feature: add daemon layer

rerwatcher/__main__.py

@@ -1,10 +1,34 @@
 #!/usr/bin/env python3
 # coding: utf-8
+import os
+import sys
+
 from loguru import logger
 
 from rerwatcher.app import RerWatcher
 
-logger.add("log/file_{time}.log", rotation="00:00", retention="2 days")
+log_success = f'{os.path.dirname(__file__)}/../log/rerwatcher.success.log'
+log_error = f'{os.path.dirname(__file__)}/../log/rerwatcher.error.log'
+
+logger.remove()
+
+logger.add(log_success, rotation='00:00', retention='2 days', level='DEBUG')
+logger.add(log_error, rotation='00:00', retention='2 days', level='ERROR')
+
+daemon = RerWatcher(
+    pidfile='/tmp/rerwatcher.pid',
+    stdout=log_success,
+    stderr=log_error
+)
+
+if len(sys.argv) != 2:
+    print(f"Usage: {sys.argv[0]} [start|stop].", file=sys.stderr)
+    raise SystemExit(1)
 
-rer_watcher = RerWatcher()
-rer_watcher.start()
+if 'start' == sys.argv[1]:
+    daemon.start()
+elif 'stop' == sys.argv[1]:
+    daemon.stop()
+else:
+    print(f"Unknown command {sys.argv[1]!r}.", file=sys.stderr)
+    raise SystemExit(1)

rerwatcher/app.py

@@ -4,14 +4,17 @@
 import yaml
 from loguru import logger
 
-from rerwatcher.formatter import TransilienApiFormatter
 from rerwatcher.api import TransilienApi
+from rerwatcher.daemon import Daemon
 from rerwatcher.display import DisplayDeviceFactory
+from rerwatcher.formatter import TransilienApiFormatter
 
 
-class RerWatcher:
-    def __init__(self):
-        logger.info("Building RERWatcher app...")
+class RerWatcher(Daemon):
+    def __init__(self, *args, **kwargs):
+        app_name = self.__class__.__name__
+        super(RerWatcher, self).__init__(app_name=app_name, *args, **kwargs)
+
         config = RerWatcher.load_config()
         matrix_display = DisplayDeviceFactory.build(config)
         transilien_api = TransilienApi(config)
@@ -23,7 +26,6 @@ def __init__(self):
             api=transilien_api,
             formatter=transilien_formatter
         )
-        logger.info("RERWatcher app built.")
 
     @staticmethod
     def load_config():
@@ -39,13 +41,9 @@ def load_config():
 
         return config
 
-    def start(self):
+    def run(self):
         logger.info("Starting RERWatcher app...")
-        try:
-            self._app.start()
-        except KeyboardInterrupt:
-            logger.info("RERWatcher app stopped.")
-            pass
+        self._app.start()
 
 
 class _App:

rerwatcher/daemon.py

@@ -0,0 +1,80 @@
+import atexit
+import os
+import signal
+import sys
+from abc import ABC, abstractmethod
+
+
+class Daemon(ABC):
+    def __init__(self,
+                 pidfile: str,
+                 app_name: str,
+                 stdin: str = '/dev/null',
+                 stdout: str = '/dev/null',
+                 stderr: str = '/dev/null'
+                 ):
+        self.pidfile = pidfile
+        self.app_name = app_name
+        self.stdin = stdin
+        self.stdout = stdout
+        self.stderr = stderr
+
+    def daemonize(self):
+        if self._is_running():
+            raise RuntimeError(f"{self.app_name} is already Running.")
+
+        try:
+            if os.fork() > 0:
+                raise SystemExit(0)
+        except OSError:
+            raise RuntimeError("Fork #1 failed.")
+
+        os.chdir('/')
+        os.umask(0)
+        os.setsid()
+
+        try:
+            if os.fork() > 0:
+                raise SystemExit(0)
+        except OSError:
+            raise RuntimeError("Fork #2 failed.")
+
+        sys.stdout.flush()
+        sys.stderr.flush()
+
+        with open(self.stdin, 'rb') as f:
+            os.dup2(f.fileno(), sys.stdin.fileno())
+        with open(self.stdout, 'ab') as f:
+            os.dup2(f.fileno(), sys.stdout.fileno())
+        with open(self.stderr, 'ab') as f:
+            os.dup2(f.fileno(), sys.stderr.fileno())
+
+        with open(self.pidfile, 'w') as f:
+            print(os.getpid(), file=f)
+
+        atexit.register(lambda: os.remove(self.pidfile))
+
+        def sigterm_handler(signo, frame):
+            raise SystemExit(1)
+
+        signal.signal(signal.SIGTERM, sigterm_handler)
+
+    def _is_running(self):
+        return os.path.exists(self.pidfile)
+
+    def start(self):
+        self.daemonize()
+        self.run()
+
+    def stop(self):
+        if not self._is_running():
+            print(f"{self.app_name} is not running.")
+            raise SystemExit(1)
+
+        with open(self.pidfile) as f:
+            pid = int(f.read())
+            os.kill(pid, signal.SIGTERM)
+
+    @abstractmethod
+    def run(self):
+        raise NotImplementedError

tests/test_app.py

@@ -4,6 +4,8 @@
 import os
 from unittest.mock import patch, sentinel, call
 
+import pytest
+
 from rerwatcher.app import RerWatcher
 from tests.conftest import FAKE_CONFIG
 
@@ -35,8 +37,9 @@ def test_rerwatcher_workflow(mocker, mock_config):
         return_value=[sentinel.timetable1, sentinel.timetable2]
     )
 
-    app = RerWatcher()
-    app.start()
+    app = RerWatcher(None)
+    with pytest.raises(KeyboardInterrupt):
+        app._app.start()
 
     display_builder.assert_called_once_with(FAKE_CONFIG)
     api.assert_called_once_with(FAKE_CONFIG)