Adding initial version of Kubernetes backend (#552)

Co-authored-by: laszlocph <laszlo@laszlo.cloud>
Co-authored-by: 6543 <6543@obermui.de>
Co-authored-by: Rynoxx <rynoxx@grid-servers.net>

pipeline/backend/kubernetes/volume_test.go

@@ -0,0 +1,62 @@
+package kubernetes
+
+import (
+	"encoding/json"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestPersistentVolumeClaim(t *testing.T) {
+	expectedRwx := `
+	{
+	  "metadata": {
+	    "name": "someName",
+	    "namespace": "someNamespace",
+	    "creationTimestamp": null
+	  },
+	  "spec": {
+	    "accessModes": [
+	      "ReadWriteMany"
+	    ],
+	    "resources": {
+	      "requests": {
+	        "storage": "1Gi"
+	      }
+	    },
+	    "storageClassName": "local-storage"
+	  },
+	  "status": {}
+	}`
+
+	expectedRwo := `
+	{
+	  "metadata": {
+	    "name": "someName",
+	    "namespace": "someNamespace",
+	    "creationTimestamp": null
+	  },
+	  "spec": {
+	    "accessModes": [
+	      "ReadWriteOnce"
+	    ],
+	    "resources": {
+	      "requests": {
+	        "storage": "1Gi"
+	      }
+	    },
+	    "storageClassName": "local-storage"
+	  },
+	  "status": {}
+	}`
+
+	pvc := PersistentVolumeClaim("someNamespace", "someName", "local-storage", "1Gi", true)
+	j, err := json.Marshal(pvc)
+	assert.Nil(t, err)
+	assert.JSONEq(t, expectedRwx, string(j))
+
+	pvc = PersistentVolumeClaim("someNamespace", "someName", "local-storage", "1Gi", false)
+	j, err = json.Marshal(pvc)
+	assert.Nil(t, err)
+	assert.JSONEq(t, expectedRwo, string(j))
+}