feat: Support configuring minimum k8s version that Knative will accept

Fixes gh-50

Author: ThomasVitale

README.md

@@ -104,6 +104,7 @@ The Knative Serving package has the following configurable properties.
 | `policies.include` | `false` | Whether to include the out-of-the-box Kyverno policies to validate and secure the package installation. |
 | `domain_name` | `""` | Domain name for Knative Services. It must be a valid DNS name. |
 | `ingress_issuer` | `""` | A reference to the ClusterIssuer to use if you want to enable autoTLS. |
+| `min_kubernetes_version` | `""` | The minimum Kubernetes version that this package will accept as valid. If not set, Knative Serving will accept the last 3 minor versions of Kubernetes. |
 
 Settings for the Knative Serving workloads.
 

package/config/overlays/kubernetes-version.yml

@@ -0,0 +1,15 @@
+#@ load("@ytt:data", "data")
+#@ load("@ytt:overlay", "overlay")
+
+#@overlay/match by=overlay.subset({"kind":"Deployment"}), expects="6+"
+---
+spec:
+  template:
+    spec:
+      #@overlay/match missing_ok=True
+      containers:
+        #@overlay/match by=overlay.all
+        - env:
+          #@ if/end data.values.min_kubernetes_version != "":
+          - name: KUBERNETES_MIN_VERSION
+            value: #@ data.values.min_kubernetes_version

package/config/values-schema.yml

@@ -17,6 +17,9 @@ domain_name: ""
 #@schema/examples ("Kadras private CA", "kadras-ca-issuer")
 ingress_issuer: ""
 
+#@schema/desc "The minimum Kubernetes version that this package will accept as valid. If not set, Knative Serving will accept the last 3 minor versions of Kubernetes."
+min_kubernetes_version: ""
+
 #@schema/desc "Settings for the Knative Serving workloads."
 workloads:
   activator:

test/integration/default/config/values.yml

@@ -8,3 +8,4 @@ stringData:
   values.yaml: |
     domain_name: "127.0.0.1.sslip.io"
     ingress_issuer: "kadras-ca-issuer"
+    min_kubernetes_version: "1.30.0"