How to Pull Environment Variables with Helm Charts

Helm Chart is widely regarded as the package manager for Kubernetes. While it may appear to be just another package manager, it extends a great deal more. Helm makes managing application components easy by grouping those parts into charts, which can then be easily installed and upgraded.

What is Helm Charts?

Helm charts leverage a packaging format. A chart is a collection of files that define a related set of Kubernetes resources. A single chart might be used to deploy something as simple as a Memcached pod, or it could be used to deploy something as complex as a full web app stack, complete with HTTP servers, databases, and caches. Charts are developed as files laid out in a particular directory structure. They can be made into versioned archives to be deployed.

How Do Helm Charts Work?

• The Helm application library uses charts to define, build, install, and upgrade Kubernetes applications.
• You may manage Kubernetes manifests using Helm charts instead of the Kubernetes command-line interface (CLI).
• You don't have to remember complex Kubernetes commands to manage the cluster.
• Consider a practical scenario in which Helm can be useful, you intend to deploy your application in a production environment with ten replicas.
• Now, test the same application in a staging environment. environment. Using Helm, you can customize the fields based on the surroundings.

How To Pull Environment Variables With Helm Charts?

Here is the step-by-step implementation to pull environment variables with Helm Charts:

Step 1: Create a Helm Chart

First, Use the helm create command to start a new Helm chart.

helm create my-chart

Output:

Step 2: Create Directory Structure

Below is the generated directory structure and files created by the helm create command.

my-chart/
├── .helmignore
├── Chart.yaml
├── values.yaml
├── charts/
└── templates/
    ├── deployment.yaml
    ├── service.yaml
    ├── hpa.yaml
    ├── ingress.yaml
    ├── serviceaccount.yaml
    ├── tests/
    │   └── test-connection.yaml
    └── _helpers.tpl

Step 3: Add Environment Variables

Values will have added to your environment variables.yam. For example.

env:
  - name: DATABASE_URL
    value: "mysql://user:password@host:port/db"
  - name: SECRET_KEY
    valueFrom:
      secretKeyRef:
        name: my-secret
        key: secret-key

Step 4: Review and Update

You can get metadata for your chart in the Chart. yaml.

apiVersion: v2
name: webapp
description: A Helm chart for deploying a basic Nginx web application
type: application
version: 0.1.1
appVersion: 1.22.0

Step 5: Modify the Deployment Template

Next, open the file templates/deployment.yaml and fill in the container specification with the environment variables.

apiVersion: apps/v1
kind: Deployment
metadata:
  name: my-app
spec:
  replicas: 1
  selector:
    matchLabels:
      app: my-app
  template:
    metadata:
      labels:
        app: my-app
    spec:
      containers:
        - name: my-app-container
          image: my-app-image:latest
          env:
            {{- with .Values.env }}
            {{- toYaml . | nindent 12 }}
            {{- end }}

Step 6: Deploy the Helm Chart

Now, The install option must be a chart reference, a path to a packaged chart, a route to an unpacked chart directory, or a URL.

helm install my-release ./my-chart

Output:

Step 7: Check Deployment

Then you can find out how your deployment is progressing.

kubectl get deployments

Output:

Step 8: Update the Helm Chart with Personalized Values

Now you can also update with personalized values to enhance the process.

helm upgrade my-release ./my-chart -f override-values.yaml

Output:

Step 9: Verify Updated Deployment

Lastly, running the below command may show an extensive overview of the deployment's settings, status, and other pertinent information.

kubectl describe deployment my-app

Output:

Best Practices of Helm charts

• Use Templates Effectively: You need to break large, complicated templates into smaller, more manageable ones. For common templates and functions, use _helpers. tpl.
• Package/push, then deploy: This is the recommended method for utilizing Helm. First, you should package and submit the Helm chart to a repository, after which you deploy it to your cluster.
• Deploy from an unpackaged chart: This is the simplest Helm pipeline. The Helm chart and the application's source code are in the same Git repository.
• Manage Dependencies Properly: To manage chart dependencies, use Chart. yaml or the charts/ directory. This guarantees that all necessary charts are present and accessible.

Conclusion

In this article, we have learned about how to pull environment variables with Helm charts. A Helm chart combines YAML files with templates to generate configuration files based on specified criteria.