rough plugin system implementation

fdroidserver/__main__.py

@@ -1,6 +1,7 @@
 #!/usr/bin/env python3
 #
 # fdroidserver/__main__.py - part of the FDroid server tools
+# Copyright (C) 2020 Michael Pöhn <michael.poehn@fsfe.org>
 # Copyright (C) 2010-2015, Ciaran Gultnieks, ciaran@ciarang.com
 # Copyright (C) 2013-2014 Daniel Marti <mvdan@mvdan.cc>
 #
@@ -20,7 +21,9 @@
 import sys
 import os
 import locale
+import pkgutil
 import logging
+import importlib
 
 import fdroidserver.common
 import fdroidserver.metadata
@@ -54,25 +57,49 @@ commands = OrderedDict([
 ])
 
 
-def print_help():
+def print_help(fdroid_modules=None):
     print(_("usage: ") + _("fdroid [<command>] [-h|--help|--version|<args>]"))
     print("")
     print(_("Valid commands are:"))
     for cmd, summary in commands.items():
         print("   " + cmd + ' ' * (15 - len(cmd)) + summary)
+    if fdroid_modules:
+        print(_('commands from plugin modules:'))
+        for command in sorted(fdroid_modules.keys()):
+            print('   {:15}{}'.format(command, fdroid_modules[command]['summary']))
     print("")
 
 
+def find_plugins():
+    fdroid_modules = [x[1] for x in pkgutil.iter_modules() if x[1].startswith('fdroid_')]
+    commands = {}
+    for module_name in fdroid_modules:
+        try:
+            command_name = module_name[7:]
+            module = importlib.import_module(module_name)
+            if hasattr(module, 'fdroid_summary') and hasattr(module, 'main'):
+                commands[command_name] = {'summary': module.fdroid_summary,
+                                          'module': module}
+        except IOError:
+            # We need to keep module lookup fault tolerant because buggy
+            # modules must not prevent fdroidserver from functioning
+            # TODO: think about warning users or debug logs for notifying devs
+            pass
+    return commands
+
+
 def main():
+    sys.path.append(os.getcwd())
+    fdroid_modules = find_plugins()
 
     if len(sys.argv) <= 1:
-        print_help()
+        print_help(fdroid_modules=fdroid_modules)
         sys.exit(0)
 
     command = sys.argv[1]
-    if command not in commands:
+    if command not in commands and command not in fdroid_modules.keys():
         if command in ('-h', '--help'):
-            print_help()
+            print_help(fdroid_modules=fdroid_modules)
             sys.exit(0)
         elif command == '--version':
             output = _('no version info found!')
@@ -103,7 +130,7 @@ def main():
             sys.exit(0)
         else:
             print(_("Command '%s' not recognised.\n" % command))
-            print_help()
+            print_help(fdroid_modules=fdroid_modules)
             sys.exit(1)
 
     verbose = any(s in sys.argv for s in ['-v', '--verbose'])
@@ -133,7 +160,10 @@ def main():
     sys.argv[0] += ' ' + command
 
     del sys.argv[1]
-    mod = __import__('fdroidserver.' + command, None, None, [command])
+    if command in commands.keys():
+        mod = __import__('fdroidserver.' + command, None, None, [command])
+    else:
+        mod = fdroid_modules[command]['module']
 
     system_langcode, system_encoding = locale.getdefaultlocale()
     if system_encoding is None or system_encoding.lower() not in ('utf-8', 'utf8'):

tests/main.TestCase

@@ -4,8 +4,11 @@ import inspect
 import optparse
 import os
 import sys
+import textwrap
 import unittest
+import tempfile
 from unittest import mock
+from testcommon import TmpCwd, TmpPyPath
 
 localmodule = os.path.realpath(
     os.path.join(os.path.dirname(inspect.getfile(inspect.currentframe())), '..'))
@@ -17,7 +20,7 @@ from fdroidserver import common
 import fdroidserver.__main__
 
 
-class FdroidTest(unittest.TestCase):
+class MainTest(unittest.TestCase):
     '''this tests fdroid.py'''
 
     def test_commands(self):
@@ -49,18 +52,43 @@ class FdroidTest(unittest.TestCase):
         co = mock.Mock()
         with mock.patch('sys.argv', ['', 'init', '-h']):
             with mock.patch('fdroidserver.init.main', co):
-                with mock.patch('sys.exit', lambda x: None):
+                with mock.patch('sys.exit') as exit_mock:
                     fdroidserver.__main__.main()
+                    exit_mock.assert_called_once_with(0)
         co.assert_called_once_with()
 
     def test_call_deploy(self):
         co = mock.Mock()
         with mock.patch('sys.argv', ['', 'deploy', '-h']):
             with mock.patch('fdroidserver.server.main', co):
-                with mock.patch('sys.exit', lambda x: None):
+                with mock.patch('sys.exit') as exit_mock:
                     fdroidserver.__main__.main()
+                    exit_mock.assert_called_once_with(0)
         co.assert_called_once_with()
 
+    def test_find_plugins(self):
+        with tempfile.TemporaryDirectory() as tmpdir, TmpCwd(tmpdir):
+            with open('fdroid_testy.py', 'w') as f:
+                f.write(textwrap.dedent("""\
+                        fdroid_summary = "ttt"
+                        main = lambda: 'all good'"""))
+            with TmpPyPath(tmpdir):
+                plugins = fdroidserver.__main__.find_plugins()
+            self.assertIn('testy', plugins.keys())
+            self.assertEqual(plugins['testy']['summary'], 'ttt')
+            self.assertEqual(plugins['testy']['module'].main(), 'all good')
+
+    def test_main_plugin(self):
+        with tempfile.TemporaryDirectory() as tmpdir, TmpCwd(tmpdir):
+            with open('fdroid_testy.py', 'w') as f:
+                f.write(textwrap.dedent("""\
+                        fdroid_summary = "ttt"
+                        main = lambda: pritn('all good')"""))
+            with mock.patch('sys.argv', ['', 'testy']):
+                with mock.patch('sys.exit') as exit_mock:
+                    fdroidserver.__main__.main()
+                    exit_mock.assert_called_once_with(0)
+
 
 if __name__ == "__main__":
     os.chdir(os.path.dirname(__file__))
@@ -71,5 +99,5 @@ if __name__ == "__main__":
     (common.options, args) = parser.parse_args(['--verbose'])
 
     newSuite = unittest.TestSuite()
-    newSuite.addTest(unittest.makeSuite(FdroidTest))
+    newSuite.addTest(unittest.makeSuite(MainTest))
     unittest.main(failfast=False)

tests/testcommon.py

@@ -16,6 +16,7 @@
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 import os
+import sys
 
 
 class TmpCwd():
@@ -32,3 +33,18 @@ class TmpCwd():
 
     def __exit__(self, a, b, c):
         os.chdir(self.orig_cwd)
+
+
+class TmpPyPath():
+    """Context-manager for temporarily changing the current working
+    directory.
+    """
+
+    def __init__(self, additional_path):
+        self.additional_path = additional_path
+
+    def __enter__(self):
+        sys.path.append(self.additional_path)
+
+    def __exit__(self, a, b, c):
+        sys.path.remove(self.additional_path)