Use Docker CLI socket from the User's home directory

We should not rely on having a global path for the Docker CLI socket. On
macOS this forces Docker Desktop to access directories which require
raised privileges. Whereas on Linux we do not create sockets in that
location at all, currently. So look for the Docker CLI socket in the
User's home directory.

Signed-off-by: Piotr Stankiewicz <piotr.stankiewicz@docker.com>

cli/metrics/conn_darwin.go

@@ -0,0 +1,43 @@
+//go:build darwin
+// +build darwin
+
+/*
+   Copyright 2020 Docker Compose CLI authors
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package metrics
+
+import (
+	"net"
+	"path/filepath"
+
+	"github.com/docker/docker/pkg/homedir"
+)
+
+var (
+	socket = "/var/run/docker-cli.sock"
+)
+
+func init() {
+	// Attempt to retrieve the Docker CLI socket for the current user.
+	if home := homedir.Get(); home != "" {
+		socket = filepath.Join(home, "/Library/Containers/com.docker.docker/Data/docker-cli.sock")
+	} // else: On macOS Docker Desktop creates symlinks in /var/run, so fall back to the old default.
+	overrideSocket() // nop, unless built for e2e testing
+}
+
+func conn() (net.Conn, error) {
+	return net.Dial("unix", socket)
+}

cli/metrics/conn_e2e.go

@@ -1,3 +1,4 @@
+//go:build e2e
 // +build e2e
 
 /*
@@ -22,7 +23,7 @@ import (
 	"os"
 )
 
-func init() {
+func overrideSocket() {
 	testSocket, defined := os.LookupEnv("TEST_METRICS_SOCKET")
 	if defined {
 		socket = testSocket

cli/metrics/conn_note2e.go

@@ -0,0 +1,23 @@
+//go:build !e2e
+// +build !e2e
+
+/*
+   Copyright 2020 Docker Compose CLI authors
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package metrics
+
+func overrideSocket() {
+}

cli/metrics/conn_other.go

@@ -1,4 +1,5 @@
-// +build !windows
+//go:build !windows,!darwin
+// +build !windows,!darwin
 
 /*
    Copyright 2020 Docker Compose CLI authors
@@ -18,12 +19,25 @@
 
 package metrics
 
-import "net"
+import (
+	"net"
+	"path/filepath"
+
+	"github.com/docker/docker/pkg/homedir"
+)
 
 var (
-	socket = "/var/run/docker-cli.sock"
+	socket = ""
 )
 
+func init() {
+	// Attempt to retrieve the Docker CLI socket for the current user.
+	if home := homedir.Get(); home != "" {
+		socket = filepath.Join(home, ".docker/desktop/docker-cli.sock")
+	} // else: On Linux we don't expect to have a global CLI socket, so leave it empty and let connections fail.
+	overrideSocket() // nop, unless built for e2e testing
+}
+
 func conn() (net.Conn, error) {
 	return net.Dial("unix", socket)
 }

cli/metrics/conn_windows.go

@@ -1,3 +1,4 @@
+//go:build windows
 // +build windows
 
 /*
@@ -30,6 +31,10 @@ var (
 	socket = `\\.\pipe\docker_cli`
 )
 
+func init() {
+	overrideSocket() // nop, unless built for e2e testing
+}
+
 func conn() (net.Conn, error) {
 	if strings.HasPrefix(socket, `\\.\pipe\`) {
 		timeout := 200 * time.Millisecond