feat: add the ability to load plugins in config

CONTRIBUTING.md

@@ -1,5 +1,4 @@
-Contributing
-============
+# Contributing
 
 All kinds of contributions to Dotbot are greatly appreciated. For someone
 unfamiliar with the code base, the most efficient way to contribute is usually
@@ -7,21 +6,19 @@ to submit a [feature request](#feature-requests) or [bug report](#bug-reports).
 If you want to dive into the source code, you can submit a [patch](#patches) as
 well, either working on your own ideas or [existing issues][issues].
 
-Feature Requests
-----------------
+## Feature Requests
 
 Do you have an idea for an awesome new feature for Dotbot? Please [submit a
 feature request][issue]. It's great to hear about new ideas.
 
 If you are inclined to do so, you're welcome to [fork][fork] Dotbot, work on
 implementing the feature yourself, and submit a patch. In this case, it's
-*highly recommended* that you first [open an issue][issue] describing your
+_highly recommended_ that you first [open an issue][issue] describing your
 enhancement to get early feedback on the new feature that you are implementing.
 This will help avoid wasted efforts and ensure that your work is incorporated
 into the code base.
 
-Bug Reports
------------
+## Bug Reports
 
 Did something go wrong with Dotbot? Sorry about that! Bug reports are greatly
 appreciated!
@@ -31,15 +28,14 @@ as Dotbot version, operating system, configuration file, error messages, and
 steps to reproduce the bug. The more details you can include, the easier it is
 to find and fix the bug.
 
-Patches
--------
+## Patches
 
 Want to hack on Dotbot? Awesome!
 
 If there are [open issues][issues], you're more than welcome to work on those -
 this is probably the best way to contribute to Dotbot. If you have your own
 ideas, that's great too! In that case, before working on substantial changes to
-the code base, it is *highly recommended* that you first [open an issue][issue]
+the code base, it is _highly recommended_ that you first [open an issue][issue]
 describing what you intend to work on.
 
 **Patches are generally submitted as pull requests.** Patches are also
@@ -50,6 +46,45 @@ used in the rest of the project. The version history should be clean, and
 commit messages should be descriptive and [properly
 formatted][commit-messages].
 
+When preparing a patch, it's recommended that you add unit tests
+that demonstrate the bug is fixed (or that the feature works).
+You can run the tests on your local machine by installing the `dev` extras.
+The steps below do this using a virtual environment:
+
+```shell
+# Create a local virtual environment
+$ python -m venv .venv
+
+# Activate the virtual environment
+# Cygwin, Linux, and MacOS:
+$ . .venv/bin/activate
+# Windows Powershell:
+$ & .venv\Scripts\Activate.ps1
+
+# Update pip and setuptools
+(.venv) $ python -m pip install -U pip setuptools
+
+# Install dotbot and its development dependencies
+(.venv) $ python -m pip install -e .[dev]
+
+# Run the unit tests
+(.venv) $ tox
+```
+
+If you prefer to run the tests in an isolated container using Docker, you can
+do so with the following:
+
+```
+docker run -it --rm -v "${PWD}:/dotbot" -w /dotbot python:3.10-alpine /bin/sh
+```
+
+If the machine you are running Docker on has SELinux in the enforcing state, you
+will have to disable that on the container. This can be done by adding
+`--security-opt label:disable` to the above command.
+
+After spawning the container, follow the same instructions as above (create a
+virtualenv, ..., run the tests).
+
 ---
 
 If you have any questions about anything, feel free to [ask][email]!

README.md

@@ -424,11 +424,26 @@ should do something and return whether or not it completed successfully.
 All built-in Dotbot directives are written as plugins that are loaded by
 default, so those can be used as a reference when writing custom plugins.
 
-Plugins are loaded using the `--plugin` and `--plugin-dir` options, using
-either absolute paths or paths relative to the base directory. It is
-recommended that these options are added directly to the `install` script.
+See [here](plugins) for a current list of plugins.
 
-See [here][plugins] for a current list of plugins.
+#### Format
+
+Plugins can be loaded either by the command-line arguments `--plugin` or
+`--plugin-dir` or by the `plugins` directive. Each of these take either
+absolute paths or paths relative to the base directory.
+
+When using command-line arguments to load multiple plugins you must add
+one argument for each plugin to be loaded. It is recommended to place
+these command-line arguments directly in the `install` script.
+
+The `plugins` config directive is specified as an array of paths to load.
+
+#### Example
+
+```yaml
+- plugins:
+    - dotbot-plugins/dotbot-template 
+```
 
 ## Command-line Arguments
 

dotbot/cli.py

@@ -84,7 +84,7 @@ def main():
 
         plugin_directories = list(options.plugin_dirs)
         if not options.disable_built_in_plugins:
-            from .plugins import Clean, Create, Link, Shell
+            from .plugins import Clean, Create, Link, Shell, Plugins
         plugin_paths = []
         for directory in plugin_directories:
           for plugin_path in glob.glob(os.path.join(directory, '*.py')):

dotbot/dispatcher.py

@@ -1,12 +1,21 @@
 import os
 from argparse import Namespace
+
+from .context import Context
 from .plugin import Plugin
 from .messenger import Messenger
-from .context import Context
+from .plugin import Plugin
+
 
 class Dispatcher(object):
-    def __init__(self, base_directory, only=None, skip=None, exit_on_failure=False,
-                 options=Namespace()):
+    def __init__(
+        self,
+        base_directory,
+        only=None,
+        skip=None,
+        exit_on_failure=False,
+        options=Namespace(),
+    ):
         self._log = Messenger()
         self._setup_context(base_directory, options)
         self._load_plugins()
@@ -15,55 +24,73 @@ class Dispatcher(object):
         self._exit = exit_on_failure
 
     def _setup_context(self, base_directory, options):
-        path = os.path.abspath(
-            os.path.expanduser(base_directory))
+        path = os.path.abspath(os.path.expanduser(base_directory))
         if not os.path.exists(path):
-            raise DispatchError('Nonexistent base directory')
+            raise DispatchError("Nonexistent base directory")
         self._context = Context(path, options)
 
     def dispatch(self, tasks):
         success = True
         for task in tasks:
             for action in task:
-                if (self._only is not None and action not in self._only \
-                        or self._skip is not None and action in self._skip) \
-                        and action != 'defaults':
-                    self._log.info('Skipping action %s' % action)
+                if (
+                    self._only is not None
+                    and action not in self._only
+                    or self._skip is not None
+                    and action in self._skip
+                ) and action != "defaults":
+                    self._log.info("Skipping action %s" % action)
                     continue
+
                 handled = False
-                if action == 'defaults':
-                    self._context.set_defaults(task[action]) # replace, not update
+                if action == "defaults":
+                    self._context.set_defaults(task[action])  # replace, not update
                     handled = True
                     # keep going, let other plugins handle this if they want
+
                 for plugin in self._plugins:
                     if plugin.can_handle(action):
                         try:
                             local_success = plugin.handle(action, task[action])
                             if not local_success and self._exit:
                                 # The action has failed exit
-                                self._log.error('Action %s failed' % action)
+                                self._log.error("Action %s failed" % action)
                                 return False
                             success &= local_success
                             handled = True
                         except Exception as err:
                             self._log.error(
-                                'An error was encountered while executing action %s' %
-                                action)
+                                "An error was encountered while executing action %s"
+                                % action
+                            )
                             self._log.debug(err)
                             if self._exit:
-                                # There was an execption exit
+                                # There was an exception exit
                                 return False
+
                 if not handled:
                     success = False
-                    self._log.error('Action %s not handled' % action)
+                    self._log.error("Action %s not handled" % action)
                     if self._exit:
                         # Invalid action exit
                         return False
+
+                if action == "plugins":
+                    # Create a list of loaded plugin names
+                    loaded_plugins = [
+                        plugin.__class__.__name__ for plugin in self._plugins
+                    ]
+
+                    # Load plugins that haven't been loaded yet
+                    for plugin in Plugin.__subclasses__():
+                        if plugin.__name__ not in loaded_plugins:
+                            self._plugins.append(plugin(self._context))
+
         return success
 
     def _load_plugins(self):
-        self._plugins = [plugin(self._context)
-            for plugin in Plugin.__subclasses__()]
+        self._plugins = [plugin(self._context) for plugin in Plugin.__subclasses__()]
+
 
 class DispatchError(Exception):
     pass

dotbot/plugins/__init__.py

@@ -1,4 +1,5 @@
 from .clean import Clean
 from .create import Create
 from .link import Link
+from .plugins import Plugins
 from .shell import Shell

dotbot/plugins/plugins.py

@@ -0,0 +1,46 @@
+import glob
+import os
+
+from ..plugin import Plugin
+from ..util import module
+
+
+class Plugins(Plugin):
+    """
+    Load plugins from a list of paths.
+    """
+
+    _directive = "plugins"
+    _has_shown_override_message = False
+
+    def can_handle(self, directive):
+        return directive == self._directive
+
+    def handle(self, directive, data):
+        if directive != self._directive:
+            raise ValueError("plugins cannot handle directive %s" % directive)
+        return self._process_plugins(data)
+
+    def _process_plugins(self, data):
+        success = True
+        plugin_paths = []
+        for item in data:
+            self._log.lowinfo("Loading plugin from %s" % item)
+
+            plugin_path_globs = glob.glob(os.path.join(item, "*.py"))
+            if not plugin_path_globs:
+                success = False
+                self._log.warning("Failed to load plugin from %s" % item)
+            else:
+                for plugin_path in plugin_path_globs:
+                    plugin_paths.append(plugin_path)
+
+        for plugin_path in plugin_paths:
+            abspath = os.path.abspath(plugin_path)
+            module.load(abspath)
+
+        if success:
+            self._log.info("All commands have been executed")
+        else:
+            self._log.error("Some commands were not successfully executed")
+        return success

dotbot/util/module.py

@@ -4,26 +4,26 @@ import sys, os.path
 loaded_modules = []
 
 def load(path):
-  basename = os.path.basename(path)
-  module_name, extension = os.path.splitext(basename)
-  plugin = load_module(module_name, path)
-  loaded_modules.append(plugin)
+    basename = os.path.basename(path)
+    module_name, extension = os.path.splitext(basename)
+    plugin = load_module(module_name, path)
+    loaded_modules.append(plugin)
 
 if sys.version_info >= (3, 5):
-  import importlib.util
+    import importlib.util
 
-  def load_module(module_name, path):
-    spec = importlib.util.spec_from_file_location(module_name, path)
-    module = importlib.util.module_from_spec(spec)
-    spec.loader.exec_module(module)
-    return module
+    def load_module(module_name, path):
+        spec = importlib.util.spec_from_file_location(module_name, path)
+        module = importlib.util.module_from_spec(spec)
+        spec.loader.exec_module(module)
+        return module
 elif sys.version_info >= (3, 3):
-  from importlib.machinery import SourceFileLoader
+    from importlib.machinery import SourceFileLoader
 
-  def load_module(module_name, path):
-    return SourceFileLoader(module_name, path).load_module()
+    def load_module(module_name, path):
+        return SourceFileLoader(module_name, path).load_module()
 else:
-  import imp
+    import imp
 
-  def load_module(module_name, path):
-    return imp.load_source(module_name, path)
+    def load_module(module_name, path):
+        return imp.load_source(module_name, path)

tests/dotbot_plugin_config_file.py

@@ -0,0 +1,19 @@
+"""Test that a plugin can be loaded by config file.
+
+This file is copied to a location with the name "config_file.py",
+and is then loaded from within the `test_cli.py` code.
+"""
+
+import os.path
+
+import dotbot
+
+
+class ConfigFile(dotbot.Plugin):
+    def can_handle(self, directive):
+        return directive == "plugin_config_file"
+
+    def handle(self, directive, data):
+        with open(os.path.abspath(os.path.expanduser("~/flag")), "w") as file:
+            file.write("config file plugin loading works")
+        return True