Draft of tutorial for Google's Public CA

content/docs/tutorials/README.md

@@ -29,6 +29,7 @@ for you to learn from. Take a look!
 - [Syncing Secrets Across Namespaces](./syncing-secrets-across-namespaces.md):
   Learn how to synchronize Kubernetes Secret resources across namespaces using extensions such as: reflector, kubed and kubernetes-replicator.
 - [Obtaining SSL certificates with the ZeroSSL](./zerossl/zerossl.md): Tutorial describing usage of the ZeroSSL as external ACME server.
+- [Configuring Google's Public Certificate Authority](./google-public-ca/README.md): Configure Google's new Public CA
 
 ### External Tutorials
 

content/docs/tutorials/google-public-ca/README.md

@@ -0,0 +1,105 @@
+---
+title: "Configuring Google's Public Certificate Authority"
+linktitle: "Configuring Google's Public Certificate Authority"
+---
+
+For years we used `cert-manager` to provision TLS certificates from ZeroSSL. Their ACME service is free, but we've really gotten what we paid for. Service outages were common, and more recently ZeroSSL added undocumented rate limiting for HTTP requests to their ACME API. This change put us in the same situation as this `cert-manager` user: <https://github.com/cert-manager/cert-manager/issues/5867>. We began looking for alternative certificate authorities that support the ACME protocol.
+
+About a year ago, Google announced ACME protocol support for their new Public Certificate Authority. This is the alternative we're looking for. We've configured our system to use this and below I'll show how you can too. We'll follow part of Google's tutorial, but instead of using `certbot`, we'll configure a `ClusterIssuer` and associated `Secret` for `cert-manager`. <https://cloud.google.com/certificate-manager/docs/public-ca-tutorial>
+
+### Prerequisites
+
+- A Google Cloud Platform Account and [Project](https://cloud.google.com/resource-manager/docs/creating-managing-projects)
+- [`gcloud` CLI installed](https://cloud.google.com/sdk/docs/install) and [initialized](https://cloud.google.com/sdk/docs/initializing)
+- `cert-manager` installed on a Kubernetes Cluster with public `Ingress` support
+
+Begin by generating External Account Binding credentials within your GCP Project.
+
+```sh
+$ gcloud config set project uffizzi-production-gke
+Updated property [core/project]
+
+$ gcloud beta publicca external-account-keys create
+```
+
+This will output a private key and an ID number. Take the resulting `b64MacKey` value and base64 encode it.
+
+```sh
+echo -n [the b64MacKey] | base64 --wrap=0
+```
+
+Copy that value into a YAML file specifying two Kubernetes Resources, a `ClusterIssuer` and a `Secret`.
+
+```yaml
+apiVersion: cert-manager.io/v1
+kind: ClusterIssuer
+metadata:
+  name: google-public-ca
+spec:
+  acme:
+    email: info@example.com
+    externalAccountBinding:
+      keyID: 03ffa4c7d6bf48853fb5e63b106e83f1
+      keySecretRef:
+        key: eab_hmac_key
+        name: google-public-ca-eab-secret
+    privateKeySecretRef:
+      name: google-public-ca-tls
+    server: https://dv.acme-v02.api.pki.goog/directory
+    solvers:
+    - http01:
+        ingress:
+          class: nginx
+---
+apiVersion: v1
+kind: Secret
+metadata:
+  name: google-public-ca-eab-secret
+  namespace: cert-manager
+type: Opaque
+data:
+  eab_hmac_key: [the base64-encoded key]
+```
+
+Apply the YAML file you just wrote to create the Kubernetes resources.
+
+```sh
+kubectl apply -f google-public-ca.yaml
+```
+
+Confirm that `cert-manager` successfully registered the credentials with Google's ACME service.
+
+```sh
+kubectl get clusterissuer google-public-ca -o json | jq '.status.conditions'
+```
+
+```json
+[
+  {
+    "lastTransitionTime": "2023-04-06T20:33:55Z",
+    "message": "The ACME account was registered with the ACME server",
+    "observedGeneration": 1,
+    "reason": "ACMEAccountRegistered",
+    "status": "True",
+    "type": "Ready"
+  }
+]
+```
+
+Now specify an `Ingress` with this annotation and `cert-manager` will provision a certificate from Google's Public CA.
+
+```yaml
+apiVersion: networking.k8s.io/v1
+kind: Ingress
+metadata:
+  annotations:
+    cert-manager.io/cluster-issuer: google-public-ca
+```
+
+(In our case, we manage these k8s resources using terraform, specifically the `kubernetes_secret` and `kubernetes_manifest` resources.)
+
+Google's Public Certificate Authority is completely free to use, so long as you have a GCP Project to meter its quotas. Unlike ZeroSSL, Google's quotas are published here: <https://cloud.google.com/certificate-manager/docs/quotas#public_ca_request_quotas>
+
+We have not yet bumped up against these quota limits, and now our customers are consistently provisioning certificates with many additional hostnames. This is another example of infrastructure work we do so you can deploy ephemeral environments for all of your project's branches. If you have questions about this or any of our infrastructure, join us on Slack!
+
+(This tutorial was originally authored by Adam Vollrath and [published on Uffizzi's blog](https://www.uffizzi.com/blog/ditching-zerossl-for-google-public-certificate-authority-for-ssl-certificates-via-cert-manager-and-acme-protocol).)