From 9d98c523db3ac35e1e0f2bc94d0ec390858ae4f1 Mon Sep 17 00:00:00 2001
From: Cody Hiar <codyfh@gmail.com>
Date: Tue, 14 Feb 2017 09:06:37 -0700
Subject: Updates

---
 build/Dockerfile   |  8 +++---
 daemon_example.py  | 84 ++++++++++++++++++++++++++++++++++++++++++------------
 long_task.py       |  6 ++++
 unix_doublefork.py |  8 ------
 4 files changed, 75 insertions(+), 31 deletions(-)
 create mode 100644 long_task.py

diff --git a/build/Dockerfile b/build/Dockerfile
index f9e25a8..a23b6da 100644
--- a/build/Dockerfile
+++ b/build/Dockerfile
@@ -7,11 +7,11 @@ ENV TERM xterm-256color
 # Update and install
 RUN apt-get update && apt-get install -y \
       htop \
-      python-dev \
-      python-pip
+      python3-dev \
+      python3-pip
 
-# Add the project requirements
-ADD requirements.txt /opt/requirements.txt
+# # Add the project requirements
+# ADD requirements.txt /opt/requirements.txt
 
 # The code should be symlinked to this directory
 WORKDIR /app
diff --git a/daemon_example.py b/daemon_example.py
index 0eb3a7f..1ab9376 100755
--- a/daemon_example.py
+++ b/daemon_example.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 # -*- coding: utf-8 -*-
 """Example on how to create a daemon.
 
@@ -7,9 +7,11 @@ from the tests.
 
 https://pagure.io/python-daemon/blob/master/f/test/test_runner.py
 """
+import os
+import sys
 from logging import FileHandler, Formatter, getLogger, info
-from os import fork, setsid, getpid
-from sys import exit
+from os.path import isfile
+from signal import SIGINT, SIGTERM, signal
 from time import sleep
 
 
@@ -18,46 +20,90 @@ class MyDaemon(object):
 
     def __init__(self):
         """Initialize the paths and the pidfile of the daemon."""
-        self.stdin_path = '/dev/null'
-        self.stdout_path = '/dev/null'
-        self.stderr_path = '/dev/null'
+        # Setup logging
+        log = getLogger()
+        handler = FileHandler('/var/log/python_daemon.log')
+        formatter = Formatter('%(asctime)s %(levelname)s %(message)s')
+        handler.setFormatter(formatter)
+        log.addHandler(handler)
+        log.setLevel('INFO')
         self.pidfile_path = '/var/run/python_daemon.pid'
+        # Register handlers to exit when we get a kill signal
+        signal(SIGINT, self.exit_gracefully)
+        signal(SIGTERM, self.exit_gracefully)
+
+    def exit_gracefully(self, signum, frame):
+        """Exit Gracefully."""
+        info('I died')
+        self.remove_pidfile()
+        exit()
 
     def create_pidfile(self):
+        """Create a pidfile for the daemon."""
+        info('Creating pid file')
         with open(self.pidfile_path, mode='w', encoding='utf-8') as a_file:
             a_file.write(str('{}\n'.format(self.pid)))
 
+    def remove_pidfile(self):
+        """Remove the pidfile."""
+        info('Removing pidfile: {}'.format(self.pidfile_path))
+        os.remove(self.pidfile_path)
+
     def detach_process(self):
         """Simple method for daemonizing process."""
-        newpid = fork()
+        newpid = os.fork()
         if newpid > 0:
             exit()
         else:
-            setsid()
-            newpid = fork()
+            os.setsid()
+            newpid = os.fork()
             if newpid > 0:
                 exit()
             else:
-                self.pid = getpid()
-                self.create_pidfile()
+                self.pid = os.getpid()
                 return
 
     def run(self):
         """Entrypoint for the daemon."""
+        if isfile(self.pidfile_path):
+            print('Pidfile already exists, Daemon already running')
+            exit()
+        info('Starting up the python daemon.')
         self.detach_process()
-        # Setup logging
-        log = getLogger()
-        handler = FileHandler('/var/log/python_daemon.log')
-        formatter = Formatter('%(asctime)s %(levelname)s %(message)s')
-        handler.setFormatter(formatter)
-        log.addHandler(handler)
-        log.setLevel('INFO')
+        # redirect stdin, stdout and stderr to devnull
+        f = open(os.devnull, 'w')
+        sys.stdin = f
+        sys.stdout = f
+        sys.stderr = f
+        # Create the pid file
+        self.create_pidfile()
         while True:
             info('I am alive')
             sleep(1)
 
+    def stop(self):
+        """Stop a currently running process."""
+        try:
+            with open(self.pidfile_path, encoding='utf-8') as a_file:
+                pid = a_file.readline()
+                pid = pid.strip()  # Remove whitespace
+                os.kill(int(pid), SIGTERM)
+                exit()
+        except FileNotFoundError:
+            print('no pidfile found, is the daemon running?')
+            exit()
+
 
 # run the daemon
 if __name__ == '__main__':
     daemon = MyDaemon()
-    daemon.run()
+    if len(sys.argv) <= 1:
+        print('Usage: ./daemon_example.py \'start|stop\'')
+        exit()
+    if sys.argv[1] == 'start':
+        daemon.run()
+        exit()
+    if sys.argv[1] == 'stop':
+        daemon.stop()
+        exit()
+    print('Error: I dont know that command')
diff --git a/long_task.py b/long_task.py
new file mode 100644
index 0000000..eba74f8
--- /dev/null
+++ b/long_task.py
@@ -0,0 +1,6 @@
+# -*- coding: utf-8 -*-
+"""A long running task."""
+import time
+
+time.sleep(2)
+print('hi')
diff --git a/unix_doublefork.py b/unix_doublefork.py
index fc94a42..a98dfbf 100644
--- a/unix_doublefork.py
+++ b/unix_doublefork.py
@@ -27,11 +27,3 @@ else:
     else:
         print_process_info('Child')
         sys.exit()
-
-# # POP QUIZ!!!! Why won't this work
-# print_process_info('Parent')
-# os.setsid()
-# print_process_info('Parent')
-# newpid = os.fork()
-# if newpid == 0:
-#     print_process_info('Child')
-- 
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