Extend Blueprints to permit baseImageURI to be optionally overridden …

…for each Homeserver (#436)

* Refactor method to permit baseImageURI to be passed in for each Homeserver.

* Propigate error when images are unable to be constructed.

This provides better messages when using homerunner API to generate new
blueprints, otherwise the API only reports that no images exist.

internal/b/blueprints.go

@@ -54,6 +54,8 @@ type Homeserver struct {
 	Rooms []Room
 	// The list of application services to create on the homeserver
 	ApplicationServices []ApplicationService
+	// Optionally override the baseImageURI for blueprint creation
+	BaseImageURI *string
 }
 
 type User struct {

internal/docker/builder.go

@@ -181,7 +181,10 @@ func (d *Builder) ConstructBlueprintIfNotExist(bprint b.Blueprint) error {
 		return fmt.Errorf("ConstructBlueprintIfNotExist(%s): failed to ImageList: %w", bprint.Name, err)
 	}
 	if len(images) == 0 {
-		d.ConstructBlueprint(bprint)
+		err = d.ConstructBlueprint(bprint)
+		if err != nil {
+			return fmt.Errorf("ConstructBlueprintIfNotExist(%s): failed to ConstructBlueprint: %w", bprint.Name, err)
+		}
 	}
 	return nil
 }
@@ -380,9 +383,15 @@ func (d *Builder) constructHomeserver(blueprintName string, runner *instruction.
 // deployBaseImage runs the base image and returns the baseURL, containerID or an error.
 func (d *Builder) deployBaseImage(blueprintName string, hs b.Homeserver, contextStr, networkID string) (*HomeserverDeployment, error) {
 	asIDToRegistrationMap := asIDToRegistrationFromLabels(labelsForApplicationServices(hs))
+	var baseImageURI string
+	if hs.BaseImageURI == nil {
+		baseImageURI = d.Config.BaseImageURI
+	} else {
+		baseImageURI = *hs.BaseImageURI
+	}
 
 	return deployImage(
-		d.Docker, d.Config.BaseImageURI, fmt.Sprintf("complement_%s", contextStr),
+		d.Docker, baseImageURI, fmt.Sprintf("complement_%s", contextStr),
 		d.Config.PackageNamespace, blueprintName, hs.Name, asIDToRegistrationMap, contextStr,
 		networkID, d.Config,
 	)