Drop GO111MODULE, drop v1beta1 admission review, improve flag desc, h…

…oist and comment webhook name as constant

Signed-off-by: Matt Moore <mattomata@gmail.com>

.github/workflows/kind-e2e-cosigned.yaml

@@ -41,7 +41,6 @@ jobs:
 
     env:
       GOPATH: ${{ github.workspace }}
-      GO111MODULE: on
       # https://github.com/google/go-containerregistry/pull/125 allows insecure registry for
       # '*.local' hostnames.
       REGISTRY_NAME: registry.local

cmd/cosign/webhook/main.go

@@ -36,7 +36,12 @@ import (
 	cwebhook "github.com/sigstore/cosign/pkg/cosign/kubernetes/webhook"
 )
 
-var secretName = flag.String("secret-name", "", "The name of the secret in the webhook's namespace.")
+var secretName = flag.String("secret-name", "", "The name of the secret in the webhook's namespace that holds the public key for verification.")
+
+// webhookName holds the name of the validating webhook to set up with the
+// types we are watching.  If this changes, you must also change:
+//    ./config/500-webhook-configuration.yaml
+const webhookName = "cosigned.sigstore.dev"
 
 func main() {
 	opts := webhook.Options{
@@ -61,7 +66,7 @@ func NewValidatingAdmissionController(ctx context.Context, cmw configmap.Watcher
 
 	return validation.NewAdmissionController(ctx,
 		// Name of the resource webhook.
-		"cosigned.sigstore.dev",
+		webhookName,
 
 		// The path on which to serve the webhook.
 		"/validations",

config/500-webhook-configuration.yaml

@@ -24,7 +24,7 @@ webhooks:
     - key: cosigned.sigstore.dev/include
       operator: In
       values: ["true"]
-  admissionReviewVersions: [v1beta1, v1]
+  admissionReviewVersions: [v1]
   clientConfig:
     service:
       name: webhook