feat: CNS writes SWIFT conflist (#2110)

* cns writes swift conflist

* gofumpt
ed

* var naming

* add swift scenario to switch

cns/cniconflist/generator.go

@@ -16,6 +16,9 @@ const (
 	overlaycniName    = "azure"                   //nolint:unused,deadcode,varcheck // used in linux
 	overlaycniType    = "azure-vnet"              //nolint:unused,deadcode,varcheck // used in linux
 	nodeLocalDNSIP    = "169.254.20.10"           //nolint:unused,deadcode,varcheck // used in linux
+	azurecniVersion   = "0.3.0"                   //nolint:unused,deadcode,varcheck // used in linux
+	azureName         = "azure"                   //nolint:unused,deadcode,varcheck // used in linux
+	azureType         = "azure-vnet"              //nolint:unused,deadcode,varcheck // used in linux
 )
 
 // cniConflist represents the containernetworking/cni/pkg/types.NetConfList
@@ -63,6 +66,11 @@ type CiliumGenerator struct {
 	Writer io.WriteCloser
 }
 
+// SWIFTGenerator generates the Azure CNI conflist for the SWIFT scenario
+type SWIFTGenerator struct {
+	Writer io.WriteCloser
+}
+
 func (v *V4OverlayGenerator) Close() error {
 	if err := v.Writer.Close(); err != nil {
 		return errors.Wrap(err, "error closing generator")
@@ -94,3 +102,11 @@ func (v *CiliumGenerator) Close() error {
 
 	return nil
 }
+
+func (v *SWIFTGenerator) Close() error {
+	if err := v.Writer.Close(); err != nil {
+		return errors.Wrap(err, "error closing generator")
+	}
+
+	return nil
+}

cns/cniconflist/generator_linux.go

@@ -133,3 +133,31 @@ func (v *CiliumGenerator) Generate() error {
 
 	return nil
 }
+
+// Generate writes the CNI conflist to the Generator's output stream
+func (v *SWIFTGenerator) Generate() error {
+	conflist := cniConflist{
+		CNIVersion: azurecniVersion,
+		Name:       azureName,
+		Plugins: []any{
+			cni.NetworkConfig{
+				Type:              azureType,
+				Mode:              cninet.OpModeTransparent,
+				ExecutionMode:     string(util.V4Swift),
+				IPsToRouteViaHost: []string{nodeLocalDNSIP},
+				IPAM: cni.IPAM{
+					Type: network.AzureCNS,
+				},
+			},
+			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
+}

cns/cniconflist/generator_linux_test.go

@@ -77,6 +77,21 @@ func TestGenerateCiliumConflist(t *testing.T) {
 	assert.Equal(t, removeNewLines(fixtureBytes), removeNewLines(buffer.Bytes()))
 }
 
+func TestGenerateSWIFTConflist(t *testing.T) {
+	fixture := "testdata/fixtures/azure-linux-swift.conflist"
+
+	buffer := new(bytes.Buffer)
+	g := cniconflist.SWIFTGenerator{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()))
+}
+
 // removeNewLines will remove the newlines and carriage returns from the byte slice
 func removeNewLines(b []byte) []byte {
 	var bb []byte //nolint:prealloc // can't prealloc since we don't know how many bytes will get removed

cns/cniconflist/generator_windows.go

@@ -21,3 +21,7 @@ func (v *OverlayGenerator) Generate() error {
 func (v *CiliumGenerator) Generate() error {
 	return errNotImplemented
 }
+
+func (v *SWIFTGenerator) Generate() error {
+	return errNotImplemented
+}

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

@@ -0,0 +1,29 @@
+{
+	"cniVersion": "0.3.0",
+	"name": "azure",
+	"plugins": [
+		{
+			"type": "azure-vnet",
+			"mode": "transparent",
+			"ipsToRouteViaHost": [
+				"169.254.20.10"
+			],
+			"executionMode": "v4swift",
+			"ipam": {
+				"type": "azure-cns"
+			},
+			"dns": {},
+			"runtimeConfig": {
+				"dns": {}
+			},
+			"windowsSettings": {}
+		},
+		{
+			"type": "portmap",
+			"capabilities": {
+				"portMappings": true
+			},
+			"snat": true
+		}
+	]
+}

cns/service/main.go

@@ -96,6 +96,7 @@ const (
 	scenarioDualStackOverlay cniConflistScenario = "dualStackOverlay"
 	scenarioOverlay          cniConflistScenario = "overlay"
 	scenarioCilium           cniConflistScenario = "cilium"
+	scenarioSWIFT            cniConflistScenario = "swift"
 )
 
 var (
@@ -550,6 +551,8 @@ func main() {
 			conflistGenerator = &cniconflist.OverlayGenerator{Writer: writer}
 		case scenarioCilium:
 			conflistGenerator = &cniconflist.CiliumGenerator{Writer: writer}
+		case scenarioSWIFT:
+			conflistGenerator = &cniconflist.SWIFTGenerator{Writer: writer}
 		default:
 			logger.Errorf("unable to generate cni conflist for unknown scenario: %s", scenario)
 			os.Exit(1)