Consul Helm chart: Connect Injector service not working
I was reading the documentation to learn more about the admission controllers, when I read the prerequisites; the pertinent one being 


  Ensure that MutatingAdmissionWebhook and ValidatingAdmissionWebhook
  admission controllers are enabled


Per the docs there is a recommended set of controllers to use:


  --enable-admission-plugins=NamespaceLifecycle,LimitRanger,ServiceAccount,DefaultStorageClass,DefaultTolerationSeconds,MutatingAdmissionWebhook,ValidatingAdmissionWebhook,Priority,ResourceQuota


I manage K8s clusters with Rancher in non-test environments. By default, Rancher only enables a few of these controllers:


  NamespaceLifecycle,LimitRanger,ServiceAccount,PersistentVolumeLabel,DefaultStorageClass,DefaultTolerationSeconds,ResourceQuota


When I upgraded the cluster, this did not get enabled as I suspected with just the version upgrade. After updating the Rancher K8s configuration and applying the changes, I successfully spun up the test client/server deployments which successfully injected the envoy containers and registered the services in Consul.

TL;DR: RTFM