Add example how to invoke "ssh" service from the command line

Author: amotl

README.rst

@@ -170,6 +170,9 @@ you an idea how to pass relevant information on the command line using JSON::
     # Launch "pushover" service plugin
     mqttwarn --plugin=pushover --options='{"title": "About", "message": "Hello world", "addrs": ["userkey", "token"], "priority": 6}'
 
+    # Launch "ssh" service plugin from the command line
+    mqttwarn --plugin=ssh --config='{"host": "ssh.example.org", "port": 22, "user": "foo", "password": "bar"}' --options='{"addrs": ["command with substitution %s"], "payload": "{\"args\": \"192.168.0.1\"}"}'
+
     # Launch "cloudflare_zone" service plugin from "mqttwarn-contrib", passing "--config" parameters via command line
     mqttwarn --plugin=mqttwarn_contrib.services.cloudflare_zone --config='{"auth-email": "foo", "auth-key": "bar"}' --options='{"addrs": ["0815", "www.example.org", ""], "message": "192.168.0.1"}'
 

mqttwarn/configuration.py

@@ -124,7 +124,7 @@ def level2number(self, level):
     def g(self, section, key, default=None):
         try:
             val = self.get(section, key)
-            if val.upper() in self.specials:
+            if isinstance(val, str) and val.upper() in self.specials:
                 return self.specials[val.upper()]
             return ast.literal_eval(val)
         except NoOptionError:

mqttwarn/services/ssh.py

@@ -68,7 +68,7 @@ def plugin(srv, item):
         _, stdout, stderr = ssh.exec_command(command)
 
     except Exception as e:
-        srv.logging.warning("Cannot run command %s on host %s" % (command, host))
+        srv.logging.warning("Cannot run command '%s' on host '%s'" % (command, host))
         srv.logging.warning("%s" % e)
         return False