fix firmware versioned attribute compatibility (#111)

The firmware payload written by the older style APIs was inconsistent
with the way that the setInventory and getInventory APIs were reading
it. This change provides an internal adapter structure to make sure the
data formats are consistent.

internal/inventory/component_attributes.go

@@ -29,11 +29,21 @@ func componentAttributesFromJSON(byt []byte) (*rivets.ComponentAttributes, error
 	return ca, nil
 }
 
+// for historical reasons, alloy used to store firmware data like this using a different API
+// we create this here to maintain compatibility with old data
+type firmwareContainer struct {
+	Firmware *common.Firmware `json:"firmware,omitempty"`
+}
+
 func mustFirmwareJSON(fw *common.Firmware) []byte {
 	if fw == nil {
 		return nil
 	}
-	byt, err := json.Marshal(fw)
+
+	fwc := &firmwareContainer{
+		Firmware: fw,
+	}
+	byt, err := json.Marshal(fwc)
 	if err != nil {
 		panic("bad firmware payload")
 	}
@@ -44,12 +54,12 @@ func firmwareFromJSON(byt []byte) (*common.Firmware, error) {
 	if byt == nil {
 		return nil, nil
 	}
-	fw := &common.Firmware{}
-	err := json.Unmarshal(byt, fw)
+	fwc := &firmwareContainer{}
+	err := json.Unmarshal(byt, fwc)
 	if err != nil {
 		return nil, err
 	}
-	return fw, nil
+	return fwc.Firmware, nil
 }
 
 type statusContainer struct {