Allow plugins to be loaded from an external directory

InvenTree/plugin/helpers.py

@@ -172,10 +172,16 @@ class GitStatus:
 
 
 # region plugin finders
-def get_modules(pkg):
+def get_modules(pkg, path=None):
     """Get all modules in a package."""
     context = {}
-    for loader, name, _ in pkgutil.walk_packages(pkg.__path__):
+
+    if path is None:
+        path = pkg.__path__
+    elif type(path) is not list:
+        path = [path]
+
+    for loader, name, _ in pkgutil.walk_packages(path):
         try:
             module = loader.find_module(name).load_module(name)
             pkg_names = getattr(module, '__all__', None)
@@ -199,7 +205,7 @@ def get_classes(module):
     return inspect.getmembers(module, inspect.isclass)
 
 
-def get_plugins(pkg, baseclass):
+def get_plugins(pkg, baseclass, path=None):
     """Return a list of all modules under a given package.
 
     - Modules must be a subclass of the provided 'baseclass'
@@ -207,7 +213,7 @@ def get_plugins(pkg, baseclass):
     """
     plugins = []
 
-    modules = get_modules(pkg)
+    modules = get_modules(pkg, path=path)
 
     # Iterate through each module in the package
     for mod in modules:

InvenTree/plugin/registry.py

@@ -197,7 +197,23 @@ class PluginsRegistry:
 
         # Collect plugins from paths
         for plugin in settings.PLUGIN_DIRS:
-            modules = get_plugins(importlib.import_module(plugin), InvenTreePlugin)
+
+            parent_path = None
+
+            # If a "path" is provided, some special handling is required
+            if os.path.sep in plugin:
+                path_split = [el for el in plugin.split(os.path.sep)]
+
+                if len(path_split) > 0:
+                    parent_path = os.path.sep.join(path_split[:-1])
+
+                    if not parent_path.endswith(os.path.sep):
+                        parent_path += os.path.sep
+
+                    plugin = path_split[-1]
+
+            modules = get_plugins(importlib.import_module(plugin), InvenTreePlugin, path=parent_path)
+
             if modules:
                 [self.plugin_modules.append(item) for item in modules]