Merge pull request #175 from gregcorbett/issue-80

Remove python-daemon as a hard requirement

Author: tofu-rocketry

README.md

@@ -40,16 +40,17 @@ The Python STOMP library (N.B. versions between 3.1.1 (inclusive) and 5.0.0
 
 The Python AMS library. This is only required if you want to use AMS. See here for details on obtaining an RPM: https://github.com/ARGOeu/argo-ams-library/
 
-The Python daemon library
-* `yum install python-daemon`
-
 The Python ldap library
 * `yum install python-ldap`
 
 Optionally, the Python dirq library (N.B. this is only required if your messages
 are stored in a dirq structure)
 * `yum install python-dirq`
 
+The Python daemon library (N.B. installing this library is only required when
+using the SSM as a receiver)
+* `yum install python-daemon`
+
 You need a certificate and key in PEM format accessible to the SSM.
 There are a number of ways to do this.  One is to make a copy of the
 hostcert and hostkey files, owned by the apel user (created later):

apel-ssm.spec

@@ -21,7 +21,7 @@ BuildArch:      noarch
 BuildRequires:  python-devel
 %endif
 
-Requires:       stomppy < 5.0.0, python-daemon, python-ldap, openssl
+Requires:       stomppy < 5.0.0, python-ldap, openssl
 Requires(pre):  shadow-utils
 
 %define ssmconf %_sysconfdir/apel

ssm/agents.py

@@ -18,7 +18,6 @@
 
 from __future__ import absolute_import, division, print_function, unicode_literals
 
-from daemon import DaemonContext
 import logging
 import ldap
 import os
@@ -30,6 +29,13 @@
 except ImportError:
     import configparser as ConfigParser
 
+try:
+    from daemon import DaemonContext
+except ImportError:
+    # A error is logged and the receiver exits later if DaemonContext is
+    # requested but not installed.
+    DaemonContext = None
+
 from stomp.exception import NotConnectedException
 try:
     from argo_ams_library import AmsConnectionException
@@ -259,6 +265,13 @@ def run_sender(protocol, brokers, project, token, cp, log):
 
 def run_receiver(protocol, brokers, project, token, cp, log, dn_file):
     """Run Ssm2 as a receiver daemon."""
+    if DaemonContext is None:
+        log.error("Receiving SSMs must use python-daemon, but the "
+                  "python-daemon module wasn't found.")
+        log.error("System will exit.")
+        log.info(LOG_BREAK)
+        sys.exit(1)
+
     log.info('The SSM will run as a daemon.')
 
     # We need to preserve the file descriptor for any log files.