refactor: removed gw command (#627)

The separate `gw` command has been removed and its functionality
incorporated into the `run` command. The HTTP gateway is then enabled
using `--enable-http`.

NOTE: the code to start the HTTP gateway remains the same. We will need
to refactor it in the future to take into account the the TLS flags.

Signed-off-by: Richard Case <richard.case@outlook.com>
Co-authored-by: Balazs Nadasdi <balazs@weave.works>

go.mod

@@ -55,6 +55,7 @@ require (
 	github.com/urfave/cli/v2 v2.24.4
 	github.com/weaveworks-liquidmetal/flintlock/api v0.0.0-20230211152005-2177e42d0ee6
 	github.com/weaveworks-liquidmetal/flintlock/client v0.0.0-20230211152005-2177e42d0ee6
+	github.com/grpc-ecosystem/grpc-gateway v1.16.0
 	github.com/yitsushi/file-tailor v1.0.0
 	gopkg.in/yaml.v2 v2.4.0
 	sigs.k8s.io/yaml v1.3.0

internal/command/flags/flags.go

@@ -55,10 +55,10 @@ func AddGRPCServerFlagsToCommand(cmd *cobra.Command, cfg *config.Config) {
 
 // AddGWServerFlagsToCommand will add gRPC HTTP gateway flags to the supplied command.
 func AddGWServerFlagsToCommand(cmd *cobra.Command, cfg *config.Config) {
-	cmd.Flags().StringVar(&cfg.GRPCAPIEndpoint,
-		grpcEndpointFlag,
-		defaults.GRPCAPIEndpoint,
-		"The address of the gRPC server to act as a gateway for.")
+	cmd.Flags().BoolVar(&cfg.EnableHTTPGateway,
+		"enable-http",
+		false,
+		"Should the API be exposed via HTTP.")
 
 	cmd.Flags().StringVar(&cfg.HTTPAPIEndpoint,
 		httpEndpointFlag,

internal/command/root.go

@@ -6,7 +6,7 @@ import (
 
 	"github.com/spf13/cobra"
 	"github.com/spf13/viper"
-	"github.com/weaveworks-liquidmetal/flintlock/internal/command/gw"
+
 	"github.com/weaveworks-liquidmetal/flintlock/internal/command/run"
 	"github.com/weaveworks-liquidmetal/flintlock/internal/config"
 	"github.com/weaveworks-liquidmetal/flintlock/internal/version"
@@ -72,9 +72,6 @@ func addRootSubCommands(cmd *cobra.Command, cfg *config.Config) error {
 	cmd.AddCommand(runCmd)
 	cmd.AddCommand(versionCommand())
 
-	gwCmd := gw.NewCommand(cfg)
-	cmd.AddCommand(gwCmd)
-
 	return nil
 }
 

internal/command/run/run.go

@@ -16,6 +16,7 @@ import (
 	grpc_mw "github.com/grpc-ecosystem/go-grpc-middleware"
 	grpc_auth "github.com/grpc-ecosystem/go-grpc-middleware/auth"
 	grpc_prometheus "github.com/grpc-ecosystem/go-grpc-prometheus"
+	"github.com/grpc-ecosystem/grpc-gateway/v2/runtime"
 	"github.com/prometheus/client_golang/prometheus/promhttp"
 	"github.com/spf13/cobra"
 	mvmv1 "github.com/weaveworks-liquidmetal/flintlock/api/services/microvm/v1alpha1"
@@ -27,6 +28,7 @@ import (
 	"github.com/weaveworks-liquidmetal/flintlock/pkg/flags"
 	"github.com/weaveworks-liquidmetal/flintlock/pkg/log"
 	"google.golang.org/grpc"
+	"google.golang.org/grpc/credentials/insecure"
 	"google.golang.org/grpc/reflection"
 )
 
@@ -63,6 +65,7 @@ func NewCommand(cfg *config.Config) (*cobra.Command, error) {
 	cmdflags.AddContainerDFlagsToCommand(cmd, cfg)
 	cmdflags.AddFirecrackerFlagsToCommand(cmd, cfg)
 	cmdflags.AddDebugFlagsToCommand(cmd, cfg)
+	cmdflags.AddGWServerFlagsToCommand(cmd, cfg)
 
 	if err := cmdflags.AddNetworkFlagsToCommand(cmd, cfg); err != nil {
 		return nil, fmt.Errorf("adding network flags to run command: %w", err)
@@ -109,6 +112,17 @@ func runServer(ctx context.Context, cfg *config.Config) error {
 		}()
 	}
 
+	if cfg.EnableHTTPGateway {
+		wg.Add(1)
+
+		go func() {
+			defer wg.Done()
+			if err := serveHTTP(ctx, cfg); err != nil {
+				logger.Errorf("failed serving http api: %v", err)
+			}
+		}()
+	}
+
 	if !cfg.DisableReconcile {
 		wg.Add(1)
 
@@ -271,3 +285,39 @@ func runPProf(ctx context.Context, cfg *config.Config) error {
 
 	return nil
 }
+
+func serveHTTP(ctx context.Context, cfg *config.Config) error {
+	logger := log.GetLogger(ctx)
+	mux := runtime.NewServeMux()
+
+	opts := []grpc.DialOption{
+		grpc.WithTransportCredentials(insecure.NewCredentials()),
+	}
+
+	if err := mvmv1.RegisterMicroVMHandlerFromEndpoint(ctx, mux, cfg.GRPCAPIEndpoint, opts); err != nil {
+		return fmt.Errorf("could not register microvm server: %w", err)
+	}
+
+	server := &http.Server{
+		Addr:    cfg.HTTPAPIEndpoint,
+		Handler: mux,
+	}
+
+	go func() {
+		<-ctx.Done()
+		logger.Infof("shutting down the http gateway server")
+
+		//nolint: contextcheck // Intentional.
+		if err := server.Shutdown(context.Background()); err != nil {
+			logger.Errorf("failed to shutdown http gateway server: %v", err)
+		}
+	}()
+
+	logger.Debugf("starting http server listening on endpoint %s", cfg.HTTPAPIEndpoint)
+
+	if err := server.ListenAndServe(); err != nil {
+		return fmt.Errorf("listening and serving http api: %w", err)
+	}
+
+	return nil
+}

internal/config/config.go

@@ -16,6 +16,8 @@ type Config struct {
 	GRPCAPIEndpoint string
 	// HTTPAPIEndpoint is the endpoint for the HTTP proxy for the gRPC service
 	HTTPAPIEndpoint string
+	// EnableHTTPGateway indicates that the HTTP gateway should be started
+	EnableHTTPGateway bool
 	// FirecrackerBin is the firecracker binary to use.
 	FirecrackerBin string
 	// FirecrackerDetatch indicates if the child firecracker processes should be detached from their parent.