Automatically install and update module dependencies

CHANGELOG.md

@@ -5,6 +5,10 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](http://keepachangelog.com/) 
 and this project adheres to [Semantic Versioning](http://semver.org/).
 
+## [Unreleased]
+### Added
+- Install dependencies automatically if the module provides a requirements.txt file
+
 ## [0.5] - 2017-03-22
 ### API changes
 - Remove Action.notify_message and Action.notify_error, which are synonyms for add_message and add_error

pext/__main__.py

@@ -29,6 +29,7 @@
 import getopt
 import json
 import os
+import pip
 import signal
 import sys
 import threading
@@ -426,6 +427,7 @@ def __init__(self, config_retriever: ConfigRetriever) -> None:
         """Initialize the module manager."""
         self.config_retriever = config_retriever
         self.module_dir = os.path.join(self.config_retriever.get_setting('config_path'), 'modules')
+        self.module_dependencies_dir = os.path.join(self.config_retriever.get_setting('config_path'), 'module_dependencies')
         self.logger = None  # type: Optional[Logger]
 
     @staticmethod
@@ -456,6 +458,15 @@ def _log_error(self, message: str) -> None:
         else:
             print(message)
 
+    def _pip_install(self, module_dir_name: str) -> None:
+        """Install module dependencies using pip."""
+        pip.main(['install',
+                  '--upgrade',
+                  '--target',
+                  os.path.join(self.module_dependencies_dir, module_dir_name),
+                  '-r',
+                  os.path.join(self.module_dir, module_dir_name, 'requirements.txt')])
+
     def bind_logger(self, logger: Logger) -> str:
         """Connect a logger to the module manager.
 
@@ -475,6 +486,11 @@ def load_module(self, window: 'Window', module: Dict) -> bool:
         module_dir = ModuleManager.add_prefix(module['name']).replace('.', '_')
         module_name = ModuleManager.remove_prefix(module['name'])
 
+        # Append module dependencies path if not yet appended
+        module_dependencies_path = os.path.join(self.config_retriever.get_setting('config_path'), 'module_dependencies', module_dir)
+        if module_dependencies_path not in sys.path:
+            sys.path.append(module_dependencies_path)
+
         # Prepare viewModel and context
         vm = ViewModel()
         module_context = QQmlContext(window.context)
@@ -492,6 +508,10 @@ def load_module(self, window: 'Window', module: Dict) -> bool:
         except ImportError as e1:
             self._log_error(
                 "Failed to load module {} from {}: {}".format(module_name, module_dir, e1))
+
+            # Remove module dependencies path
+            sys.path.remove(module_dependencies_path)
+
             return False
 
         Module = getattr(module_import, 'Module')
@@ -637,6 +657,11 @@ def install_module(self, url: str, verbose=False, interactive=True) -> bool:
 
             return False
 
+        if verbose:
+            self._log('Installing dependencies for {}'.format(module_name))
+
+        self._pip_install(dir_name)
+
         if verbose:
             self._log('Installed {}'.format(module_name))
 
@@ -659,6 +684,11 @@ def uninstall_module(self, module_name: str, verbose=False) -> bool:
 
             return False
 
+        try:
+            rmtree(os.path.join(self.module_dependencies_dir, dir_name))
+        except FileNotFoundError:
+            pass
+
         if verbose:
             self._log('Uninstalled {}'.format(module_name))
 
@@ -682,6 +712,11 @@ def update_module(self, module_name: str, verbose=False) -> bool:
 
             return False
 
+        if verbose:
+            self._log('Updating dependencies for {}'.format(module_name))
+
+        self._pip_install(dir_name)
+
         if verbose:
             self._log('Updated {}'.format(module_name))