'overlay' conflist generator for CNS (#2010)

Author: pjohnst5

cns/cniconflist/generator.go

@@ -53,6 +53,11 @@ type DualStackOverlayGenerator struct {
 	Writer io.WriteCloser
 }
 
+// OverlayGenerator generates the Azure CNI conflist for all Overlay scenarios
+type OverlayGenerator struct {
+	Writer io.WriteCloser
+}
+
 // CiliumGenerator generates the Azure CNI conflist for the Cilium scenario
 type CiliumGenerator struct {
 	Writer io.WriteCloser
@@ -74,6 +79,14 @@ func (v *DualStackOverlayGenerator) Close() error {
 	return nil
 }
 
+func (v *OverlayGenerator) Close() error {
+	if err := v.Writer.Close(); err != nil {
+		return errors.Wrap(err, "error closing generator")
+	}
+
+	return nil
+}
+
 func (v *CiliumGenerator) Close() error {
 	if err := v.Writer.Close(); err != nil {
 		return errors.Wrap(err, "error closing generator")

cns/cniconflist/generator_linux.go

@@ -80,6 +80,34 @@ func (v *DualStackOverlayGenerator) Generate() error {
 	return nil
 }
 
+// Generate writes the CNI conflist to the Generator's output stream
+func (v *OverlayGenerator) Generate() error {
+	conflist := cniConflist{
+		CNIVersion: overlaycniVersion,
+		Name:       overlaycniName,
+		Plugins: []any{
+			cni.NetworkConfig{
+				Type:              overlaycniType,
+				Mode:              cninet.OpModeTransparent,
+				IPsToRouteViaHost: []string{nodeLocalDNSIP},
+				IPAM: cni.IPAM{
+					Type: network.AzureCNS,
+					Mode: string(util.Overlay),
+				},
+			},
+			portmapConfig,
+		},
+	}
+
+	enc := json.NewEncoder(v.Writer)
+	enc.SetIndent("", "\t")
+	if err := enc.Encode(conflist); err != nil {
+		return errors.Wrap(err, "error encoding conflist to json")
+	}
+
+	return nil
+}
+
 // Generate writes the CNI conflist to the Generator's output stream
 func (v *CiliumGenerator) Generate() error {
 	conflist := cniConflist{

cns/cniconflist/generator_linux_test.go

@@ -18,7 +18,7 @@ func (b *bufferWriteCloser) Close() error {
 }
 
 func TestGenerateV4OverlayConflist(t *testing.T) {
-	fixture := "testdata/fixtures/azure-linux-swift-overlay.conflist"
+	fixture := "testdata/fixtures/azure-linux-swift-v4overlay.conflist"
 
 	buffer := new(bytes.Buffer)
 	g := cniconflist.V4OverlayGenerator{Writer: &bufferWriteCloser{buffer}}
@@ -47,6 +47,21 @@ func TestGenerateDualStackOverlayConflist(t *testing.T) {
 	assert.Equal(t, removeNewLines(fixtureBytes), removeNewLines(buffer.Bytes()))
 }
 
+func TestGenerateOverlayConflist(t *testing.T) {
+	fixture := "testdata/fixtures/azure-linux-swift-overlay.conflist"
+
+	buffer := new(bytes.Buffer)
+	g := cniconflist.OverlayGenerator{Writer: &bufferWriteCloser{buffer}}
+	err := g.Generate()
+	assert.NoError(t, err)
+
+	fixtureBytes, err := os.ReadFile(fixture)
+	assert.NoError(t, err)
+
+	// remove newlines and carriage returns in case these UTs are running on Windows
+	assert.Equal(t, removeNewLines(fixtureBytes), removeNewLines(buffer.Bytes()))
+}
+
 func TestGenerateCiliumConflist(t *testing.T) {
 	fixture := "testdata/fixtures/cilium.conflist"
 

cns/cniconflist/generator_windows.go

@@ -14,6 +14,10 @@ func (v *DualStackOverlayGenerator) Generate() error {
 	return errNotImplemented
 }
 
+func (v *OverlayGenerator) Generate() error {
+	return errNotImplemented
+}
+
 func (v *CiliumGenerator) Generate() error {
 	return errNotImplemented
 }

cns/cniconflist/testdata/fixtures/azure-linux-swift-overlay.conflist

@@ -8,9 +8,8 @@
 			"ipsToRouteViaHost": [
 				"169.254.20.10"
 			],
-			"executionMode": "v4swift",
 			"ipam": {
-				"mode": "v4overlay",
+				"mode": "overlay",
 				"type": "azure-cns"
 			},
 			"dns": {},

cns/cniconflist/testdata/fixtures/azure-linux-swift-v4overlay.conflist

@@ -0,0 +1,30 @@
+{
+	"cniVersion": "0.3.0",
+	"name": "azure",
+	"plugins": [
+		{
+			"type": "azure-vnet",
+			"mode": "transparent",
+			"ipsToRouteViaHost": [
+				"169.254.20.10"
+			],
+			"executionMode": "v4swift",
+			"ipam": {
+				"mode": "v4overlay",
+				"type": "azure-cns"
+			},
+			"dns": {},
+			"runtimeConfig": {
+				"dns": {}
+			},
+			"windowsSettings": {}
+		},
+		{
+			"type": "portmap",
+			"capabilities": {
+				"portMappings": true
+			},
+			"snat": true
+		}
+	]
+}

cns/service/main.go

@@ -88,6 +88,7 @@ type cniConflistScenario string
 const (
 	scenarioV4Overlay        cniConflistScenario = "v4overlay"
 	scenarioDualStackOverlay cniConflistScenario = "dualStackOverlay"
+	scenarioOverlay          cniConflistScenario = "overlay"
 	scenarioCilium           cniConflistScenario = "cilium"
 )
 
@@ -539,6 +540,8 @@ func main() {
 			conflistGenerator = &cniconflist.V4OverlayGenerator{Writer: writer}
 		case scenarioDualStackOverlay:
 			conflistGenerator = &cniconflist.DualStackOverlayGenerator{Writer: writer}
+		case scenarioOverlay:
+			conflistGenerator = &cniconflist.OverlayGenerator{Writer: writer}
 		case scenarioCilium:
 			conflistGenerator = &cniconflist.CiliumGenerator{Writer: writer}
 		default: