bitnamicharts/external-dns repository overview

⁠Bitnami Secure Images Helm chart for ExternalDNS

ExternalDNS is a Kubernetes addon that configures public DNS servers with information about exposed Kubernetes services to make them discoverable.

Overview of ExternalDNS⁠

Trademarks: This software listing is packaged by Bitnami. The respective trademarks mentioned in the offering are owned by the respective companies, and use of them does not imply any affiliation or endorsement.

⁠ TL;DR

helm install my-release oci://REGISTRY_NAME/REPOSITORY_NAME/external-dns

⁠ Introduction

This chart bootstraps a ExternalDNS⁠ deployment on a Kubernetes⁠ cluster using the Helm⁠ package manager.

⁠ Before you begin

• Kubernetes 1.23+
• Helm 3.8.0+

⁠ Installing the Chart

To install the chart with the release name my-release:

helm install my-release oci://REGISTRY_NAME/REPOSITORY_NAME/external-dns

The command deploys ExternalDNS on the Kubernetes cluster in the default configuration. The Parameters⁠ section lists the parameters that can be configured during installation.

⁠ Configuration and installation details

This section describes credentials, configuration, and other installation options.

⁠ Resource requests and limits

Bitnami charts allow setting resource requests and limits for all containers inside the chart deployment. These are inside the resources value (check parameter table). Setting requests is essential for production workloads and these should be adapted to your specific use case.

To make this process easier, the chart contains the resourcesPreset values, which automatically sets the resources section according to different presets. Check these presets in the bitnami/common chart⁠. However, in production workloads using resourcesPreset is discouraged as it may not fully adapt to your specific needs. Find more information on container resource management in the official Kubernetes documentation⁠.

⁠ Rolling VS Immutable tags⁠

It is strongly recommended to use immutable tags in a production environment. This ensures your deployment does not change automatically if the same tag is updated with a different image.

Bitnami will release a new chart updating its containers if a new version of the main container, significant changes, or critical vulnerabilities exist.

⁠ Prometheus metrics

This chart can be integrated with Prometheus by setting metrics.enabled to true. This will expose external-dns native Prometheus endpoint in the service. It will have the necessary annotations to be automatically scraped by Prometheus.

⁠Prometheus requirements

It is necessary to have a working installation of Prometheus or Prometheus Operator for the integration to work. Install the Bitnami Prometheus helm chart⁠ or the Bitnami Kube Prometheus helm chart⁠ to easily have a working Prometheus in your cluster.

⁠Integration with Prometheus Operator

The chart can deploy ServiceMonitor objects for integration with Prometheus Operator installations. To do so, set the value metrics.serviceMonitor.enabled=true. Ensure that the Prometheus Operator CustomResourceDefinitions are installed in the cluster or it will fail with the following error:

no matches for kind "ServiceMonitor" in version "monitoring.coreos.com/v1"

Install the Bitnami Kube Prometheus helm chart⁠ for having the necessary CRDs and the Prometheus Operator.

⁠ Backup and restore

To back up and restore Helm chart deployments on Kubernetes, you need to back up the persistent volumes from the source deployment and attach them to a new deployment using Velero⁠, a Kubernetes backup/restore tool. Find the instructions for using Velero in this guide⁠.

⁠ Setting Pod's affinity

This chart allows you to set your custom affinity using the affinity parameter. Find more information about Pod's affinity in the kubernetes documentation⁠.

As an alternative, you can use of the preset configurations for pod affinity, pod anti-affinity, and node affinity available at the bitnami/common⁠ chart. To do so, set the podAffinityPreset, podAntiAffinityPreset, or nodeAffinityPreset parameters.

⁠ Using IRSA

If you are deploying to AWS EKS and you want to leverage IRSA⁠. You will need to override fsGroup and runAsUser with 65534(nfsnobody) and 0 respectively. Otherwise service account token will not be properly mounted. You can use the following arguments:

--set podSecurityContext.fsGroup=65534 --set podSecurityContext.runAsUser=0

⁠ Webhook Providers

Webhook providers allow integrating ExternalDNS with DNS providers through an HTTP interface. This approach decouples ExternalDNS and the Providers code which can be running in separate processes.

With the Bitnami ExternalDNS chart, you can deploy Webhook Providers and configure ExternalDNS easily using sidecars and extraArgs values:

provider: webhook

extraArgs:
  webhook-provider-url: http://localhost:8080
  txt-prefix: reg-

sidecars:
  - name: my-webhook
    image: <external-dns-webhook-image>
    ports:
      - containerPort: 8080
        name: http
    livenessProbe:
      httpGet:
        path: /
        port: http
      initialDelaySeconds: 10
      timeoutSeconds: 5
    readinessProbe:
      tcpSocket:
        port: http
      initialDelaySeconds: 10
      timeoutSeconds: 5
    env:
      - name: <WEBHOOK-CONFIG-ENV-VAR>
        value: TEST
      ...

More information about these new providers can be found in the ExternalDNS documentation⁠

⁠ FIPS parameters

The FIPS parameters only have effect if you are using images from the Bitnami Secure Images catalog⁠.

For more information on this new support, please refer to the FIPS Compliance section⁠.

⁠ Tutorials

Find information about the requirements for each DNS provider on the link below:

• ExternalDNS Tutorials⁠

For instance, to install ExternalDNS on AWS, you need to:

• Provide the K8s worker node which runs the cluster autoscaler with a minimum IAM policy (check IAM permissions docs⁠ for more information).
• Setup a hosted zone on Route53 and annotate the Hosted Zone ID and its associated "nameservers" as described on these docs⁠.
• Install ExternalDNS chart using the command below:

helm install my-release \
  --set provider=aws \
  --set aws.zoneType=public \
  --set txtOwnerId=HOSTED_ZONE_IDENTIFIER \
  --set domainFilters[0]=HOSTED_ZONE_NAME \
  oci://REGISTRY_NAME/REPOSITORY_NAME/external-dns

⁠ Parameters

The following subsections list global, common, and component-specific parameters.

⁠ Global parameters

⁠ Common parameters

⁠ external-dns parameters

Note: the README for this chart is longer than the DockerHub length limit of 25000, so it has been trimmed. The full README can be found at https://techdocs.broadcom.com/us/en/vmware-tanzu/bitnami-secure-images/bitnami-secure-images/services/bsi-app-doc/apps-charts-external-dns-index.html⁠