Only one instance of mailer script can run at once

1 files changed, 20 insertions, 3 deletions

diff --git a/reports_mailer.py b/reports_mailer.py
index efac0de..19edbb9 100755
--- a/reports_mailer.py
+++ b/reports_mailer.py
@@ -19,6 +19,7 @@ import os
 import sys
 import json
 import time
+import fcntl
 import smtplib
 import logging
 import zipfile
@@ -91,7 +92,6 @@ def compress_directory(report_path, report_name):
     temp_file.seek(0)
     return temp_file.read()
 
-
 def prepare_message(subject, body, report_path, report_name):
     message = MIMEMultipart()
     message['Subject'] = subject
@@ -207,10 +207,27 @@ def load_configuration(config):
     SMTP_SERVER = config.get('mailer', 'smtp_server')
     SMTP_PORT = config.get('mailer', 'smtp_port')
 
+def already_running(lockfile):
+    descriptor = os.open(lockfile, os.O_CREAT|os.O_TRUNC|os.O_WRONLY)
+
+    try:
+        fcntl.lockf(descriptor, fcntl.LOCK_EX|fcntl.LOCK_NB)
+    except IOError:
+        return True
+
+    return False
+
 def main():
-    config = ConfigParser()
     script_path = os.path.abspath(__file__)
-    config_path = os.path.join(os.path.dirname(script_path), 'config.ini')
+    script_directory_path = os.path.dirname(script_path)
+
+    lockfile = os.path.join(script_directory_path, '.lock')
+    if already_running(lockfile):
+        print 'Can\'t run script, because it is already running.'
+        sys.exit(-1)
+
+    config = ConfigParser()
+    config_path = os.path.join(script_directory_path, 'config.ini')
 
     if len(config.read(config_path)) == 0:
         print 'Can\'t load configuration file.'