xds: Remove v3Support environment variable

xds/internal/client/bootstrap/bootstrap.go

@@ -258,14 +258,10 @@ func NewConfig() (*Config, error) {
 		return nil, fmt.Errorf("xds: Required field %q doesn't contain valid value in bootstrap %s", "xds_servers.channel_creds", jsonData["xds_servers"])
 	}
 
-	// We end up using v3 transport protocol version only if the following
-	// conditions are met:
-	// 1. Server supports v3, indicated by the presence of "xds_v3" in
-	//    server_features.
-	// 2. Environment variable "GRPC_XDS_EXPERIMENTAL_V3_SUPPORT" is set to
-	//    true.
-	// The default value of the enum type "version.TransportAPI" is v2.
-	if env.V3Support && serverSupportsV3 {
+	// We end up using v3 transport protocol version only if the server supports
+	// v3, indicated by the presence of "xds_v3" in server_features. The default
+	// value of the enum type "version.TransportAPI" is v2.
+	if serverSupportsV3 {
 		config.TransportAPI = version.TransportV3
 	}
 

xds/internal/client/bootstrap/bootstrap_test.go

@@ -430,43 +430,10 @@ func TestNewConfigV2ProtoSuccess(t *testing.T) {
 	}
 }
 
-// TestNewConfigV3SupportNotEnabledOnClient verifies bootstrap functionality
-// when the GRPC_XDS_EXPERIMENTAL_V3_SUPPORT environment variable is not enabled
-// on the client. In this case, whether the server supports v3 or not, the
-// client will end up using v2.
-func TestNewConfigV3SupportNotEnabledOnClient(t *testing.T) {
-	origV3Support := env.V3Support
-	env.V3Support = false
-	defer func() { env.V3Support = origV3Support }()
-
-	cancel := setupBootstrapOverride(v3BootstrapFileMap)
-	defer cancel()
-
-	tests := []struct {
-		name       string
-		wantConfig *Config
-	}{
-		{"serverDoesNotSupportsV3", nonNilCredsConfigV2},
-		{"serverSupportsV3", nonNilCredsConfigV2},
-	}
-
-	for _, test := range tests {
-		t.Run(test.name, func(t *testing.T) {
-			testNewConfigWithFileNameEnv(t, test.name, false, test.wantConfig)
-			testNewConfigWithFileContentEnv(t, test.name, false, test.wantConfig)
-		})
-	}
-}
-
-// TestNewConfigV3SupportEnabledOnClient verifies bootstrap functionality when
-// the GRPC_XDS_EXPERIMENTAL_V3_SUPPORT environment variable is enabled on the
-// client. Here the client ends up using v2 or v3 based on what the server
-// supports.
-func TestNewConfigV3SupportEnabledOnClient(t *testing.T) {
-	origV3Support := env.V3Support
-	env.V3Support = true
-	defer func() { env.V3Support = origV3Support }()
-
+// TestNewConfigV3Support verifies bootstrap functionality involving support for
+// the xDS v3 transport protocol. Here the client ends up using v2 or v3 based
+// on what the server supports.
+func TestNewConfigV3Support(t *testing.T) {
 	cancel := setupBootstrapOverride(v3BootstrapFileMap)
 	defer cancel()
 
@@ -486,15 +453,12 @@ func TestNewConfigV3SupportEnabledOnClient(t *testing.T) {
 	}
 }
 
-// TestNewConfigBootstrapEnvPriority tests that the two env variables are read in correct priority
+// TestNewConfigBootstrapEnvPriority tests that the two env variables are read
+// in correct priority.
 //
 // the case where the bootstrap file
 // environment variable is not set.
 func TestNewConfigBootstrapEnvPriority(t *testing.T) {
-	origV3Support := env.V3Support
-	env.V3Support = true
-	defer func() { env.V3Support = origV3Support }()
-
 	oldFileReadFunc := bootstrapFileReadFunc
 	bootstrapFileReadFunc = func(filename string) ([]byte, error) {
 		return fileReadFromFileMap(v2BootstrapFileMap, filename)
@@ -702,10 +666,6 @@ func TestNewConfigWithCertificateProviders(t *testing.T) {
 		t.Fatalf("config parsing for plugin %q failed: %v", fakeCertProviderName, err)
 	}
 
-	origV3Support := env.V3Support
-	env.V3Support = true
-	defer func() { env.V3Support = origV3Support }()
-
 	cancel := setupBootstrapOverride(bootstrapFileMap)
 	defer cancel()
 

xds/internal/env/env.go

@@ -38,7 +38,6 @@ const (
 	//
 	// When both bootstrap FileName and FileContent are set, FileName is used.
 	BootstrapFileContentEnv   = "GRPC_XDS_BOOTSTRAP_CONFIG"
-	xdsV3SupportEnv           = "GRPC_XDS_EXPERIMENTAL_V3_SUPPORT"
 	circuitBreakingSupportEnv = "GRPC_XDS_EXPERIMENTAL_CIRCUIT_BREAKING"
 	timeoutSupportEnv         = "GRPC_XDS_EXPERIMENTAL_ENABLE_TIMEOUT"
 )
@@ -56,10 +55,6 @@ var (
 	//
 	// When both bootstrap FileName and FileContent are set, FileName is used.
 	BootstrapFileContent = os.Getenv(BootstrapFileContentEnv)
-	// V3Support indicates whether xDS v3 API support is enabled, which can be
-	// done by setting the environment variable
-	// "GRPC_XDS_EXPERIMENTAL_V3_SUPPORT" to "true".
-	V3Support = strings.EqualFold(os.Getenv(xdsV3SupportEnv), "true")
 	// CircuitBreakingSupport indicates whether circuit breaking support is
 	// enabled, which can be done by setting the environment variable
 	// "GRPC_XDS_EXPERIMENTAL_CIRCUIT_BREAKING" to "true".

xds/internal/test/xds_server_integration_test.go

@@ -50,7 +50,6 @@ import (
 	testpb "google.golang.org/grpc/test/grpc_testing"
 	"google.golang.org/grpc/testdata"
 	"google.golang.org/grpc/xds"
-	"google.golang.org/grpc/xds/internal/env"
 	"google.golang.org/grpc/xds/internal/testutils"
 	"google.golang.org/grpc/xds/internal/testutils/e2e"
 	"google.golang.org/grpc/xds/internal/version"
@@ -136,10 +135,6 @@ func createClientTLSCredentials(t *testing.T) credentials.TransportCredentials {
 func commonSetup(t *testing.T) (*e2e.ManagementServer, string, net.Listener, func()) {
 	t.Helper()
 
-	// Turn on xDS V3 support.
-	origV3Support := env.V3Support
-	env.V3Support = true
-
 	// Spin up a xDS management server on a local port.
 	nodeID := uuid.New().String()
 	fs, err := e2e.StartManagementServer()
@@ -189,7 +184,6 @@ func commonSetup(t *testing.T) (*e2e.ManagementServer, string, net.Listener, fun
 	}()
 
 	return fs, nodeID, lis, func() {
-		env.V3Support = origV3Support
 		fs.Stop()
 		bootstrapCleanup()
 		server.Stop()