[nad] Add GetJSONPathFromConfig

Adds function to return the result of the jsonPath as string from
the NetworkAttachmentDefinition config. If the NAD has no config,
an empty string is returned.
The jsonPath must be in the format e.g. ".ipam"

Signed-off-by: Martin Schuppert <[email protected]>

modules/common/networkattachment/networkattachment.go

@@ -204,3 +204,37 @@ func EnsureNetworksAnnotation(
 
 	return annotationString, nil
 }
+
+// GetJSONPathFromConfig - returns the result of the jsonPath as string
+// from the NetworkAttachmentDefinition config.
+// if the NAD has no config, an empty string is returned.
+// The jsonPath must be in the format e.g. ".ipam"
+func GetJSONPathFromConfig(netAtt networkv1.NetworkAttachmentDefinition, path string) (string, error) {
+	var data interface{}
+	buf := new(bytes.Buffer)
+
+	if netAtt.Spec.Config == "" {
+		return buf.String(), nil
+	}
+
+	if err := json.Unmarshal([]byte(netAtt.Spec.Config), &data); err != nil {
+		return "", fmt.Errorf("failed to unmarshal JSON data: %w", err)
+	}
+
+	// use jsonpath to parse the cni config
+	jp := jsonpath.New(netAtt.Name)
+
+	// Parse the JSONPath template to get the ipam
+	err := jp.Parse(fmt.Sprintf(`{.%s}`, path))
+	if err != nil {
+		return "", fmt.Errorf("parse template error: %w", err)
+	}
+
+	// get the ipam from the config
+	err = jp.Execute(buf, data)
+	if err != nil {
+		return "", fmt.Errorf("parse execute template against nad %+v error: %w", netAtt.Spec.Config, err)
+	}
+
+	return buf.String(), nil
+}

modules/common/networkattachment/networkattachment_test.go

@@ -291,3 +291,79 @@ func TestEnsureNetworksAnnotation(t *testing.T) {
 		})
 	}
 }
+
+func TestGetJSONPathFromConfig(t *testing.T) {
+
+	tests := []struct {
+		name string
+		nad  networkv1.NetworkAttachmentDefinition
+		path string
+		want string
+	}{
+		{
+			name: "No config",
+			nad:  networkv1.NetworkAttachmentDefinition{},
+			path: ".ipam",
+			want: "",
+		},
+		{
+			name: "get .name",
+			nad: networkv1.NetworkAttachmentDefinition{
+				ObjectMeta: metav1.ObjectMeta{Name: "one", Namespace: "foo"},
+				Spec: networkv1.NetworkAttachmentDefinitionSpec{
+					Config: `
+			{
+			  "cniVersion": "0.3.1",
+			  "name": "internalapi",
+			  "type": "macvlan",
+			  "master": "internalapi",
+			  "ipam": {
+			    "type": "whereabouts",
+			    "range": "172.17.0.0/24",
+			    "range_start": "172.17.0.30",
+			    "range_end": "172.17.0.70"
+			  }
+			}
+			`,
+				},
+			},
+			path: ".name",
+			want: "internalapi",
+		},
+		{
+			name: "get .ipam.range",
+			nad: networkv1.NetworkAttachmentDefinition{
+				ObjectMeta: metav1.ObjectMeta{Name: "one", Namespace: "foo"},
+				Spec: networkv1.NetworkAttachmentDefinitionSpec{
+					Config: `
+			{
+			  "cniVersion": "0.3.1",
+			  "name": "internalapi",
+			  "type": "macvlan",
+			  "master": "internalapi",
+			  "ipam": {
+			    "type": "whereabouts",
+			    "range": "172.17.0.0/24",
+			    "range_start": "172.17.0.30",
+			    "range_end": "172.17.0.70"
+			  }
+			}
+			`,
+				},
+			},
+			path: ".ipam.range",
+			want: "172.17.0.0/24",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			g := NewWithT(t)
+
+			networkAnnotation, err := GetJSONPathFromConfig(tt.nad, tt.path)
+			g.Expect(err).NotTo(HaveOccurred())
+			g.Expect(networkAnnotation).To(HaveLen(len(tt.want)))
+			g.Expect(networkAnnotation).To(BeEquivalentTo(tt.want))
+		})
+	}
+}