Add Support for Unix Socket endpoints

CHANGELOG/CHANGELOG-3.7.md

@@ -1,5 +1,4 @@
 
-
 Previous change logs can be found at [CHANGELOG-3.6](https://github.com/etcd-io/etcd/blob/main/CHANGELOG/CHANGELOG-3.6.md).
 
 ---
@@ -13,6 +12,7 @@ Previous change logs can be found at [CHANGELOG-3.6](https://github.com/etcd-io/
 ### etcd server
 
 - [Update go.opentelemetry.io/contrib/instrumentation/google.golang.org/grpc/otelgrpc to v0.61.0 and replaced the deprecated `UnaryServerInterceptor` and `StreamServerInterceptor` with `NewServerHandler`](https://github.com/etcd-io/etcd/pull/20017)
+- [Add Support for Unix Socket endpoints](https://github.com/etcd-io/etcd/pull/19760)
 
 ### Package `pkg`
 

server/embed/config.go

@@ -963,7 +963,7 @@
 	}
 	if err := checkHostURLs(cfg.AdvertiseClientUrls); err != nil {
 		addrs := cfg.getAdvertiseClientURLs()
-		return fmt.Errorf(`--advertise-client-urls %q must be "host:port" (%w)`, strings.Join(addrs, ","), err)
+		return fmt.Errorf(`--advertise-client-urls %q must be in the format "host:port", "unix:/path/to/socket" or "unixs:/path/to/socket" (%w)`, strings.Join(addrs, ","), err)
 	}
 	// Check if conflicting flags are passed.
 	nSet := 0
@@ -1355,6 +1355,9 @@
 
 func checkHostURLs(urls []url.URL) error {
 	for _, url := range urls {
+		if url.Scheme == "unix" || url.Scheme == "unixs" {
+			continue
+		}
 		host, _, err := net.SplitHostPort(url.Host)
 		if err != nil {
 			return err

server/embed/config_test.go

@@ -784,3 +784,66 @@ func TestMatchNewConfigAddFlags(t *testing.T) {
 		t.Errorf("Diff: %s", diff)
 	}
 }
+
+func TestCheckHostURLs(t *testing.T) {
+	tests := []struct {
+		name    string
+		urls    []url.URL
+		wantErr bool
+	}{
+		{
+			name: "valid HTTP URLs",
+			urls: []url.URL{
+				{Scheme: "http", Host: "127.0.0.1:2379"},
+				{Scheme: "http", Host: "localhost:2379"},
+			},
+			wantErr: false,
+		},
+		{
+			name: "valid HTTPS URLs",
+			urls: []url.URL{
+				{Scheme: "https", Host: "127.0.0.1:2379"},
+				{Scheme: "https", Host: "localhost:2379"},
+			},
+			wantErr: false,
+		},
+		{
+			name: "valid Unix socket URLs",
+			urls: []url.URL{
+				{Scheme: "unix", Host: "", Path: "/tmp/etcd.sock"},
+				{Scheme: "unixs", Host: "", Path: "/tmp/etcd-secure.sock"},
+			},
+			wantErr: false,
+		},
+		{
+			name: "empty host in URL",
+			urls: []url.URL{
+				{Scheme: "http", Host: ""},
+			},
+			wantErr: true,
+		},
+		{
+			name: "invalid host format",
+			urls: []url.URL{
+				{Scheme: "http", Host: "invalid_host"},
+			},
+			wantErr: true,
+		},
+		{
+			name: "missing port in host",
+			urls: []url.URL{
+				{Scheme: "http", Host: "127.0.0.1"},
+			},
+			wantErr: true,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			err := checkHostURLs(tt.urls)
+			if (err != nil) != tt.wantErr {
+				t.Errorf("checkHostURLs() error = %v, wantErr %v", err, tt.wantErr)
+			}
+		})
+	}
+}

tests/e2e/etcd_config_test.go

@@ -735,3 +735,55 @@ func TestV2DeprecationEnforceDefaultValue(t *testing.T) {
 		})
 	}
 }
+
+func TestEtcdAdvertiseClientUnix(t *testing.T) {
+	e2e.SkipInShortMode(t)
+
+	// Create a temporary directory for the data directory
+	dataDir := t.TempDir()
+	socketDir := t.TempDir()
+	unixSocket := fmt.Sprintf("unix://%s/etcd-client.sock", socketDir)
+
+	// Start etcd with AdvertiseClientUrls set to a unix socket
+	proc, err := e2e.SpawnCmd(
+		[]string{
+			e2e.BinPath.Etcd,
+			"--data-dir", dataDir,
+			"--name", "etcd1",
+			"--listen-client-urls", unixSocket,
+			"--advertise-client-urls", unixSocket,
+		}, nil,
+	)
+	require.NoError(t, err)
+	defer func() {
+		_ = proc.Stop()
+		_ = proc.Close()
+	}()
+
+	// Wait for the process to be ready
+	require.NoError(t, e2e.WaitReadyExpectProc(t.Context(), proc, e2e.EtcdServerReadyLines))
+
+	// Write a key/value pair using etcdctl with unix socket
+	putArgs := []string{
+		e2e.BinPath.Etcdctl,
+		"--endpoints", unixSocket,
+		"put", "foo", "bar",
+	}
+	putProc, err := e2e.SpawnCmd(putArgs, nil)
+	require.NoError(t, err)
+	require.NoError(t, e2e.WaitReadyExpectProc(t.Context(), putProc, []string{"OK"}))
+	require.NoError(t, putProc.Stop())
+	_ = putProc.Close()
+
+	// Read the key back using etcdctl with unix socket
+	getArgs := []string{
+		e2e.BinPath.Etcdctl,
+		"--endpoints", unixSocket,
+		"get", "foo",
+	}
+	getProc, err := e2e.SpawnCmd(getArgs, nil)
+	require.NoError(t, err)
+	require.NoError(t, e2e.WaitReadyExpectProc(t.Context(), getProc, []string{"foo", "bar"}))
+	require.NoError(t, getProc.Stop())
+	_ = getProc.Close()
+}