Add CI for images/kube-webhook-certgen (#7717)

As a follow up to PR #7641, this commit adds some basic e2e tests for
kube-webhook-certgen image.

Signed-off-by: Mateusz Gozdek <mgozdek@microsoft.com>

.github/workflows/ci.yaml

@@ -276,4 +276,40 @@ jobs:
       - name: kube-webhook-certgen image build
         if: ${{ steps.filter-images.outputs.kube-webhook-certgen == 'true' }}
         run: |
-          cd images/kube-webhook-certgen && make build
+          cd images/kube-webhook-certgen && make build
+
+  test-image:
+    runs-on: ubuntu-latest
+    env:
+      PLATFORMS: linux/amd64
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v2
+
+      - uses: dorny/paths-filter@v2
+        id: filter-images
+        with:
+          token: ${{ secrets.GITHUB_TOKEN }}
+          filters: |
+            kube-webhook-certgen:
+              - 'images/kube-webhook-certgen/**'
+
+      - name: Create Kubernetes cluster
+        id: kind
+        if: ${{ steps.filter-images.outputs.kube-webhook-certgen == 'true' }}
+        uses: engineerd/setup-kind@v0.5.0
+        with:
+          version: v0.11.1
+          image: kindest/node:v1.21.1
+
+      - name: Set up Go 1.17
+        id: go
+        if: ${{ steps.filter-images.outputs.kube-webhook-certgen == 'true' }}
+        uses: actions/setup-go@v2
+        with:
+          go-version: 1.17
+
+      - name: kube-webhook-certgen image build
+        if: ${{ steps.filter-images.outputs.kube-webhook-certgen == 'true' }}
+        run: |
+          cd images/kube-webhook-certgen && make test test-e2e