Improve engine type detection

In some cases we may end up misidentifying the underlying engine type.
Improve the logic for doing that to make it impossible to identify DD on
windows or macos as plain moby.

Signed-off-by: Piotr Stankiewicz <[email protected]>

Author: Piotr Stankiewicz

desktop/context.go

@@ -17,6 +17,7 @@ import (
 	"github.com/docker/model-cli/pkg/standalone"
 	"github.com/docker/model-cli/pkg/types"
 	"github.com/docker/model-runner/pkg/inference"
+	"github.com/pkg/errors"
 )
 
 // isDesktopContext returns true if the CLI instance points to a Docker Desktop
@@ -115,8 +116,12 @@ func DetectContext(ctx context.Context, cli *command.DockerCli) (*ModelRunnerCon
 	treatDesktopAsMoby := os.Getenv("_MODEL_RUNNER_TREAT_DESKTOP_AS_MOBY") == "1"
 
 	// Detect the associated engine type.
-	kind := types.ModelRunnerEngineKindMoby
-	if modelRunnerHost != "" {
+	kind := types.ModelRunnerEngineKindUnknown
+	if runtime.GOOS == "linux" {
+		kind = types.ModelRunnerEngineKindMoby
+	}
+
+	if modelRunnerHost != "" && kind == types.ModelRunnerEngineKindMoby {
 		kind = types.ModelRunnerEngineKindMobyManual
 	} else if isDesktopContext(ctx, cli) {
 		kind = types.ModelRunnerEngineKindDesktop
@@ -127,6 +132,10 @@ func DetectContext(ctx context.Context, cli *command.DockerCli) (*ModelRunnerCon
 		kind = types.ModelRunnerEngineKindCloud
 	}
 
+	if kind == types.ModelRunnerEngineKindUnknown {
+		return nil, errors.New("unable to determine docker engine type")
+	}
+
 	// Compute the URL prefix based on the associated engine kind.
 	var rawURLPrefix string
 	if kind == types.ModelRunnerEngineKindMoby {

pkg/types/engine.go

@@ -5,9 +5,12 @@ package types
 type ModelRunnerEngineKind uint8
 
 const (
+	// ModelRunnerEngineKindUnknown represents an engine whose type can not be
+	// determined.
+	ModelRunnerEngineKindUnknown ModelRunnerEngineKind = iota
 	// ModelRunnerEngineKindMoby represents a non-Desktop/Cloud engine on which
 	// the Model CLI command is responsible for managing a Model Runner.
-	ModelRunnerEngineKindMoby ModelRunnerEngineKind = iota
+	ModelRunnerEngineKindMoby
 	// ModelRunnerEngineKindMobyManual represents a non-Desktop/Cloud engine
 	// that's explicitly targeted by a MODEL_RUNNER_HOST environment variable on
 	// which the user is responsible for managing a Model Runner.