This release supports the (not yet released) v1 Google Certificate Authority Service API.
Docker images are available at quay.io/jetstack/cert-manager-google-cas-issuer:0.5.0-beta.0
One-line install: kubectl apply -f https://github.com/jetstack/google-cas-issuer/releases/download/v0.5.0-beta.0/google-cas-issuer-v0.5.0-beta.0.yaml