 8│  ├── ingress.yaml
 9│  ├── NOTES.txt
10│  ├── serviceaccount.yaml
11│  ├── service.yaml
12│  └── tests
13│      └── test-connection.yaml
14└── values.yaml
15

Great now you created your first Helm Chart - helloworld.

In the next steps we are going to run the helloworld Helm Chart.


2.2: Update the service.type from ClusterIP to NodePort inside the values.yml

Before you run your helloworld Helm Chart we need to update the service.type from ClusterIP to NodePort.

The reason for this change is - After installing/running the helloworld Helm Chart we should be able to access the service outside of the kubernetes cluster. And if you do not change the service.type then you will only be able to access the service withing kubernetes cluster.

To update the values.yml, first go inside the directory helloworld

1cd helloworld

2.2.1: Open values.yml in vi

After that open the `values.yml` in `vi`
1vi values.yaml 

2.2.2: Update service.type from ClusterIP to NodePort

Look for the service.type block and update its value to NodePort

1service:
2  type: NodePort
3  port: 80

2.3: Install the Helm Chart using command - helm install

Now after updating the values.yml, you can install the Helm Chart.

Note : The helm install command take two arguments -

  1. First argument - Release name that you pick
  2. Second argument - Chart you want to install

It should look like -

1helm install <FIRST_ARGUMENT_RELEASE_NAME> <SECOND_ARGUMENT_CHART_NAME>

Your final command would be

1helm install myhelloworld helloworld

After running the above command it should return you with -

 1NAME: myhellworld
 2LAST DEPLOYED: Sat Nov  7 21:48:08 2020
 3NAMESPACE: default
 4STATUS: deployed
 5REVISION: 1
 6NOTES:
 71. Get the application URL by running these commands:
 8  export NODE_PORT=$(kubectl get --namespace default -o jsonpath="{.spec.ports[0].nodePort}" services myhellworld-helloworld)
 9  export NODE_IP=$(kubectl get nodes --namespace default -o jsonpath="{.items[0].status.addresses[0].address}")
10  echo http://$NODE_IP:$NODE_PORT

2.4: Verify the helm install command

Now you need to verify your helm release .i.e. myhelloworld and which can be done by running the helm list command.

1helm list -a

It should return you withe release name which you have just installed .i.e. myhelloworld

1NAME       	NAMESPACE	REVISION	UPDATED                              	STATUS  	CHART           	APP VERSION
2myhelloworld	default  	1       	2020-11-07 21:48:08.8550677 +0000 UTC	deployed	helloworld-0.1.0	1.16.0

2.5: Get kubernetes Service details and port

Lets run the kubectl get service command to get the NodePort.

1kubectl get service

And the above command should return you -

1NAME                     TYPE        CLUSTER-IP      EXTERNAL-IP   PORT(S)        AGE
2kubernetes               ClusterIP   10.233.0.1      <none>        443/TCP        14d
3myhellworld-helloworld   NodePort    10.233.14.134   <none>        80:30738/TCP   7m10s

Note: Keep in mind the NodePort number can vary in the range 30000-32767, so you might get different NodePort.

Since my cluster ip is 100.0.0.2 and NodePort is 30738, so I can access my Nginx page of my myhelloworld Helm Chart


3. Helm: Adding upstream repositories

We have apt,yum,dnf package manager in Linux distros, similarly Helm relies on bitnami chart repositories and Chart Developer can create YAML configuration file and package them into charts and publish it as chart repositories.

For Example - You want to deploy Redis in-memory cache inside your kubernetes cluster from Helm repository, so you can simply run the following command -

1helm install redis bitnami/redis

Note: The above command will search for the redis chart inside bitnami chart repository and then it will install the redis chart inside your kubernetes cluster.

3.1 How to ADD upstream Helm chart repository

There are five repo commands provided by Helm which can be used for add,list,remove,update,index the chart repository.

  1. add : Add chart repository
  2. list : List chart repository
  3. update : Update the chart information locally
  4. index : For generating the index file
  5. remove : Remove chart repository
3.1.1: ‘add’ Helm Chart repository

To add any chart repository you should know the name and repository url.

Example - We are going to add bitnami repository.

So our command should look like

1helm repo add <REPOSITORY_NAME> <REPOSITORY_URL>

Here is the final command

1helm repo add bitnami https://charts.bitnami.com/bitnami

z

Verify the repository
1helm search repo bitnami

It should return you back with all the charts which are available inside bitnami repository

1NAME                            	CHART VERSION	APP VERSION  	DESCRIPTION                                       
2bitnami/bitnami-common          	0.0.8        	0.0.8        	Chart with custom templates used in Bitnami cha...
3bitnami/airflow                 	6.7.1        	1.10.12      	Apache Airflow is a platform to programmaticall...
4bitnami/apache                  	7.6.0        	2.4.46       	Chart for Apache HTTP Server                      
5bitnami/aspnet-core             	0.3.3        	3.1.9        	ASP.NET Core is an open-source framework create...
6bitnami/cassandra               	6.0.6        	3.11.8       	Apache Cassandra is a free and open-source dist...
7bitnami/common                  	0.10.0       	0.10.0       	A Library Helm Chart for grouping common logic ...
8bitnami/consul                  	8.0.4        	1.8.4        	Highly available and distributed service discov...
9

3.1.2: ‘list’ Helm Chart repository

In the previous step we have added the bitnami repository, lets run the list command for listing the repositories we have added so far.

1helm repo list

It should return you back with

1NAME   	URL                               
2bitnami	https://charts.bitnami.com/bitnami

3.1.3: ‘update’ Helm Chart repository

In the previous two steps we have seen - How to add and list the Helm Repositories.

Lets see how you can update your helm repositories. (The update command is necessary if haven’t updated your Helm chart repository in a while, so might miss some recent changes)

Here is the command to update Helm repository

1helm repo update

Once your update has completed you should see following message on your console

1Hang tight while we grab the latest from your chart repositories...
2...Successfully got an update from the "bitnami" chart repository
3Update Complete. ⎈Happy Helming!⎈

3.1.4: ‘index’ Helm Chart repository

The index command can be used for generating the index file of given directory which contains the packaged charts.

So in our case we have created a chart named helloworld, now we are going to create index.yaml for it.

Run the following command -

1helm repo index helloworld

The above command should create index.yaml inside your packaged charts directory.

1cat helloworld/index.yaml 
1apiVersion: v1
2entries: {}
3generated: "2020-11-08T10:28:18.544761158Z"

3.1.5: ‘remove’ Helm Chart repository

If in case you want to remove certain repositories then Helm provides remove command which can be used for removing the repositories.

In the previous steps we have added bitnami repositories, so now we are going to remove the same repositories using the remove command

1helm repo remove bitnami

After the successful removal you should see the following message

1"bitnami" has been removed from your repositories