fix: detect Docker host from context when DOCKER_HOST is not set

pkg/docker/docker_client.go

@@ -84,28 +84,33 @@ func NewClient(defaultHost string) (dc DockerClient, dockerHostInRemote string,
 	hostKeyCallback := fnssh.NewHostKeyCbk()
 
 	if dockerHost == "" {
-		_url, err = url.Parse(defaultHost)
-		if err != nil {
-			return
-		}
-		_, err = os.Stat(_url.Path)
-		switch {
-		case err == nil:
-			dockerHost = defaultHost
-		case err != nil && !os.IsNotExist(err):
-			return
-		case os.IsNotExist(err) && podmanPresent():
-			if runtime.GOOS == "linux" {
-				// on Linux: spawn temporary podman service
-				rawClient, dockerHostInRemote, err = newClientWithPodmanService()
+		// Try to get Docker host from current context
+		if contextHost := getDockerContextHost(); contextHost != "" {
+			dockerHost = contextHost
+		} else {
+			_url, err = url.Parse(defaultHost)
+			if err != nil {
+				return
+			}
+			_, err = os.Stat(_url.Path)
+			switch {
+			case err == nil:
+				dockerHost = defaultHost
+			case err != nil && !os.IsNotExist(err):
 				return
-			} else {
-				// on non-Linux: try to use connection to podman machine
-				dh, dhid := tryGetPodmanRemoteConn()
-				if dh != "" {
-					dockerHost, dockerHostSSHIdentity = dh, dhid
-					hostKeyCallback = func(hostPort string, pubKey ssh.PublicKey) error {
-						return nil
+			case os.IsNotExist(err) && podmanPresent():
+				if runtime.GOOS == "linux" {
+					// on Linux: spawn temporary podman service
+					rawClient, dockerHostInRemote, err = newClientWithPodmanService()
+					return
+				} else {
+					// on non-Linux: try to use connection to podman machine
+					dh, dhid := tryGetPodmanRemoteConn()
+					if dh != "" {
+						dockerHost, dockerHostSSHIdentity = dh, dhid
+						hostKeyCallback = func(hostPort string, pubKey ssh.PublicKey) error {
+							return nil
+						}
 					}
 				}
 			}
@@ -284,6 +289,45 @@ func podmanPresent() bool {
 	return err == nil
 }
 
+// getDockerContextHost tries to get the Docker host from the current Docker context.
+// This is useful for Docker Desktop which uses context-specific sockets.
+// Returns empty string if unable to determine the context host.
+func getDockerContextHost() string {
+	// Check if docker CLI is available
+	dockerPath, err := exec.LookPath("docker")
+	if err != nil {
+		return ""
+	}
+
+	// Run 'docker context inspect' to get current context details
+	cmd := exec.Command(dockerPath, "context", "inspect")
+	out, err := cmd.CombinedOutput()
+	if err != nil {
+		return ""
+	}
+
+	// Parse the JSON output
+	var contexts []struct {
+		Name      string
+		Endpoints struct {
+			Docker struct {
+				Host string `json:"Host"`
+			} `json:"docker"`
+		} `json:"Endpoints"`
+	}
+
+	if err := json.Unmarshal(out, &contexts); err != nil {
+		return ""
+	}
+
+	// Return the host from the first (current) context
+	if len(contexts) > 0 && contexts[0].Endpoints.Docker.Host != "" {
+		return contexts[0].Endpoints.Docker.Host
+	}
+
+	return ""
+}
+
 type clientWithAdditionalCleanup struct {
 	client.APIClient
 	cleanUp func()

pkg/docker/docker_client_test.go

@@ -127,3 +127,36 @@ func startMockDaemonUnix(t *testing.T, sock string) {
 	}
 	startMockDaemon(t, l)
 }
+
+// TestNewClient_DockerContext tests that Docker context is properly detected
+// when DOCKER_HOST is not set
+func TestNewClient_DockerContext(t *testing.T) {
+	if runtime.GOOS == "windows" {
+		t.Skip("Skipping Docker context test on Windows")
+	}
+
+	// This test requires docker CLI to be available
+	// If not available, skip the test
+	ctx, cancel := context.WithTimeout(t.Context(), time.Second*5)
+	defer cancel()
+
+	// Unset DOCKER_HOST to force context detection
+	t.Setenv("DOCKER_HOST", "")
+
+	// Try to create a client - it should use Docker context if available
+	dockerClient, _, err := docker.NewClient(client.DefaultDockerHost)
+	if err != nil {
+		// If docker is not available or not running, skip the test
+		if err == docker.ErrNoDocker {
+			t.Skip("Docker not available, skipping context detection test")
+		}
+		t.Fatalf("Failed to create Docker client: %v", err)
+	}
+	defer dockerClient.Close()
+
+	// Try to ping the daemon to verify the connection works
+	_, err = dockerClient.Ping(ctx, client.PingOptions{})
+	if err != nil {
+		t.Errorf("Failed to ping Docker daemon via context: %v", err)
+	}
+}