feat(helm-namespace): add example for Helm namespace inheritance and related resources

Author: Skaronator

examples/README.md

@@ -42,6 +42,8 @@ Advanced Usage
    * [last mile helm](chart.md) - Make last mile modifications to
      a helm chart.
 
+   * [helm namespace inheritance](helmNamespace/README.md) - Verify that an overlay namespace fills unset namespaces in Helm output without overwriting explicit chart namespaces.
+
    * [secret generation](secretGeneratorPlugin.md) - Generating secrets from a plugin.
 
    * [remote sources](goGetterGeneratorPlugin.md) - Generating from remote sources.

examples/helmNamespace/README.md

@@ -0,0 +1,53 @@
+# Helm Namespace Example
+
+This example exercises namespace transformation on resources generated from a local Helm chart.
+
+The example kustomization sets a namespace for Helm-generated resources that do not already declare one, while preserving any namespace explicitly emitted by the chart.
+
+## Build the example
+
+This example defines the `helm` command as:
+
+<!-- @defineHelmCommand @testHelm -->
+```sh
+helmCommand=${MYGOBIN:-~/go/bin}/helmV3
+```
+
+Use the checked-in example:
+
+<!-- @defineExampleHome @testHelm -->
+```sh
+EXAMPLE_HOME=examples/helmNamespace
+```
+
+Build the example with Helm enabled:
+
+<!-- @buildOverlay @testHelm -->
+```sh
+output=$(kustomize build \
+  --enable-helm \
+  --helm-command "$helmCommand" \
+  "$EXAMPLE_HOME")
+printf '%s\n' "$output"
+```
+
+The Service is emitted by the chart without a namespace, so the example namespace should be applied:
+
+<!-- @checkMissingNamespaceFilled @testHelm -->
+```sh
+printf '%s\n' "$output" | grep -A4 'name: chart-service' | grep 'namespace: top-level-ns'
+```
+
+The ConfigMap is emitted by the chart with an explicit namespace, so that value should be preserved:
+
+<!-- @checkExistingNamespacePreserved @testHelm -->
+```sh
+printf '%s\n' "$output" | grep -A4 'name: chart-config' | grep 'namespace: chart-owned-ns'
+```
+
+The Secret is emitted by the chart with an release namespace, so that value should be preserved:
+
+<!-- @checkExistingNamespacePreserved @testHelm -->
+```sh
+printf '%s\n' "$output" | grep -A4 'name: chart-secret' | grep 'namespace: chart-ns'
+```

examples/helmNamespace/charts/namespace-fill/Chart.yaml

@@ -0,0 +1,4 @@
+apiVersion: v2
+name: namespace-fill
+version: 0.1.0
+type: application

examples/helmNamespace/charts/namespace-fill/templates/configmap.yaml

@@ -0,0 +1,7 @@
+apiVersion: v1
+kind: ConfigMap
+metadata:
+  name: chart-config
+  namespace: chart-owned-ns
+data:
+  owner: helm-chart

examples/helmNamespace/charts/namespace-fill/templates/secrets.yaml

@@ -0,0 +1,7 @@
+apiVersion: v1
+kind: Secret
+metadata:
+  name: chart-secret
+  namespace: {{ .Release.Namespace }}
+data:
+  .secret-file: dmFsdWUtMg0KDQo=

examples/helmNamespace/charts/namespace-fill/templates/service.yaml

@@ -0,0 +1,10 @@
+apiVersion: v1
+kind: Service
+metadata:
+  name: chart-service
+spec:
+  selector:
+    app: chart-service
+  ports:
+  - port: 80
+    targetPort: 8080

examples/helmNamespace/charts/namespace-fill/values.yaml

@@ -0,0 +1,11 @@
+apiVersion: kustomize.config.k8s.io/v1beta1
+kind: Kustomization
+
+namespace: top-level-ns
+
+helmGlobals:
+  chartHome: charts
+
+helmCharts:
+- name: namespace-fill
+  namespace: chart-ns

examples/helmNamespace/kustomization.yaml

@@ -39,6 +39,7 @@ if onLinuxAndNotOnRemoteCI; then
     echo "On linux, and not on remote CI.  Running helm tests."
     make $MYGOBIN/helmV3
     mdrip --mode test --label testHelm examples/chart.md
+    mdrip --mode test --label testHelm examples/helmNamespace/README.md
   else
     echo "Skipping helm tests against $version."
     echo "Helm chart inflator has new features (includeCRD) only in HEAD."