unix socket support

Signed-off-by: Boris Rybalkin <ribalkin@gmail.com>

.gitignore

@@ -4,3 +4,4 @@ node_modules
 # Go workspaces
 go.work
 go.work.sum
+.idea

sync2/client.go

@@ -4,9 +4,11 @@ import (
 	"context"
 	"encoding/json"
 	"fmt"
-	"io/ioutil"
+	"io"
+	"net"
 	"net/http"
 	"net/url"
+	"strings"
 	"time"
 
 	"go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp"
@@ -39,16 +41,30 @@ type HTTPClient struct {
 }
 
 func NewHTTPClient(shortTimeout, longTimeout time.Duration, destHomeServer string) *HTTPClient {
+	baseUrl := destHomeServer
+	if strings.HasPrefix(destHomeServer, "/") {
+	     baseUrl = "http://unix"
+	}
+
 	return &HTTPClient{
-		LongTimeoutClient: &http.Client{
+		LongTimeoutClient: newClient(longTimeout, destHomeServer),
-			Timeout:   longTimeout,
+		Client:            newClient(shortTimeout, destHomeServer),
-			Transport: otelhttp.NewTransport(http.DefaultTransport),
+		DestinationServer: baseUrl,
+	}
+}
+
+func newClient(timeout time.Duration, destHomeServer string) *http.Client {
+	transport := http.DefaultTransport
+	if strings.HasPrefix(destHomeServer, "/") {
+		transport = &http.Transport{
+			DialContext: func(_ context.Context, _, _ string) (net.Conn, error) {
+				return net.Dial("unix", destHomeServer)
 			},
-		Client: &http.Client{
+		}
-			Timeout:   shortTimeout,
+	}
-			Transport: otelhttp.NewTransport(http.DefaultTransport),
+	return &http.Client{
-		},
+		Timeout:   timeout,
-		DestinationServer: destHomeServer,
+		Transport: otelhttp.NewTransport(transport),
 	}
 }
 
@@ -66,7 +82,7 @@ func (v *HTTPClient) Versions(ctx context.Context) ([]string, error) {
 		return nil, fmt.Errorf("/versions returned HTTP %d", res.StatusCode)
 	}
 	defer res.Body.Close()
-	body, err := ioutil.ReadAll(res.Body)
+	body, err := io.ReadAll(res.Body)
 	if err != nil {
 		return nil, err
 	}
@@ -99,7 +115,7 @@ func (v *HTTPClient) WhoAmI(ctx context.Context, accessToken string) (string, st
 		return "", "", fmt.Errorf("/whoami returned HTTP %d", res.StatusCode)
 	}
 	defer res.Body.Close()
-	body, err := ioutil.ReadAll(res.Body)
+	body, err := io.ReadAll(res.Body)
 	if err != nil {
 		return "", "", err
 	}

v3.go

@@ -4,7 +4,10 @@ import (
 	"context"
 	"embed"
 	"encoding/json"
+	"errors"
 	"fmt"
+	"io/fs"
+	"net"
 	"net/http"
 	"os"
 	"strings"
@@ -216,6 +219,11 @@ func RunSyncV3Server(h http.Handler, bindAddr, destV2Server, tlsCert, tlsKey str
 
 	// Block forever
 	var err error
+	if strings.HasPrefix(bindAddr, "/") {
+		logger.Info().Msgf("listening on unix socket %s", bindAddr)
+		listener := unixSocketListener(bindAddr)
+		err = http.Serve(listener, srv)
+	} else {
 		if tlsCert != "" && tlsKey != "" {
 			logger.Info().Msgf("listening TLS on %s", bindAddr)
 			err = http.ListenAndServeTLS(bindAddr, tlsCert, tlsKey, srv)
@@ -223,6 +231,7 @@ func RunSyncV3Server(h http.Handler, bindAddr, destV2Server, tlsCert, tlsKey str
 			logger.Info().Msgf("listening on %s", bindAddr)
 			err = http.ListenAndServe(bindAddr, srv)
 		}
+	}
 	if err != nil {
 		sentry.CaptureException(err)
 		// TODO: Fatal() calls os.Exit. Will that give time for sentry.Flush() to run?
@@ -230,6 +239,22 @@ func RunSyncV3Server(h http.Handler, bindAddr, destV2Server, tlsCert, tlsKey str
 	}
 }
 
+func unixSocketListener(bindAddr string) net.Listener {
+	err := os.Remove(bindAddr)
+	if err != nil && !errors.Is(err, fs.ErrNotExist) {
+		logger.Fatal().Err(err).Msg("failed to remove existing unix socket")
+	}
+	listener, err := net.Listen("unix", bindAddr)
+	if err != nil {
+		logger.Fatal().Err(err).Msg("failed to serve unix socket")
+	}
+	err = os.Chmod(bindAddr, 0755)
+	if err != nil {
+		logger.Fatal().Err(err).Msg("failed to set unix socket permissions")
+	}
+	return listener
+}
+
 type HandlerError struct {
 	StatusCode int
 	Err        error