[registry-facade] Add desktop_ide_ref

components/registry-facade-api/imagespec.proto

@@ -12,6 +12,8 @@ message ImageSpec {
     string ide_ref = 2;
     // content_layer describe the last few layers which provide the workspace's content
     repeated ContentLayer content_layer = 3;
+    // desktop_ide_ref point to an image denotign the desktop IDE to use
+    string desktop_ide_ref = 4;
 }
 
 // ContentLayer is a layer that provides a workspace's content

components/registry-facade/pkg/registry/layersource.go

@@ -394,6 +394,9 @@ func (src *SpecMappedImagedSource) Envs(ctx context.Context, spec *api.ImageSpec
 	if err != nil {
 		return nil, err
 	}
+	if lsrc == nil {
+		return []EnvModifier{}, nil
+	}
 	return lsrc.Envs(ctx, spec)
 }
 
@@ -403,6 +406,9 @@ func (src *SpecMappedImagedSource) GetLayer(ctx context.Context, spec *api.Image
 	if err != nil {
 		return nil, err
 	}
+	if lsrc == nil {
+		return []AddonLayer{}, nil
+	}
 	return lsrc.GetLayer(ctx, spec)
 }
 
@@ -412,6 +418,9 @@ func (src *SpecMappedImagedSource) HasBlob(ctx context.Context, spec *api.ImageS
 	if err != nil {
 		return false
 	}
+	if lsrc == nil {
+		return false
+	}
 	return lsrc.HasBlob(ctx, spec, dgst)
 }
 
@@ -431,6 +440,9 @@ func (src *SpecMappedImagedSource) getDelegate(ctx context.Context, spec *api.Im
 	if err != nil {
 		return nil, err
 	}
+	if ref == "" {
+		return nil, nil
+	}
 
 	if s, ok := src.cache.Get(ref); ok {
 		return s.(LayerSource), nil

components/registry-facade/pkg/registry/registry.go

@@ -105,6 +105,15 @@ func NewRegistry(cfg config.Config, newResolver ResolverProvider, reg prometheus
 	}
 	layerSources = append(layerSources, ideLayerSource)
 
+	desktopIdeRefSource := func(s *api.ImageSpec) (ref string, err error) {
+		return s.DesktopIdeRef, nil
+	}
+	desktopIdeLayerSource, err := NewSpecMappedImageSource(newResolver, desktopIdeRefSource)
+	if err != nil {
+		return nil, err
+	}
+	layerSources = append(layerSources, desktopIdeLayerSource)
+
 	log.Info("preparing static layer")
 	staticLayer := NewRevisioningLayerSource(CompositeLayerSource{})
 	layerSources = append(layerSources, staticLayer)