Integrate with Kubernetes Deployment using Helm

Applications hosted in Kubernetes can access data in App Configuration using the App Configuration provider library. The App Configuration provider has built-in caching and refreshing capabilities so applications can have dynamic configuration without redeployment. If you prefer not to update your application, this tutorial shows how to bring data from App Configuration to your Kubernetes using Helm via deployment. This way, your application can continue accessing configuration from Kubernetes variables and secrets. You run Helm upgrade when you want your application to pick up new configuration changes.

Helm provides a way to define, install, and upgrade applications running in Kubernetes. A Helm chart contains the information necessary to create an instance of a Kubernetes application. Configuration is stored outside of the chart itself, in a file called values.yaml.

During the release process, Helm merges the chart with the proper configuration to run the application. For example, variables defined in values.yaml can be referenced as environment variables inside the running containers. Helm also supports creation of Kubernetes Secrets, which can be mounted as data volumes or exposed as environment variables.

You can override the values stored in values.yaml by providing additional YAML-based configuration files on the command line when running Helm. Azure App Configuration supports exporting configuration values to YAML files. Integrating this export capability into your deployment allows your Kubernetes applications to leverage configuration values stored in App Configuration.

In this tutorial, you learn how to:

  • Use values from App Configuration when deploying an application to Kubernetes using Helm.
  • Create a Kubernetes Secret based on a Key Vault reference in App Configuration.

This tutorial assumes basic understanding of managing Kubernetes with Helm. Learn more about installing applications with Helm in Azure Kubernetes Service.

Prerequisites

Create an App Configuration store

  1. To create a new App Configuration store, sign in to the Azure portal.

  2. In the upper-left corner of the home page, select Create a resource.

  3. In the Search services and marketplace box, enter App Configuration and select Enter.

    Screenshot that shows the Search for App Configuration page.

  4. Select App Configuration from the search results, and then select Create.

    Screenshot that shows the Create page.

  5. On the Create App Configuration pane, enter the following settings:

    Setting Suggested value Description
    Subscription Your subscription Select the Azure subscription that you want to use to test App Configuration. If your account has only one subscription, it's automatically selected and the Subscription list isn't displayed.
    Resource group AppConfigTestResources Select or create a resource group for your App Configuration store resource. This group is useful for organizing multiple resources that you might want to delete at the same time by deleting the resource group. For more information, see Use resource groups to manage your Azure resources.
    Resource name Globally unique name Enter a unique resource name to use for the App Configuration store resource. The name must be a string between 5 and 50 characters and contain only numbers, letters, and the - character. The name can't start or end with the - character.
    Location Central US Use Location to specify the geographic location in which your app configuration store is hosted. For the best performance, create the resource in the same region as other components of your application.
    Pricing tier Free Select the desired pricing tier. For more information, see the App Configuration pricing page.
  6. Select Review + create to validate your settings.

  7. Select Create. The deployment might take a few minutes.

  8. After the deployment finishes, go to the App Configuration resource. Select Settings > Access keys. Make a note of the primary read-only key connection string. You'll use this connection string later to configure your application to communicate with the App Configuration store that you created.

  1. Select Configuration Explorer > Create to add the following key-value pairs:

    Key Value
    settings.color White
    settings.message Data from Azure App Configuration
  2. Leave Label and Content Type empty for now.

Add a Key Vault reference to App Configuration

  1. Sign in to the Azure portal and add a secret to Key Vault with name Password and value myPassword.

  2. Select the App Configuration store instance that you created in previous section.

  3. Select Configuration Explorer.

  4. Select + Create > Key vault reference, and then specify the following values:

    • Key: Select secrets.password.
    • Label: Leave this value blank.
    • Subscription, Resource group, and Key vault: Enter the values corresponding to those in the key vault you created in previous step.
    • Secret: Select the secret named Password that you created in the previous section.

Create Helm chart

First, create a sample Helm chart with the following command:

helm create mychart

Helm creates a new directory called mychart with the structure shown below.

Tip

Follow this charts guide to learn more.

mychart
|-- Chart.yaml
|-- charts
|-- templates
|   |-- NOTES.txt
|   |-- _helpers.tpl
|   |-- deployment.yaml
|   |-- ingress.yaml
|   `-- service.yaml
`-- values.yaml

Next, update the spec:template:spec:containers section of the deployment.yaml file. The following snippet adds two environment variables to the container. You'll set their values dynamically at deployment time.

env:
- name: Color
    value: {{ .Values.settings.color }}
- name: Message
    value: {{ .Values.settings.message }}

The complete deployment.yaml file after the update should look like below.

apiVersion: apps/v1beta2
kind: Deployment
metadata:
  name: {{ include "mychart.fullname" . }}
  labels:
    app.kubernetes.io/name: {{ include "mychart.name" . }}
    helm.sh/chart: {{ include "mychart.chart" . }}
    app.kubernetes.io/instance: {{ .Release.Name }}
    app.kubernetes.io/managed-by: {{ .Release.Service }}
spec:
  replicas: {{ .Values.replicaCount }}
  selector:
    matchLabels:
      app.kubernetes.io/name: {{ include "mychart.name" . }}
      app.kubernetes.io/instance: {{ .Release.Name }}
  template:
    metadata:
      labels:
        app.kubernetes.io/name: {{ include "mychart.name" . }}
        app.kubernetes.io/instance: {{ .Release.Name }}
    spec:
      containers:
        - name: {{ .Chart.Name }}
          image: "{{ .Values.image.repository }}:{{ .Values.image.tag }}"
          imagePullPolicy: {{ .Values.image.pullPolicy }}
          env:
            - name: Color
              value: {{ .Values.settings.color }}
            - name: Message
              value: {{ .Values.settings.message }}
          ports:
            - name: http
              containerPort: 80
              protocol: TCP
          livenessProbe:
            httpGet:
              path: /
              port: http
          readinessProbe:
            httpGet:
              path: /
              port: http
          resources:
{{ toYaml .Values.resources | indent 12 }}
    {{- with .Values.nodeSelector }}
      nodeSelector:
{{ toYaml . | indent 8 }}
    {{- end }}
    {{- with .Values.affinity }}
      affinity:
{{ toYaml . | indent 8 }}
    {{- end }}
    {{- with .Values.tolerations }}
      tolerations:
{{ toYaml . | indent 8 }}
    {{- end }}

To store sensitive data as Kubernetes Secrets, add a secrets.yaml file under the templates folder.

Tip

Learn more about how to use Kubernetes Secrets.

apiVersion: v1
kind: Secret
metadata:
  name: mysecret
type: Opaque
data:
  password: {{ .Values.secrets.password | b64enc }}

Finally, update the values.yaml file with the following content to optionally provide default values of the configuration settings and secrets that referenced in the deployment.yaml and secrets.yaml files. Their actual values will be overwritten by configuration pulled from App Configuration.

# settings will be overwritten by App Configuration
settings:
  color: red
  message: myMessage

Pass configuration from App Configuration in Helm install

First, download the configuration from App Configuration to a myConfig.yaml file. Use a key filter to only download those keys that start with settings.. If in your case the key filter is not sufficient to exclude keys of Key Vault references, you may use the argument --skip-keyvault to exclude them.

Tip

Learn more about the export command.

az appconfig kv export -n myAppConfiguration -d file --path myConfig.yaml --key "settings.*"  --separator "." --format yaml

Next, download secrets to a file called mySecrets.yaml. The command-line argument --resolve-keyvault resolves the Key Vault references by retrieving the actual values in Key Vault. You'll need to run this command with credentials that have access permissions to the corresponding Key Vault.

Warning

As this file contains sensitive information, keep the file with care and clean up when it's not needed anymore.

az appconfig kv export -n myAppConfiguration -d file --path mySecrets.yaml --key "secrets.*" --separator "." --resolve-keyvault --format yaml

Use helm upgrade's -f argument to pass in the two configuration files you've created. They'll override the configuration values defined in values.yaml with the values exported from App Configuration.

helm upgrade --install -f myConfig.yaml -f mySecrets.yaml "example" ./mychart

You can also use the --set argument for helm upgrade to pass literal key values. Using the --set argument is a good way to avoid persisting sensitive data to disk.

$secrets = az appconfig kv list -n myAppConfiguration --key "secrets.*" --resolve-keyvault --query "[*].{name:key, value:value}" | ConvertFrom-Json

foreach ($secret in $secrets) {
  $keyvalues += $secret.name + "=" + $secret.value + ","
}

if ($keyvalues){
  $keyvalues = $keyvalues.TrimEnd(',')
  helm upgrade --install --set $keyvalues "example" ./mychart
}
else{
  helm upgrade --install "example" ./mychart
}

Verify that configurations and secrets were set successfully by accessing the Kubernetes Dashboard. You'll see that the color and message values from App Configuration were populated into the container's environment variables.

Quickstart app launch local

One secret, password, stores as Key Vault reference in App Configuration was also added into Kubernetes Secrets.

Screenshot that highlights the password in the Data section.

Clean up resources

If you don't want to continue using the resources created in this article, delete the resource group you created here to avoid charges.

Important

Deleting a resource group is irreversible. The resource group and all the resources in it are permanently deleted. Ensure that you don't accidentally delete the wrong resource group or resources. If you created the resources for this article inside a resource group that contains other resources you want to keep, delete each resource individually from its respective pane instead of deleting the resource group.

  1. Sign in to the Azure portal, and select Resource groups.
  2. In the Filter by name box, enter the name of your resource group.
  3. In the result list, select the resource group name to see an overview.
  4. Select Delete resource group.
  5. You're asked to confirm the deletion of the resource group. Enter the name of your resource group to confirm, and select Delete.

After a few moments, the resource group and all its resources are deleted.

Next steps

In this tutorial, you exported Azure App Configuration data to be used in a Kubernetes deployment with Helm. To learn more about how to use App Configuration, continue to the Azure CLI samples.