ExternalDNS Webhook Provider for Simply.com

April 5, 2026 · View on GitHub

A webhook provider for ExternalDNS that enables automatic DNS record management in Simply.com.

Overview

This webhook adapter allows ExternalDNS to manage DNS records in Simply.com via their public REST API. ExternalDNS automatically creates, updates, and deletes DNS records based on Kubernetes resources like Services and Ingresses.

Features

Full support for ExternalDNS webhook interface
Manages A, CNAME, TXT, and other DNS record types
Handles record creation, updates, and deletions
Supports TTL management
Domain filtering support
Kubernetes-native deployment

Prerequisites

Kubernetes cluster (1.19+)
ExternalDNS (v0.14.0+)
Simply.com account with API access
Simply.com API key

Installation

1. Get Simply.com Credentials

Log in to your Simply.com account
Navigate to API settings
Get your account name and API key

2. Deploy the Webhook

Using Helm

kubectl create namespace external-dns

kubectl create secret generic simply-credentials \
  --from-literal=account-name='YOUR_ACCOUNT_NAME' \
  --from-literal=api-key='YOUR_API_KEY' \
  -n external-dns

helm install external-dns-simply \
  oci://ghcr.io/uozalp/helm/external-dns-simply \
  -n external-dns \
  --set domainFilter=example.com

Then install ExternalDNS separately (e.g. via the official Helm chart) and point it to the webhook:

helm repo add external-dns https://kubernetes-sigs.github.io/external-dns/

helm install external-dns external-dns/external-dns \
  -n external-dns \
  --set provider.name=webhook \
  --set "extraArgs[0]=--webhook-provider-url=http://external-dns-simply.external-dns.svc.cluster.local:8888"

Using kubectl

# Clone the repository
git clone https://github.com/uozalp/external-dns-simply-webhook.git
cd external-dns-simply-webhook

# Create namespace
kubectl create namespace external-dns

# Create secret with your Simply.com credentials
kubectl create secret generic simply-credentials \
  --from-literal=account-name='YOUR_ACCOUNT_NAME' \
  --from-literal=api-key='YOUR_API_KEY' \
  -n external-dns

# Deploy the webhook
kubectl apply -f deploy/deployment.yaml

# Deploy ExternalDNS
kubectl apply -f deploy/external-dns.yaml

Note: You can optionally edit deploy/deployment.yaml and deploy/external-dns.yaml to set specific domain(s) in the DOMAIN_FILTER and --domain-filter settings. If not set, all domains managed by Simply.com will be used.

3. Configure ExternalDNS

The webhook is configured via environment variables in the deployment:

Variable	Description	Required	Default
`SIMPLY_ACCOUNT_NAME`	Simply.com account name	Yes	-
`SIMPLY_API_KEY`	Simply.com API key	Yes	-
`DOMAIN_FILTER`	Comma-separated list of domains to manage	No	All domains
`LOG_LEVEL`	Logging level (debug, info, warn, error)	No	`info`
`PORT`	HTTP server port	No	`8888`

ExternalDNS configuration:

args:
  - --source=service              # Watch Services
  - --source=ingress              # Watch Ingresses
  - --domain-filter=example.com   # Only manage this domain
  - --provider=webhook
  - --webhook-provider-url=http://external-dns-simply-webhook.external-dns.svc.cluster.local:8888
  - --policy=upsert-only          # Don't delete records (or use 'sync')
  - --registry=txt                # Use TXT registry for ownership
  - --txt-owner-id=my-cluster-id  # Unique identifier for this cluster
  - --interval=1m                 # Sync interval

API Endpoints

The webhook exposes the following endpoints:

Method	Path	Description
GET	`/records`	Returns current DNS records
POST	`/records`	Applies DNS record changes
POST	`/adjustendpoints`	Normalizes endpoints (optional)
GET	`/healthz`	Health check endpoint

All endpoints use Content-Type: application/external.dns.webhook+json;version=1

Development

Prerequisites

Go 1.21+
Docker (for building images)
kubectl (for testing)

Build

# Install dependencies
make deps

# Build binary
make build

# Run locally
export SIMPLY_ACCOUNT_NAME='your-account-name'
export SIMPLY_API_KEY='your-api-key'
export DOMAIN_FILTER='example.com'
make run

Test

# Run tests
make test

# Format code
make fmt

# Lint code
make lint

Build Docker Image

# Build image
make docker-build VERSION=v1.0.0

# Push image
make docker-push VERSION=v1.0.0

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.

License

This project is licensed under the Apache License 2.0 - see the LICENSE file for details.

Acknowledgments

ExternalDNS - Kubernetes DNS automation
Simply.com - DNS provider

Support

For issues and questions:

Open an issue on GitHub
Check ExternalDNS documentation: https://kubernetes-sigs.github.io/external-dns/