determine ec2 instance id instead of node's dns name - it's safer to

reference

snseventd.py

@@ -184,7 +184,7 @@ args = parser.parse_args()
 ret = 1		# init as a failure code
 logFile = False
 Session = {}
-Session['nodename'] = str(os.uname().nodename.split('.')[0])
+Session['ec2id'] = "This is the actual EC2 instance name (i-blahblahblah)"
 
 Config = {}
 Config['debug'] = False
@@ -319,6 +319,17 @@ except Exception as e:
 	sys.exit(ret)
 
 
+# Get the EC2 session ID for this node
+printLog("Retrieving EC2 instance ID", loglevels.INFO)
+try:
+	Session['ec2'] = boto3.resource('ec2')
+	Session['ec2id'] = str(Session['ec2'].Instance('id'))
+except Exception as e:
+	printLog(e)
+	cleanup()
+	sys.exit(ret)
+printLog("This instance is "+Session['ec2id'], loglevels.DEBUG)
+
 # Retrieve the account number from the session so we can build arns
 printLog("Retrieving account info for generating ARNs", loglevels.INFO)
 try:
@@ -335,7 +346,7 @@ except Exception as e:
 
 
 # Create an SQS queue to subscribe to the SNS topic
-Session['queue'] = Config['sqsQueuePrefix']+Session['nodename']
+Session['queue'] = Config['sqsQueuePrefix'] + str(os.uname().nodename.split('.')[0])
 printLog("Creating SQS queue "+Session['queue'], loglevels.INFO)
 try:
 	Session['sqs'] = Session['boto3'].client('sqs')
@@ -440,16 +451,14 @@ while True:
 				raise Exception("Invalid JSON in message body")
 
 
-
-			# TODO: Add crypto signing support to verify message's origin
-
+# TODO: Add crypto signing support to verify message's origin
 
 
 			# Verify the message is sane
 			sanityCheckMessage(body, payload)
 
 			# Only proceed if the message is meant for either everyone or us explicitly
-			if '*' not in payload['nodes'] and Session['nodename'] not in payload['nodes']:
+			if '*' not in payload['nodes'] and Session['ec2id'] not in payload['nodes']:
 				printLog("Message not meant for us - ignoring it", loglevels.DEBUG)
 				continue