Detecting Knative installation
Easiest way to see if Knative components are installed is to list the Namespaces in a cluster:
$ kubectl get namespaces NAME STATUS AGE default Active 134d istio-system Active 134d knative-serving Active 134d knative-eventing Active 134d kube-public Active 134d kube-system Active 134d
Only one Knative installation can exist in a cluster. This is because Knative controllers look at Kubernetes custom resource definitions (CRDs) they install to the cluster (like Service, Revision, Configuration) and they would be racing each other.