ACME webhook for Gandi (cert-manager-webhook-gandi)

cert-manager-webhook-gandi is an ACME webhook for cert-manager. It provides an ACME (read: Let's Encrypt) webhook for cert-manager, which allows to use a DNS-01 challenge with Gandi. This allows to provide Let's Encrypt certificates to Kubernetes for service protocols other than HTTP and furthermore to request wildcard certificates. Internally it uses the Gandi LiveDNS API to communicate with Gandi.

Quoting the ACME DNS-01 challenge:

This challenge asks you to prove that you control the DNS for your domain name by putting a specific value in a TXT record under that domain name. It is harder to configure than HTTP-01, but can work in scenarios that HTTP-01 can’t. It also allows you to issue wildcard certificates. After Let’s Encrypt gives your ACME client a token, your client will create a TXT record derived from that token and your account key, and put that record at _acme-challenge.<YOUR_DOMAIN>. Then Let’s Encrypt will query the DNS system for that record. If it finds a match, you can proceed to issue a certificate!

Building

Build the container image cert-manager-webhook-gandi:latest:

make build

Image

Ready made images are hosted on Docker Hub (image tags). Use at your own risk:

bwolf/cert-manager-webhook-gandi

Release History

Refer to the CHANGELOG file.

Compatibility

This webhook has been tested with cert-manager v1.5.4 and Kubernetes v1.22.2 on amd64. In theory it should work on other hardware platforms as well but no steps have been taken to verify this. Please drop me a note if you had success.

Testing with Minikube

1. Build this webhook in Minikube:

    minikube start --memory=4G --more-options
    eval $(minikube docker-env)
    make build
    docker images | grep webhook
   

2. Install cert-manager with Helm:

    helm repo add jetstack https://charts.jetstack.io
   
    helm install cert-manager jetstack/cert-manager \
        --namespace cert-manager \
        --create-namespace \
        --set installCRDs=true \
        --version v1.5.4 \
        --set 'extraArgs={--dns01-recursive-nameservers=8.8.8.8:53\,1.1.1.1:53}'
   
    kubectl get pods --namespace cert-manager --watch
   

   Note: refer to Name servers in the official documentation according the extraArgs.

   Note: ensure that the custom CRDS of cert-manager match the major version of the cert-manager release by comparing the URL of the CRDS with the helm info of the charts app version:

        helm search repo jetstack
   

   Example output:

        NAME                    CHART VERSION   APP VERSION     DESCRIPTION
        jetstack/cert-manager   v1.5.4          v1.5.4          A Helm chart for cert-manager
   

   Check the state and ensure that all pods are running fine (watch out for any issues regarding the cert-manager-webhook- pod and its volume mounts):

        kubectl describe pods -n cert-manager | less
   

3. Create the secret to keep the Gandi API key in the cert-manager namespace:

    kubectl create secret generic gandi-credentials \
        --namespace cert-manager --from-literal=api-token='<GANDI-API-KEY>'
   

   The Secret must reside in the same namespace as cert-manager.

4. Deploy this webhook (add --dry-run to try it and --debug to inspect the rendered manifests; Set logLevel to 6 for verbose logs):

   The features.apiPriorityAndFairness argument must be removed or set to false for Kubernetes older than 1.20.

    helm install cert-manager-webhook-gandi \
        --namespace cert-manager \
        --set features.apiPriorityAndFairness=true \
        --set image.repository=cert-manager-webhook-gandi \
        --set image.tag=latest \
        --set logLevel=2 \
        ./deploy/cert-manager-webhook-gandi
   

   To deploy using the image from Docker Hub (for example using the 0.2.0 tag):

    helm install cert-manager-webhook-gandi \
        --namespace cert-manager \
        --set features.apiPriorityAndFairness=true \
        --set image.tag=0.2.0 \
        --set logLevel=2 \
        ./deploy/cert-manager-webhook-gandi
   

   To deploy using the Helm repository (for example using the v0.2.0 version):

    helm install cert-manager-webhook-gandi \
        --repo https://bwolf.github.io/cert-manager-webhook-gandi \
        --version v0.2.0 \
        --namespace cert-manager \
        --set features.apiPriorityAndFairness=true \
        --set logLevel=2
   

   Check the logs

        kubectl get pods -n cert-manager --watch
        kubectl logs -n cert-manager cert-manager-webhook-gandi-XYZ
   

5. Create a staging issuer (email addresses with the suffix example.com are forbidden).

   See letsencrypt-staging-issuer.yaml

   Don't forget to replace email invalid@example.com.

   Check status of the Issuer:

    kubectl describe issuer letsencrypt-staging
   

   You can deploy a ClusterIssuer instead : see letsencrypt-staging-clusterissuer.yaml

   Note: The production Issuer is similar.

6. Issue a Certificate for your domain: see certif-example-com.yaml

   Replace your-domain and your.domain in the certif-example-com.yaml

   Create the Certificate:

    kubectl apply -f ./examples/certificates/certif-example-com.yaml
   

   Check the status of the Certificate:

    kubectl describe certificate example-com
   

   Display the details like the common name and subject alternative names:

    kubectl get secret example-com-tls -o yaml
   

   If you deployed a ClusterIssuer : use certif-example-com-clusterissuer.yaml

7. Issue a wildcard Certificate for your domain: see certif-wildcard-example-com.yaml

   Replace your-domain and your.domain in the certif-wildcard-example-com.yaml

   Create the Certificate:

    kubectl apply -f ./examples/certificates/certif-wildcard-example-com.yaml
   

   Check the status of the Certificate:

    kubectl describe certificate wildcard-example-com
   

   Display the details like the common name and subject alternative names:

    kubectl get secret wildcard-example-com-tls -o yaml
   

   If you deployed a ClusterIssuer : use certif-wildcard-example-com-clusterissuer.yaml

8. Uninstall this webhook:

    helm uninstall cert-manager-webhook-gandi --namespace cert-manager
    kubectl delete gandi-credentials --namespace cert-manager
   

9. Uninstalling cert-manager: This is out of scope here. Refer to the official documentation.

Development

Note: If some tool (IDE or build process) fails resolving a dependency, it may be the cause that a indirect dependency uses bzr for versioning. In such a case it may help to put the bzr binary into $PATH or $GOPATH/bin.

Release process (automated with GitHub actions)

• Changes in the Go code result in the build of a Docker image and the release of a new Helm chart
• Changes at Helm chart level only, result in the release of a new Chart without building a new Docker image
• All other changes are pushed to master
• All versions are to be documented in CHANGELOG

Note: All changes to the Go code or Helm chart must go with a version tag vX.X.X to trigger the GitHub workflow

Note: Any Helm chart release results in the creation of a GitHub release

Conformance test

Please note that the test is not a typical unit or integration test. Instead it invokes the web hook in a Kubernetes-like environment which asks the web hook to really call the DNS provider (.i.e. Gandi). It attempts to create an TXT entry like cert-manager-dns01-tests.example.com, verifies the presence of the entry via Google DNS. Finally it removes the entry by calling the cleanup method of web hook.

As said above, the conformance test is run against the real Gandi API. Therefore you must have a Gandi account, a domain and an API key.

cp testdata/gandi/api-key.yaml.sample testdata/gandi/api-key.yaml
echo -n $YOUR_GANDI_API_KEY | base64 | pbcopy # or xclip
$EDITOR testdata/gandi/api-key.yaml
TEST_ZONE_NAME=example.com. make test
make clean