How Do I Use Helm to Deploy a Complex Application on Kubernetes?

Helm is a strong package manager for Kubernetes. It helps us deploy complex applications easily. With Helm, we can define, install, and manage applications using Helm Charts. Helm makes it simple to deploy and manage Kubernetes applications. It helps us handle dependencies, configurations, and updates. These tasks can be hard in a Kubernetes environment.

In this article, we will look at how to use Helm to deploy complex applications on Kubernetes. We will talk about what Helm is and why it is good for Kubernetes deployments. We will also guide you on how to install Helm on your local machine. We will explain Helm Charts and how they work. We will show you how to create custom Helm Charts. We will share best practices for structuring these charts. We will discuss how to manage configurations and secrets. We will explore real-world uses for Helm. Finally, we will explain how to upgrade and rollback applications easily.

  • How Can We Use Helm for Deploying Complex Applications on Kubernetes?
  • What is Helm and Why Should We Use It for Kubernetes Deployments?
  • How Can We Install Helm on Our Local Machine?
  • What Are Helm Charts and How Do They Work?
  • How Can We Create a Custom Helm Chart for Our Application?
  • What Are the Best Practices for Structuring Helm Charts?
  • How Can We Manage Configurations and Secrets with Helm?
  • What Are Real-World Use Cases for Using Helm in Kubernetes?
  • How Can We Upgrade and Rollback Applications with Helm?
  • Frequently Asked Questions

For more details on Kubernetes and its parts, check this article on what is Kubernetes and how it simplifies container management.

What is Helm and Why Use It for Kubernetes Deployments?

Helm is a helpful tool for managing packages in Kubernetes. It makes it easier to deploy and manage applications on Kubernetes clusters. With Helm, we can define, install, and upgrade even complex Kubernetes applications using simple commands.

Key Features of Helm:

  • Charts: Helm uses something called charts. Charts are groups of pre-set Kubernetes resources. They let us deploy applications with just one command.

  • Versioning: Helm supports versioning for charts. This means we can go back to earlier versions of our application easily if we need to.

  • Templating: Helm has a templating engine. This helps us to change the configuration of Kubernetes resources. It makes managing different environments like development, staging, and production easier.

  • Dependency Management: Helm can manage dependencies between different charts. It makes sure that all parts are deployed in the right order.

Why Use Helm for Kubernetes Deployments?

  1. Simplicity: Helm hides the complicated parts of Kubernetes resource definitions. This allows us to deploy applications with less effort.

  2. Reusability: We can reuse Helm charts in different projects or share them with our team. This helps us follow best practices and saves time.

  3. Configuration Management: We can manage changes to application settings using values files. This makes it easy to control how applications behave in different environments.

  4. Community Support: Helm has a big and active community. This means we can find many ready-to-use charts in public places like Artifact Hub.

  5. Integrated Workflows: We can easily add Helm to CI/CD pipelines. This helps us automate deployments and updates.

Using Helm for Kubernetes deployments makes everything simpler. It is a great choice for managing complex applications in cloud environments. For more information on how Helm works and to get started, check out this article on Helm and Kubernetes deployments.

How Do I Install Helm on My Local Machine?

To install Helm on our local machine, we can follow these steps based on our operating system.

For macOS

  1. Using Homebrew:

    brew install helm

  2. Verify Installation:

    helm version

For Windows

  1. Using Chocolatey:

    choco install kubernetes-helm

  2. Verify Installation:

    helm version

For Linux

  1. Using Snap (for distributions with Snap support):

    sudo snap install helm --classic

  2. Using Script (for any Linux distribution):

    curl https://raw.githubusercontent.com/helm/helm/master/scripts/get-helm-3 | bash

  3. Verify Installation:

    helm version

Installation from Binary

  1. Download the latest release:

    wget https://get.helm.sh/helm-v3.x.x-linux-amd64.tar.gz
tar -zxvf helm-v3.x.x-linux-amd64.tar.gz
sudo mv linux-amd64/helm /usr/local/bin/helm

  2. Verify Installation:

    helm version

After we install, we check if Helm is set up good by running helm version. This will show us that the Helm client is ready to use for deploying applications on Kubernetes.

What Are Helm Charts and How Do They Work?

Helm charts are packages of ready-made Kubernetes resources. They help us to deploy and manage applications on Kubernetes easily. Helm charts include all the needed YAML files to run an application. This includes deployments, services, and configurations. We package these files together as one unit.

Structure of a Helm Chart

A normal Helm chart has this directory structure:

mychart/
  Chart.yaml          # Information about the chart
  values.yaml         # Default settings
  charts/             # Any charts it depends on
  templates/          # Templates for Kubernetes resources

Key Components

  • Chart.yaml: This file has information about the chart. It includes the name, version, and dependencies.

  • values.yaml: This file defines default settings. Users can change these settings when they install the chart.

  • templates/: This folder holds the resource templates. These are regular Kubernetes manifests. They have placeholders that we fill with values from the values.yaml.

How Helm Charts Work

  1. Installation: We install charts into a Kubernetes cluster. This creates all the Kubernetes resources from the chart’s templates.

    helm install my-release mychart/

  2. Configuration: We can change deployments by overriding values in the values.yaml. We can do this with the --set flag or by making a custom values file.

    helm install my-release mychart/ --set image.tag=2.0

  3. Upgrades: We can change our application settings or resources by updating the chart and using the upgrade command.

    helm upgrade my-release mychart/

  4. Rollback: If an upgrade causes problems, we can easily go back to a previous version.

    helm rollback my-release 1

Example

Here is a simple deployment template in a Helm chart:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: {{ .Release.Name }}-app
spec:
  replicas: {{ .Values.replicaCount }}
  selector:
    matchLabels:
      app: {{ .Release.Name }}
  template:
    metadata:
      labels:
        app: {{ .Release.Name }}
    spec:
      containers:
      - name: {{ .Release.Name }}-container
        image: "{{ .Values.image.repository }}:{{ .Values.image.tag }}"
        ports:
        - containerPort: {{ .Values.service.port }}

In this example, placeholders like {{ .Release.Name }} and {{ .Values.image.tag }} will be filled with real values when we install the chart. This gives us a complete Kubernetes deployment manifest.

Helm charts make the deployment process much easier. They help us manage complex applications in Kubernetes by hiding the difficult configurations and encouraging us to reuse templates.

How Can We Create a Custom Helm Chart for Our Application?

Creating a custom Helm chart for our application involves some steps. This helps us package our Kubernetes resources and manage their deployment easily. Here is a simple guide to creating a custom Helm chart.

Step 1: Install Helm

First, we need to make sure that Helm is installed on our local machine. We can check this by running:

helm version

If Helm is not installed, we can follow the instructions from the official Helm installation guide.

Step 2: Create a New Helm Chart

Next, we use the Helm CLI to create a new chart. We will change my-application to our chosen chart name:

helm create my-application

This command makes a directory structure like this:

my-application/
  ├── Chart.yaml
  ├── values.yaml
  ├── charts/
  ├── templates/
  │   ├── deployment.yaml
  │   ├── service.yaml
  │   ├── ingress.yaml
  │   └── ...

Step 3: Customize Chart.yaml

Now, we will edit the Chart.yaml file. This file helps us define information about our chart:

apiVersion: v2
name: my-application
description: A Helm chart for Kubernetes deployment
version: 0.1.0
appVersion: "1.0"

Step 4: Configure values.yaml

The values.yaml file has default values for our chart. We can define variables that will be used in our templates:

replicaCount: 2

image:
  repository: my-app-image
  tag: latest
  pullPolicy: IfNotPresent

service:
  type: ClusterIP
  port: 80

resources: {}

Step 5: Define Kubernetes Resources in Templates

In the templates/ directory, we edit or create YAML files to define Kubernetes resources. For example, we can change deployment.yaml:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: {{ .Release.Name }}-deployment
spec:
  replicas: {{ .Values.replicaCount }}
  selector:
    matchLabels:
      app: {{ .Release.Name }}
  template:
    metadata:
      labels:
        app: {{ .Release.Name }}
    spec:
      containers:
      - name: {{ .Release.Name }}
        image: "{{ .Values.image.repository }}:{{ .Values.image.tag }}"
        ports:
        - containerPort: 80
        resources:
          {{- toYaml .Values.resources | nindent 12 }}

Step 6: Install the Chart

To deploy our custom chart to a Kubernetes cluster, we use:

helm install my-release ./my-application

We will change my-release to our desired release name.

Step 7: Upgrade and Manage the Chart

When we want to update our application, we can change the chart files and run:

helm upgrade my-release ./my-application

Step 8: Package the Chart (Optional)

If we want to share our chart, we can package it:

helm package my-application

This will create a .tgz file that we can share or upload to a chart repository.

By following these steps, we can create a custom Helm chart for our application. This helps us manage deployments easily on Kubernetes. For more details on Helm, we can check the Helm charts documentation.

What Are the Best Practices for Structuring Helm Charts?

When we structure Helm charts for deploying complex apps on Kubernetes, following best practices is very important. This helps with maintainability, scalability, and ease of use. Here are some good practices we can follow:

  1. Directory Structure: We should follow a standard directory structure in our Helm chart. This keeps everything organized. A typical structure looks like this:

    mychart/
├── .helmignore
├── Chart.yaml
├── values.yaml
├── charts/
├── templates/
│   ├── deployment.yaml
│   ├── service.yaml
│   └── _helpers.tpl

  2. Chart.yaml: We need to define the metadata of our Helm chart. This includes the name, version, and dependencies. For example:

    apiVersion: v2
name: mychart
description: A Helm chart for Kubernetes
version: 0.1.0
dependencies:
  - name: redis
    version: 14.0.0
    repository: https://charts.bitnami.com/bitnami

  3. values.yaml: We can use a values file to set default configurations for our templates. This helps with easy customization during installation. For example:

    replicaCount: 3
image:
  repository: myapp
  tag: latest
service:
  type: ClusterIP
  port: 8080

  4. Templates Directory: We should keep our Kubernetes manifests in the templates/ directory. Use Go templating syntax to make our templates dynamic. For example, in deployment.yaml:

    apiVersion: apps/v1
kind: Deployment
metadata:
  name: {{ .Release.Name }}-deployment
spec:
  replicas: {{ .Values.replicaCount }}
  selector:
    matchLabels:
      app: {{ .Release.Name }}
  template:
    metadata:
      labels:
        app: {{ .Release.Name }}
    spec:
      containers:
        - name: {{ .Release.Name }}
          image: "{{ .Values.image.repository }}:{{ .Values.image.tag }}"
          ports:
            - containerPort: 8080

  5. **Use _helpers.tpl**: We can store reusable templates in _helpers.tpl to avoid repeating ourselves. For example, we can define a common label:

    {{/*
Common label template
*/}}
{{- define "mychart.labels" -}}
app: {{ .Release.Name }}
{{- end -}}

  6. Versioning: We should use semantic versioning for our Helm charts. This helps us keep compatibility and track changes. We need to update the version and appVersion fields in Chart.yaml as needed.

  7. Testing: We can add tests in our charts using the tests directory. This makes sure our app works as expected when deployed. For example:

    mychart/
├── tests/
│   └── test-connection.yaml

  8. Documentation: It is good to provide clear documentation in our charts. This includes usage instructions, configuration options, and examples. We can put this in a README.md file.

  9. Linting: We can use helm lint to check our chart for common problems. This helps ensure it follows best practices.

  10. Resource Management: We should define resource requests and limits in our templates. This helps manage resource allocation well:

    resources:
  requests:
    memory: "64Mi"
    cpu: "250m"
  limits:
    memory: "128Mi"
    cpu: "500m"

By following these best practices for structuring Helm charts, we can make sure our deployments are organized, efficient, and easy to manage in a Kubernetes environment. This structured approach helps our team understand things better. It also makes future updates and maintenance simpler. For more detailed info on creating and managing Helm charts, you can check this guide.

How Do We Manage Configurations and Secrets with Helm?

We can manage configurations and secrets in Helm using values.yaml, ConfigMaps, and Kubernetes Secrets. Let’s see how we can handle both configurations and secrets in our Helm charts.

Using values.yaml

The values.yaml file in a Helm chart lets us set default configuration values for our application. We can change these values when we deploy the app. We do this by giving our own values.yaml file or using the --set flag.

Here is an example of a values.yaml file:

replicaCount: 3
image:
  repository: my-app
  tag: latest
service:
  type: ClusterIP
  port: 80

If we want to change values during installation, we can do it like this:

helm install my-release my-chart -f custom-values.yaml

Or we can use the --set flag like this:

helm install my-release my-chart --set image.tag=v1.0.0

Managing Secrets

For sensitive data like passwords or API keys, we should use Kubernetes Secrets. Helm can create and manage these secrets for us.

  1. Create a Secret in the Chart: We need to define a secret in our Helm chart templates.
apiVersion: v1
kind: Secret
metadata:
  name: my-secret
type: Opaque
data:
  password: {{ .Values.secret.password | b64enc | quote }}
  1. Reference the Secret in Our Deployment:

In our deployment template, we can reference the secret as an environment variable:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: my-app
spec:
  replicas: {{ .Values.replicaCount }}
  template:
    spec:
      containers:
      - name: my-app
        image: {{ .Values.image.repository }}:{{ .Values.image.tag }}
        env:
        - name: APP_PASSWORD
          valueFrom:
            secretKeyRef:
              name: my-secret
              key: password

Using ConfigMaps

For non-sensitive configuration data, we can use ConfigMaps. We define a ConfigMap in our Helm chart and reference it in our application.

  1. Create a ConfigMap:
apiVersion: v1
kind: ConfigMap
metadata:
  name: my-config
data:
  config.json: |
    {
      "key": "{{ .Values.config.key }}"
    }
  1. Mount the ConfigMap in Our Deployment:
apiVersion: apps/v1
kind: Deployment
metadata:
  name: my-app
spec:
  replicas: {{ .Values.replicaCount }}
  template:
    spec:
      containers:
      - name: my-app
        image: {{ .Values.image.repository }}:{{ .Values.image.tag }}
        volumeMounts:
        - name: config-volume
          mountPath: /app/config
      volumes:
      - name: config-volume
        configMap:
          name: my-config

Best Practices

  • Use helm secrets: For managing secrets, we can use the helm-secrets plugin. This plugin helps to encrypt our secrets files using tools like SOPS.
  • Separate Sensitive and Non-Sensitive Data: We should keep configurations and secrets in different files. This makes managing them easier.
  • Template Functions: We can use Helm template functions to change values, like encoding or formatting configurations as needed.

By following these methods, we can manage configurations and secrets in our Kubernetes applications using Helm.

What Are Real-World Use Cases for Using Helm in Kubernetes?

Helm is a great tool. It helps us to deploy and manage applications in Kubernetes. Here are some real-world cases where we can use Helm in Kubernetes:

  1. Microservices Deployment: With Helm, we can package microservices into charts. This makes it simple to manage dependencies and versions. For example, when we deploy a microservices setup, we can define each service as a Helm chart. This way, we can deploy all services at once using one command:

    helm install my-microservices ./my-chart

  2. Continuous Integration/Continuous Deployment (CI/CD): Helm works well with CI/CD pipelines. Using Helm charts helps us automate the deployment process. This lets developers focus on writing code without stressing about deployment. For example, a CI/CD pipeline can start a Helm upgrade when we merge code:

    helm upgrade my-app ./my-chart --install

  3. Environment Management: Helm helps us manage different environments like development, staging, and production using the same Helm chart. We can use specific values files for each environment. This way, we can customize deployments without making new chart definitions. We can do this by:

    helm install my-app ./my-chart -f values-prod.yaml

  4. Application Rollbacks: Helm has versioning built-in. This makes it easy to go back to previous versions if something goes wrong during deployment. This is very important in production because we need to keep our services running. To rollback to the last version, we can use:

    helm rollback my-app 1

  5. Managing Configurations and Secrets: Helm can manage configurations and secrets well with ConfigMaps and Secrets. When we define these in our Helm charts, we make sure sensitive information is safe while keeping flexibility in deployments. Here is an example of defining a Secret in a Helm chart:

    apiVersion: v1
kind: Secret
metadata:
  name: my-secret
type: Opaque
data:
  password: {{ .Values.secret.password | b64enc | quote }}

  6. Multi-Cloud Deployments: Helm allows us to deploy consistently across different cloud providers. By defining our applications and their needs in Helm charts, we can use the same deployment scripts no matter the infrastructure, like AWS, GCP, or Azure.

  7. Community Charts: Helm has a big collection of community charts. We can use these charts to quickly deploy complex applications. For example, we can deploy a popular app like WordPress with just one Helm command:

    helm repo add bitnami https://charts.bitnami.com/bitnami
helm install my-wordpress bitnami/wordpress

  8. Custom Application Deployment: For companies with unique applications, we can create custom Helm charts. This allows us to have deployments that fit our special needs. We can define resource limits, affinity rules, and more in the values.yaml file to match what we need.

By using Helm in these real situations, we can make our Kubernetes deployments more efficient, reliable, and scalable. If you want to learn more about using Helm for complex applications, you can check out how to create and manage Helm charts.

How Do I Upgrade and Rollback Applications with Helm?

Upgrading and rolling back applications with Helm is simple. It needs just a few commands. Helm keeps track of release history. This means we can go back to an earlier version if we need.

Upgrading Applications

To upgrade an application, we use the helm upgrade command. The basic format is:

helm upgrade [RELEASE_NAME] [CHART] [flags]

For example, if we want to upgrade a release called my-app with a chart found at ./my-app-chart, we run:

helm upgrade my-app ./my-app-chart

We can also add extra settings with the --set flag or use a values file:

helm upgrade my-app ./my-app-chart --set image.tag=newtag

OR

helm upgrade my-app ./my-app-chart -f custom-values.yaml

Rollback Applications

If an upgrade does not work or makes problems, we can roll back to a previous version. We use the helm rollback command. The format is:

helm rollback [RELEASE_NAME] [REVISION]

To roll back the my-app release to revision 1, we run:

helm rollback my-app 1

We can see the history of our releases and their revisions with:

helm history my-app

This command shows us the list of revisions, their statuses, and the time they were deployed. This helps us choose the right version to roll back.

Best Practices

  • Always test upgrades in a staging area before moving to production.
  • Use version tags for your images and charts. This helps manage upgrades and rollbacks better.
  • Keep notes on your Helm releases and their settings. This makes troubleshooting easier.

For more info on managing Helm charts and deployments, check how to create and manage Helm charts.

Frequently Asked Questions

What is Helm and how does it simplify Kubernetes deployments?

Helm is a tool for managing packages in Kubernetes. It makes it easier to deploy complex applications. Helm uses charts. Charts are like templates for Kubernetes resources. They help us deploy applications quickly and in a consistent way. With Helm, we can handle dependencies and versions easily. This helps us manage our applications better on Kubernetes. So, Helm is an important tool for working with Kubernetes.

How do I create a Helm chart for my application?

To create a Helm chart, we need to organize our Kubernetes files in a way that Helm understands. First, we run helm create <chart-name>. This will create a basic setup for our chart. Next, we can change the files that Helm creates. We should edit values.yaml for the default settings. We also need to set up templates for our Kubernetes resources like Deployments and Services. If you want to learn more about creating Helm charts, check our guide on how do I create and manage Helm charts.

What are the best practices for structuring Helm charts?

To structure Helm charts well, we should keep them organized based on their purpose. We should use clear names and have a good values.yaml for configuration. It is also good to use subcharts for more complex applications. We should make sure our charts are version controlled. This helps us work together and keeps everything easy to manage. This way, we can deploy and manage applications on Kubernetes better.

How can I manage configurations and secrets using Helm?

We can manage configurations and secrets in Helm by using values.yaml files for settings and Kubernetes Secrets for sensitive information. We can set placeholder values in our templates. Then, we can change them when we deploy using the --set flag or by using a custom values.yaml. For keeping sensitive information safe, we should use Kubernetes Secrets. Helm works well with these secrets during deployments.

How do I upgrade or rollback applications using Helm?

Upgrading or rolling back applications with Helm is simple. To upgrade, we run helm upgrade <release-name> <chart-path>, and we can add any new settings we want. If we need to go back to a previous version, we use helm rollback <release-name> <revision-number>. Helm keeps track of versions, so it is easy to go back to a stable version if we need to. This helps us keep our applications running with little downtime on Kubernetes.

These FAQs give us important information about using Helm for deploying complex applications in Kubernetes. They help us improve our development and operational tasks. For more details, look at our article on what is Helm and how does it help with Kubernetes deployments.