Cert-Manager webhook for CoreDNS

Cert-Manager dns01 webhook for CoreDNS using ETCD plugin.
See https://cert-manager.io/docs/configuration/acme/dns01/webhook/ for more information.

Usage

1. Create a secret containing your etcd credentials in the same namespace than the webhook

kubectl create secret generic etcd-credentials \
  --from-literal=etcd-username='ETCD-USERNAME' \
  --from-literal=etcd-password='ETCD-PASSWORD' \
  -n cert-manager

2. Create RBAC configuration to access secret

apiVersion: rbac.authorization.k8s.io/v1
kind: Role
metadata:
  name: cert-manager-webhook-coredns:secret-reader
  namespace: cert-manager
rules:
- apiGroups: [""]
  resources: ["secrets"]
  resourceNames: ["etcd-credentials"]
  verbs: ["get", "watch"]
---
apiVersion: rbac.authorization.k8s.io/v1
kind: RoleBinding
metadata:
  name: cert-manager-webhook-coredns:secret-reader
  namespace: cert-manager
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: Role
  name: cert-manager-webhook-coredns:secret-reader
subjects:
- apiGroup: ""
  kind: ServiceAccount
  name: cert-manager-webhook-coredns

3. Create a ClusterIssuer or Issuer

apiVersion: cert-manager.io/v1
kind: ClusterIssuer
metadata:
  name: nxthdr-acme
spec:
  acme:
    email: admin@nxthdr.dev
    server: https://acme-v02.api.letsencrypt.org/directory
    privateKeySecretRef:
      name: nxthdr-acme
    solvers:
    - dns01:
        webhook:
          groupName: acme.nxthdr.dev
          solverName: coredns-solver
          config:
            coreDNSPrefix: /skydns
            etcdEndpoints: "http://[2a06:de00:50:1:ff00::11]:2379"
            etcdUsernameRef:
              name: etcd-credentials
              key: etcd-username        
            etcdPasswordRef: 
              name: etcd-credentials
              key: etcd-password

4. Finally, install the Cert-Manager webhook for CoreDNS. Choose a unique group name to identify your company or organization (for example acme.mycompany.example). In this example it is installed in the cert-manager namespace.

helm upgrade --install \
  cert-manager-webhook-coredns \
  -n cert-manager \
  --set groupName='<YOUR_UNIQUE_GROUP_NAME>' \
  deploy/cert-manager-webhook-coredns/

Running the test suite

All DNS providers must run the DNS01 provider conformance testing suite, else they will have undetermined behaviour when used with cert-manager.

It is essential that you configure and run the test suite when creating a DNS01 webhook.

An example Go test file has been provided in main_test.go.

Before you can run the test suite, you need to duplicate the .sample files in testdata/coredns-solver/ and update the configuration with the appropriate ETCD credentials.

You can run the test suite with:

$ TEST_ZONE_NAME=example.com. make test

The example file has a number of areas you must fill in and replace with your own options in order for tests to pass.