pkg/ipnet: Provide an IPNet structure with CIDR serialization

Use CIDR notation [1] for serliazing IPNet structures so the values
are human editable (vs. the stdlib's base64 netmasks).  It's
unfortunate that we can't update the stdlib to do this, but their
encodings are frozen [2].

[1]: https://en.wikipedia.org/wiki/Classless_Inter-Domain_Routing#CIDR_notation
[2]: https://github.com/golang/go/issues/12803#issuecomment-150673932

installer/pkg/config-generator/fixtures/kube-system.yaml

@@ -31,12 +31,8 @@ data:
       creationTimestamp: null
       name: test
     networking:
-      podCIDR:
-        IP: 10.2.0.0
-        Mask: //8AAA==
-      serviceCIDR:
-        IP: 10.3.0.0
-        Mask: //8AAA==
+      podCIDR: 10.2.0.0/16
+      serviceCIDR: 10.3.0.0/16
       type: canal
     platform:
       aws:

installer/pkg/config-generator/generator.go

@@ -19,6 +19,7 @@ import (
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 
 	"github.com/openshift/installer/installer/pkg/config"
+	"github.com/openshift/installer/pkg/ipnet"
 	"github.com/openshift/installer/pkg/types"
 )
 
@@ -185,8 +186,8 @@ func (c *ConfigGenerator) installConfig() (*types.InstallConfig, error) {
 		PullSecret: c.PullSecret,
 		Networking: types.Networking{
 			Type:        types.NetworkType(string(c.Networking.Type)),
-			ServiceCIDR: *serviceCIDR,
-			PodCIDR:     *podCIDR,
+			ServiceCIDR: ipnet.IPNet{IPNet: *serviceCIDR},
+			PodCIDR:     ipnet.IPNet{IPNet: *podCIDR},
 		},
 		Platform: platform,
 		Machines: []types.MachinePool{{

pkg/asset/installconfig/installconfig_test.go

@@ -163,12 +163,8 @@ metadata:
   creationTimestamp: null
   name: test-cluster-name
 networking:
-  podCIDR:
-    IP: ""
-    Mask: null
-  serviceCIDR:
-    IP: ""
-    Mask: null
+  podCIDR: null
+  serviceCIDR: null
   type: ""
 platform:
 %s

pkg/asset/tls/helper.go

@@ -53,7 +53,7 @@ func genDNSNamesForAPIServerCertKey(cfg *types.InstallConfig) ([]string, error)
 }
 
 func genIPAddressesForAPIServerCertKey(cfg *types.InstallConfig) ([]net.IP, error) {
-	apiServerAddress, err := cidrhost(cfg.Networking.ServiceCIDR, 1)
+	apiServerAddress, err := cidrhost(cfg.Networking.ServiceCIDR.IPNet, 1)
 	if err != nil {
 		return nil, err
 	}
@@ -72,7 +72,7 @@ func genDNSNamesForOpenshiftAPIServerCertKey(cfg *types.InstallConfig) ([]string
 }
 
 func genIPAddressesForOpenshiftAPIServerCertKey(cfg *types.InstallConfig) ([]net.IP, error) {
-	apiServerAddress, err := cidrhost(cfg.Networking.ServiceCIDR, 1)
+	apiServerAddress, err := cidrhost(cfg.Networking.ServiceCIDR.IPNet, 1)
 	if err != nil {
 		return nil, err
 	}

pkg/ipnet/ipnet.go

@@ -0,0 +1,49 @@
+// Package ipnet wraps net.IPNet to get CIDR serialization.
+package ipnet
+
+import (
+	"encoding/json"
+	"net"
+	"reflect"
+)
+
+var nullString = "null"
+var nullBytes = []byte(nullString)
+var emptyIPNet = net.IPNet{}
+
+// IPNet wraps net.IPNet to get CIDR serialization.
+type IPNet struct {
+	net.IPNet
+}
+
+// MarshalJSON interface for an IPNet
+func (ipnet IPNet) MarshalJSON() (data []byte, err error) {
+	if reflect.DeepEqual(ipnet.IPNet, emptyIPNet) {
+		return nullBytes, nil
+	}
+
+	return json.Marshal(ipnet.String())
+}
+
+// UnmarshalJSON interface for an IPNet
+func (ipnet *IPNet) UnmarshalJSON(b []byte) (err error) {
+	if string(b) == nullString {
+		ipnet.IP = net.IP{}
+		ipnet.Mask = net.IPMask{}
+		return nil
+	}
+
+	var cidr string
+	err = json.Unmarshal(b, &cidr)
+	if err != nil {
+		return err
+	}
+
+	ip, net, err := net.ParseCIDR(cidr)
+	if err != nil {
+		return err
+	}
+	ipnet.IP = ip
+	ipnet.Mask = net.Mask
+	return nil
+}

pkg/ipnet/ipnet_test.go

@@ -0,0 +1,62 @@
+package ipnet
+
+import (
+	"encoding/json"
+	"net"
+	"testing"
+)
+
+func assertJSON(t *testing.T, data interface{}, expected string) {
+	actualBytes, err := json.Marshal(data)
+	if err != nil {
+		t.Fatal(err)
+	}
+	actual := string(actualBytes)
+
+	if actual != expected {
+		t.Fatalf("%s != %s", actual, expected)
+	}
+}
+
+func TestMarshal(t *testing.T) {
+	stdlibIPNet := &net.IPNet{
+		IP:   net.IP{192, 168, 0, 10},
+		Mask: net.IPv4Mask(255, 255, 255, 0),
+	}
+	assertJSON(t, stdlibIPNet, "{\"IP\":\"192.168.0.10\",\"Mask\":\"////AA==\"}")
+	wrappedIPNet := &IPNet{IPNet: *stdlibIPNet}
+	assertJSON(t, wrappedIPNet, "\"192.168.0.10/24\"")
+	assertJSON(t, &IPNet{}, "null")
+	assertJSON(t, nil, "null")
+}
+
+func TestUnmarshal(t *testing.T) {
+	for _, ipNetIn := range []*IPNet{
+		nil,
+		{IPNet: net.IPNet{
+			IP:   net.IP{192, 168, 0, 10},
+			Mask: net.IPv4Mask(255, 255, 255, 0),
+		}},
+	} {
+		data, err := json.Marshal(ipNetIn)
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		t.Run(string(data), func(t *testing.T) {
+			var ipNetOut *IPNet
+			err := json.Unmarshal(data, &ipNetOut)
+			if err != nil {
+				t.Fatal(err)
+			}
+
+			if ipNetIn == nil {
+				if ipNetOut != nil {
+					t.Fatalf("%v != %v", ipNetOut, ipNetIn)
+				}
+			} else if ipNetOut.String() != ipNetIn.String() {
+				t.Fatalf("%v != %v", ipNetOut, ipNetIn)
+			}
+		})
+	}
+}

pkg/types/installconfig.go

@@ -3,6 +3,7 @@ package types
 import (
 	"net"
 
+	"github.com/openshift/installer/pkg/ipnet"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 )
 
@@ -58,8 +59,8 @@ type Platform struct {
 // Networking defines the pod network provider in the cluster.
 type Networking struct {
 	Type        NetworkType `json:"type"`
-	ServiceCIDR net.IPNet   `json:"serviceCIDR"`
-	PodCIDR     net.IPNet   `json:"podCIDR"`
+	ServiceCIDR ipnet.IPNet `json:"serviceCIDR"`
+	PodCIDR     ipnet.IPNet `json:"podCIDR"`
 }
 
 // NetworkType defines the pod network provider in the cluster.