Plugins skeleton, abstract class, public URL mounting

app/boot.py

@@ -9,6 +9,7 @@ from guardian.shortcuts import assign_perm
 
 from app.models import Preset
 from app.models import Theme
+from app.plugins import register_plugins
 from nodeodm.models import ProcessingNode
 # noinspection PyUnresolvedReferences
 from webodm.settings import MEDIA_ROOT
@@ -87,6 +88,9 @@ def boot():
         # Unlock any Task that might have been locked
         Task.objects.filter(processing_lock=True).update(processing_lock=False)
 
+        # Register plugins
+        register_plugins()
+
         if not settings.TESTING:
             # Setup and start scheduler
             scheduler.setup()

app/plugins/__init__.py

@@ -0,0 +1,2 @@
+from .plugin_base import PluginBase
+from .functions import *

app/plugins/functions.py

@@ -0,0 +1,65 @@
+import os
+import logging
+import importlib
+
+import django
+from django.conf.urls import url
+
+logger = logging.getLogger('app.logger')
+
+def register_plugins():
+    for plugin in get_active_plugins():
+        plugin.register()
+        logger.info("Registered {}".format(plugin))
+
+
+def get_url_patterns():
+    """
+    @return the patterns to expose the /public directory of each plugin (if needed)
+    """
+    url_patterns = []
+    for plugin in get_active_plugins():
+        if plugin.has_public_path():
+            url_patterns.append(url('^plugins/{}/(.*)'.format(plugin.get_name()),
+                                    django.views.static.serve,
+                                    {'document_root': plugin.get_path("public")}))
+    return url_patterns
+
+plugins = None
+def get_active_plugins():
+    # Cache plugins search
+    global plugins
+    if plugins != None: return plugins
+
+    plugins = []
+    plugins_path = get_plugins_path()
+
+    for dir in [d for d in os.listdir(plugins_path) if os.path.isdir(plugins_path)]:
+        # Each plugin must have a manifest.json and a plugin.py
+        plugin_path = os.path.join(plugins_path, dir)
+        manifest_path = os.path.join(plugin_path, "manifest.json")
+        pluginpy_path = os.path.join(plugin_path, "plugin.py")
+        disabled_path = os.path.join(plugin_path, "disabled")
+
+        if not os.path.isfile(manifest_path) or not os.path.isfile(pluginpy_path):
+            logger.warning("Found invalid plugin in {}".format(plugin_path))
+            continue
+
+        # Plugins that have a "disabled" file are disabled
+        if os.path.isfile(disabled_path):
+            continue
+
+        # Instantiate the plugin
+        try:
+            module = importlib.import_module("plugins.{}".format(dir))
+            cls = getattr(module, "Plugin")
+            plugins.append(cls())
+        except Exception as e:
+            logger.warning("Failed to instantiate plugin {}: {}".format(dir, e))
+
+    return plugins
+
+
+def get_plugins_path():
+    current_path = os.path.dirname(os.path.realpath(__file__))
+    return os.path.abspath(os.path.join(current_path, "..", "..", "plugins"))

app/plugins/plugin_base.py

@@ -0,0 +1,31 @@
+import logging, os, sys
+from abc import ABC, abstractmethod
+
+logger = logging.getLogger('app.logger')
+
+class PluginBase(ABC):
+    def __init__(self):
+        self.name = self.get_module_name().split(".")[-2]
+
+    @abstractmethod
+    def register(self):
+        pass
+
+    def get_path(self, *paths):
+        """
+        Gets the path of the directory of the plugin, optionally chained with paths
+        :return: path
+        """
+        return os.path.join(os.path.dirname(sys.modules[self.get_module_name()].__file__), *paths)
+
+    def get_name(self):
+        return self.name
+
+    def get_module_name(self):
+        return self.__class__.__module__
+
+    def has_public_path(self):
+        return os.path.isdir(self.get_path("public"))
+
+    def __str__(self):
+        return "[{}]".format(self.get_module_name())

app/urls.py

@@ -1,6 +1,7 @@
 from django.conf.urls import url, include
 
 from .views import app as app_views, public as public_views
+from .plugins import get_url_patterns
 
 from app.boot import boot
 from webodm import settings
@@ -24,6 +25,10 @@ urlpatterns = [
     url(r'^api/', include("app.api.urls")),
 ]
 
+# TODO: is there a way to place plugins /public directories
+# into the static build directories and let nginx serve them?
+urlpatterns += get_url_patterns()
+
 # Test cases call boot() independently
 if not settings.TESTING:
     boot()

plugins/volume/__init__.py

@@ -0,0 +1 @@
+from .plugin import *

plugins/volume/manifest.json

@@ -0,0 +1,13 @@
+{
+	"name": "Volume Measurements",
+	"webodmMinVersion": "0.4.2",
+	"description": "A plugin to compute volume measurements from a DSM",
+	"version": "0.1.0",
+	"author": "Piero Toffanin",
+	"email": "pt@masseranolabs.com",
+	"repository": "https://github.com/OpenDroneMap/WebODM",
+	"tags": ["volume", "measurements"],
+	"homepage": "https://github.com/OpenDroneMap/WebODM",
+	"experimental": true,
+	"deprecated": false
+}

plugins/volume/plugin.py

@@ -0,0 +1,6 @@
+from app.plugins import PluginBase
+
+class Plugin(PluginBase):
+
+    def register(self):
+        print("I'm registering!!!")

plugins/volume/public/hello.js

@@ -0,0 +1 @@
+console.log("HI!!");