it works now. Plus comments

knockknock-daemon.py

@@ -23,7 +23,7 @@
 
 """
 
-import os, sys, pwd, grp, importlib
+import os, sys, pwd, grp
 from knockknock.LogFile import LogFile
 from knockknock.LogJournald import JournalReader
 from knockknock.Profiles import Profiles
@@ -47,13 +47,24 @@ def checkConfiguration():
         print "/etc/knockknock.d/profiles/ does not exist.  You need to setup your profiles first..."
         sys.exit(3)
 
+    # Retreive the system init type from /proc
     with open('/proc/1/status', 'r') as f:
         global initprocname
-        initprocname = f.readline().split[1]
-
-    if initprocname == "systemd" and importlib.util.find_spec("systemd") is None:
-        print "Your init system was detected as systemd but the python systemd module is not installed. You need to install it first..."
-        sys.exit(3)
+        initprocname = f.readline().split()[1]
+
+    # Verify whether or not the python-systemd dependency is required as well
+    # as whether or not it is fulfilled (optimistically written with python3
+    # support)
+    if (sys.version_info > (3, 0)):
+        import importlib
+        if initprocname == "systemd" and importlib.util.find_spec("systemd") is None:
+            print "Your init system was detected as systemd but the python systemd module is not installed. You need to install it first..."
+            sys.exit(3)
+    else:
+        import pkgutil
+        if initprocname == "systemd" and pkgutil.find_loader("systemd") is None:
+            print "Your init system was detected as systemd but the python systemd module is not installed. You need to install it first..."
+            sys.exit(3)
 
 def dropPrivileges():
     nobody = pwd.getpwnam('nobody')
@@ -69,12 +80,15 @@ def handleFirewall(input, config):
 
 def handleKnocks(output, profiles, config):
     dropPrivileges()
+    # Attempt to determine logging source here (since it shouldn't require
+    # elevated privileges to verify this information) based on the system
+    # init process
     if initprocname == "systemd":
         logSource      = JournalReader()
     elif initprocname in ["init", "preinit"]:
         logSource      = LogFile('/var/log/kern.log')
     else:
-        print "Failed to find logging source. Exiting"
+        print "Failed to find logging source for your init system. Exiting"
         sys.exit(3)
     portOpener   = PortOpener(output, config.getDelay())
     knockWatcher = KnockWatcher(config, logSource, profiles, portOpener)

knockknock/LogJournald.py

@@ -1,3 +1,9 @@
+"""
+Journald log reader event loop for knockknock-daemon.
+
+Contains the JournalReader class which takes no parameters and has 1 method:
+(tail)
+"""
 # Copyright (c) 2015 Jason Ritzke
 #
 # This program is free software; you can redistribute it and/or
@@ -17,18 +23,32 @@
 #
 
 import select
+import time
 from systemd import journal
 
-print(output)
 
 class JournalReader:
+    """
+    Journald reader for knockknock-daemon.
 
-    def tail(self):
-        j = journal.Reader()
-		j.seek_tail()
-		j.add_match('_TRANSPORT=kernel')
-		p = select.poll()
-		p.register(j, j.get_events())
+    Takes no parameters on initialization. Has a single event loop method
+    called tail that yields new messages in the kernel log.
+    """
 
-		p.poll()
-		yield j.get_next()['MESSAGE']
+    def __init__(self):
+        """Initalization method for JournalReader class."""
+        self.j = journal.Reader()
+        self.j.seek_tail()
+        self.j.add_match('_TRANSPORT=kernel')
+        self.p = select.poll()
+        self.p.register(self.j, self.j.get_events())
+
+    def tail(self):
+        """Generator that yields messages from the kernel log."""
+        while True:
+            self.p.poll()
+            line = self.j.get_next()
+            if 'MESSAGE' not in line:
+                time.sleep(.25)
+            else:
+                yield line['MESSAGE']