Added support for loading extensions

This patch adds support for loading extenions
to APRSD!!

You can create another separate aprsd project, and register
your extension in your setup.cfg as a new entry point for aprsd
like

[entry_points]
aprsd.extension =
    cool = my_project.extension

in your my_project/extension.py file
import your commmands and away you go.

aprsd/cli_helper.py

@@ -50,6 +50,43 @@ common_options = [
 ]
 
 
+import click
+
+
+class AliasedGroup(click.Group):
+    def command(self, *args, **kwargs):
+        """A shortcut decorator for declaring and attaching a command to
+        the group.  This takes the same arguments as :func:`command` but
+        immediately registers the created command with this instance by
+        calling into :meth:`add_command`.
+        Copied from `click` and extended for `aliases`.
+        """
+        def decorator(f):
+            aliases = kwargs.pop('aliases', [])
+            cmd = click.decorators.command(*args, **kwargs)(f)
+            self.add_command(cmd)
+            for alias in aliases:
+                self.add_command(cmd, name=alias)
+            return cmd
+        return decorator
+
+    def group(self, *args, **kwargs):
+        """A shortcut decorator for declaring and attaching a group to
+        the group.  This takes the same arguments as :func:`group` but
+        immediately registers the created command with this instance by
+        calling into :meth:`add_command`.
+        Copied from `click` and extended for `aliases`.
+        """
+        def decorator(f):
+            aliases = kwargs.pop('aliases', [])
+            cmd = click.decorators.group(*args, **kwargs)(f)
+            self.add_command(cmd)
+            for alias in aliases:
+                self.add_command(cmd, name=alias)
+            return cmd
+        return decorator
+
+
 def add_options(options):
     def _add_options(func):
         for option in reversed(options):

aprsd/main.py

@@ -59,20 +59,25 @@ click_completion.core.startswith = custom_startswith
 click_completion.init()
 
 
-@click.group(context_settings=CONTEXT_SETTINGS)
+@click.group(cls=cli_helper.AliasedGroup, context_settings=CONTEXT_SETTINGS)
 @click.version_option()
 @click.pass_context
 def cli(ctx):
     pass
 
 
-def main():
-    # First import all the possible commands for the CLI
-    # The commands themselves live in the cmds directory
+def load_commands():
     from .cmds import (  # noqa
         completion, dev, fetch_stats, healthcheck, list_plugins, listen,
         send_message, server, webchat,
     )
+
+
+def main():
+    # First import all the possible commands for the CLI
+    # The commands themselves live in the cmds directory
+    load_commands()
+    utils.load_entry_points("aprsd.extension")
     cli(auto_envvar_prefix="APRSD")
 
 

aprsd/utils/__init__.py

@@ -4,6 +4,7 @@ import errno
 import os
 import re
 import sys
+import traceback
 
 import update_checker
 
@@ -131,3 +132,21 @@ def parse_delta_str(s):
         return {key: float(val) for key, val in m.groupdict().items()}
     else:
         return {}
+
+
+def load_entry_points(group):
+    """Load all extensions registered to the given entry point group"""
+    print(f"Loading extensions for group {group}")
+    try:
+        import importlib_metadata
+    except ImportError:
+        # For python 3.10 and later
+        import importlib.metadata as importlib_metadata
+
+    eps = importlib_metadata.entry_points(group=group)
+    for ep in eps:
+        try:
+            ep.load()
+        except Exception as e:
+            print(f"Extension {ep.name} of group {group} failed to load with {e}", file=sys.stderr)
+            print(traceback.format_exc(), file=sys.stderr)