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ExternalDNS - GleSYS Webhook

⚠️ NOTE: his Webhook was forked and modified from the IONOS Webhook to work with GleSYS: https://github.com/ionos-cloud/external-dns-ionos-webhook

ExternalDNS is a Kubernetes add-on for automatically managing Domain Name System (DNS) records for Kubernetes services by using different DNS providers. By default, Kubernetes manages DNS records internally, but ExternalDNS takes this functionality a step further by delegating the management of DNS records to an external DNS provider such as GleSYS. Therefore, the GleSYS webhook allows to manage your GleSYS domains inside your kubernetes cluster with ExternalDNS.

To use ExternalDNS with GleSYS, you need a GleSYS API key with permissions to create and modify DNS records.

Deployment in Kubernetes

secret.yml

---
apiVersion: v1
kind: Secret
metadata:
  name: external-dns-glesys
stringData:
  project: "clxxxxxx"
  accesskey: "xxxxxxxxxxxxxxxxxxxxxx"

$ kubectl apply -f secret.yaml

external-dns-glesys.yaml

---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: external-dns
spec:
  replicas: 1
  strategy:
    type: Recreate
  selector:
    matchLabels:
      app: external-dns
  template:
    metadata:
      labels:
        app: external-dns
    spec:
      serviceAccountName: external-dns
      containers:
        - name: external-dns
          image: registry.k8s.io/external-dns/external-dns:v0.14.0
          args:
            - --source=service
            - --source=ingress
            - --provider=webhook

        - image: ghcr.io/glesys/external-dns-glesys:v0.0.2
          name: glesys-webhook
          ports:
            - containerPort: 8888
          env:
            - name: GLESYS_PROJECT
              valueFrom:
                secretKeyRef:
                  name: external-dns-glesys
                  key: project
            - name: GLESYS_ACCESS_KEY
              valueFrom:
                secretKeyRef:
                  name: external-dns-glesys
                  key: accesskey

---
apiVersion: v1
kind: ServiceAccount
metadata:
  name: external-dns
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
  name: external-dns
rules:
  - apiGroups: [""]
    resources: ["services","endpoints","pods"]
    verbs: ["get","watch","list"]
  - apiGroups: ["extensions","networking.k8s.io"]
    resources: ["ingresses"]
    verbs: ["get","watch","list"]
  - apiGroups: [""]
    resources: ["nodes"]
    verbs: ["list"]
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
  name: external-dns-viewer
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: ClusterRole
  name: external-dns
subjects:
  - kind: ServiceAccount
    name: external-dns
    namespace: default

$ kubectl apply -f external-dns-glesys.yaml

Example deployment using the external DNS:

---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx
spec:
  replicas: 1
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
        - image: nginx
          name: nginx
          ports:
            - containerPort: 80
---
apiVersion: v1
kind: Service
metadata:
  name: nginx
  annotations:
    external-dns.alpha.kubernetes.io/internal-hostname: nginxinternal.example.com.
    external-dns.alpha.kubernetes.io/hostname: nginx.example.com.

spec:
  selector:
    app: nginx
  type: LoadBalancer
  ports:
    - protocol: TCP
      port: 80
      targetPort: 80

Local deployment

export GLESYS_PROJECT=clxxxxxx
export GLESYS_ACCESS_KEY=xxxxxxxxxxxxxxxxxxxxxx
CGO_ENABLED=0 go build
./external-dns-glesys

# In another terminal
curl http://localhost:8888/records -H 'Accept: application/external.dns.webhook+json;version=1'
# Example response:
[
  {
    "dnsName": "nginx.internal",
    "targets": [
      "10.99.237.62"
    ],
    "recordType": "A",
    "recordTTL": 3600
  }
]

How To Contribute

Development happens at GitHub; any typical workflow using Pull Requests are welcome. In the same spirit, we use the GitHub issue tracker for all reports (regardless of the nature of the report, feature request, bugs, etc.).