NETOBSERV-924 adapt to new ovn annotation format

The format of this annotation has changed between ocp 4.12 and 4.13
This kind of IPs are typically used in host-network traffic

pkg/pipeline/transform/kubernetes/cni/ovn_kubernetes.go

@@ -43,27 +43,49 @@ func AddOvnIPs(ips []string, node *v1.Node) []string {
 	return ips
 }
 
+func unmarshalAnnotation(annot []byte) (string, error) {
+	// Depending on OVN (OCP) version, the annotation might be JSON-encoded as a string, or an array of strings
+	// Try first as string (legacy)
+	var subnetsAsString map[string]string
+	err := json.Unmarshal(annot, &subnetsAsString)
+	if err == nil {
+		if subnet, ok := subnetsAsString["default"]; ok {
+			return subnet, nil
+		}
+		return "", fmt.Errorf("unexpected content for annotation %s: %s", ovnSubnetAnnotation, annot)
+	}
+
+	var subnetsAsArray map[string][]string
+	err = json.Unmarshal(annot, &subnetsAsArray)
+	if err == nil {
+		if subnets, ok := subnetsAsArray["default"]; ok {
+			if len(subnets) > 0 {
+				return subnets[0], nil
+			}
+		}
+		return "", fmt.Errorf("unexpected content for annotation %s: %s", ovnSubnetAnnotation, annot)
+	}
+
+	return "", fmt.Errorf("cannot read annotation %s: %v", ovnSubnetAnnotation, err)
+}
+
 func findOvnMp0IP(annotations map[string]string) (string, error) {
 	if subnetsJSON, ok := annotations[ovnSubnetAnnotation]; ok {
-		var subnets map[string]string
-		err := json.Unmarshal([]byte(subnetsJSON), &subnets)
+		subnet, err := unmarshalAnnotation([]byte(subnetsJSON))
 		if err != nil {
-			return "", fmt.Errorf("cannot read annotation %s: %v", ovnSubnetAnnotation, err)
+			return "", err
 		}
-		if subnet, ok := subnets["default"]; ok {
-			// From subnet like 10.128.0.0/23, we want to index IP 10.128.0.2
-			ip0, _, err := net.ParseCIDR(subnet)
-			if err != nil {
-				return "", err
-			}
-			ip4 := ip0.To4()
-			if ip4 == nil {
-				// TODO: what's the rule with ipv6?
-				return "", nil
-			}
-			return fmt.Sprintf("%d.%d.%d.2", ip4[0], ip4[1], ip4[2]), nil
+		// From subnet like 10.128.0.0/23, we want to index IP 10.128.0.2
+		ip0, _, err := net.ParseCIDR(subnet)
+		if err != nil {
+			return "", err
+		}
+		ip4 := ip0.To4()
+		if ip4 == nil {
+			// TODO: what's the rule with ipv6?
+			return "", nil
 		}
-		return "", fmt.Errorf("unexpected content for annotation %s: %s", ovnSubnetAnnotation, subnetsJSON)
+		return fmt.Sprintf("%d.%d.%d.2", ip4[0], ip4[1], ip4[2]), nil
 	}
 	// Annotation not present (expected if not using ovn-kubernetes) => just ignore, no error
 	return "", nil

pkg/pipeline/transform/kubernetes/cni/ovn_kubernetes_test.go

@@ -45,10 +45,17 @@ func TestFindOvnMp0IP(t *testing.T) {
 	require.Contains(t, err.Error(), "invalid CIDR address")
 	require.Empty(t, ip)
 
-	// Valid annotation => no error, ip
+	// Valid annotation (legacy) => no error, ip
 	ip, err = findOvnMp0IP(map[string]string{
 		ovnSubnetAnnotation: `{"default":"10.129.0.0/23"}`,
 	})
 	require.NoError(t, err)
 	require.Equal(t, "10.129.0.2", ip)
+
+	// Valid annotation => no error, ip
+	ip, err = findOvnMp0IP(map[string]string{
+		ovnSubnetAnnotation: `{"default":["10.129.0.0/23"]}`,
+	})
+	require.NoError(t, err)
+	require.Equal(t, "10.129.0.2", ip)
 }