Merge pull request rsyslog#5271 from OrangeDog/patch-1

New fac-sever-rewrite.py for Python 3

plugins/external/messagemod/fac-sever-rewrite/fac-sever-rewrite.py

@@ -1,91 +1,120 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 
-"""A message modification plugin to rewrite message facility and severity.
+"""
+A message modification plugin to rewrite message facility and severity.
 
-   Note: this script must be customized according to your needs. It would
-         probably be a good idea to add command line options for the most
-	 common cases. Anyone up for that?
+Example usage:
 
-   Copyright (C) 2014 by Adiscon GmbH
+    module(load="mmexternal")
+    action(type="mmexternal"
+           binary="fac-sever-rewrite.py -s notice"
+           interface.input="fulljson")
 
-   This file is part of rsyslog.
+Note: this script should be customized according to your needs.
 
-   Licensed under the Apache License, Version 2.0 (the "License");
-   you may not use this file except in compliance with the License.
-   You may obtain a copy of the License at
+Copyright (c) 2014-2023 by Adiscon GmbH and James Howe
 
-         http://www.apache.org/licenses/LICENSE-2.0
-         -or-
-         see COPYING.ASL20 in the source distribution
+This file is part of rsyslog.
 
-   Unless required by applicable law or agreed to in writing, software
-   distributed under the License is distributed on an "AS IS" BASIS,
-   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-   See the License for the specific language governing permissions and
-   limitations under the License.
-"""
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
 
-import sys
-import re
-import json
+     http://www.apache.org/licenses/LICENSE-2.0
+     -or-
+     see COPYING.ASL20 in the source distribution
 
-# skeleton config parameters
-# currently none
-
-# App logic global variables
-
-def onInit():
-	""" Do everything that is needed to initialize processing (e.g.
-	    open files, create handles, connect to systems...)
-	"""
-
-
-def onReceive(msg):
-	"""This is the entry point where actual work needs to be done. It receives
-	   the messge from rsyslog and now needs to examine it, do any processing
-	   necessary. The to-be-modified properties (one or many) need to be pushed
-	   back to stdout, in JSON format, with no interim line breaks and a line
-	   break at the end of the JSON. If no field is to be modified, empty
-	   json ("{}") needs to be emitted.
-	   Note that no batching takes place (contrary to the output module skeleton)
-	   and so each message needs to be fully processed (rsyslog will wait for the
-	   reply before the next message is pushed to this module).
-	"""
-	#print msg
-	data = json.loads(msg)
-	newseverity = int(data["syslogseverity"]) + 1
-	print json.dumps({'syslogseverity': newseverity})
-
-def onExit():
-	""" Do everything that is needed to finish processing (e.g.
-	    close files, handles, disconnect from systems...). This is
-	    being called immediately before exiting.
-	"""
-	# most often, nothing to do here
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+"""
 
+import argparse
+import json
+import sys
+import syslog
+
+args = argparse.Namespace()
+
+
+def _facility(value) -> int:
+    try:
+        return int(value)
+    except ValueError:
+        name = 'LOG_' + value.upper()
+        const = getattr(syslog, name)
+        # Python's constants are for direct masking,
+        #   shift back to raw syslog value
+        return const >> 3
+
+
+def _severity(value) -> int:
+    try:
+        return int(value)
+    except ValueError:
+        name = 'LOG_' + value.upper()
+        const = getattr(syslog, name)
+        return const
+
+
+def on_init():
+    """
+    Do everything that is needed to initialize processing
+    (e.g. open files, create handles, connect to systems...)
+    """
+    parser = argparse.ArgumentParser(prog='fac-sever-rewrite.py')
+    parser.add_argument('-f', '--facility', required=False, type=_facility,
+                        help='Alias or integer of new facility to set')
+    parser.add_argument('-s', '--severity', required=False, type=_severity,
+                        help='Alias or integer of new severity to set')
+    parser.parse_args(namespace=args)
+
+
+def on_receive(msg: dict) -> dict:
+    """
+    This is the entry point where actual work needs to be done. It receives
+    the message from rsyslog and now needs to examine it, do any processing
+    necessary. The to-be-modified properties (one or many) need to be pushed
+    back to stdout, in JSON format, with no interim line breaks and a line
+    break at the end of the JSON. If no field is to be modified, empty
+    json ("{}") needs to be emitted.
+    Note that no batching takes place (contrary to the output module skeleton)
+    and so each message needs to be fully processed (rsyslog will wait for the
+    reply before the next message is pushed to this module).
+    """
+    changes = {}
+    if args.facility is not None:
+        changes['syslogfacility'] = args.facility
+    if args.severity is not None:
+        changes['syslogseverity'] = args.severity
+    return changes
+
+
+def on_exit():
+    """
+    Do everything that is needed to finish processing
+    (e.g. close files, handles, disconnect from systems...).
+    This is being called immediately before exiting.
+    """
+    pass
+
+
+def main():
+    """
+    -------------------------------------------------------
+    This is plumbing that DOES NOT need to be CHANGED
+    -------------------------------------------------------
+    """
+    on_init()
+    for line in sys.stdin:
+        msg = json.loads(line)
+        changes = on_receive(msg)
+        print(json.dumps(changes), flush=True)
+    on_exit()
+
+
+if __name__ == '__main__':
+    main()
 
-"""
--------------------------------------------------------
-This is plumbing that DOES NOT need to be CHANGED
--------------------------------------------------------
-Implementor's note: Python seems to very agressively
-buffer stdouot. The end result was that rsyslog does not
-receive the script's messages in a timely manner (sometimes
-even never, probably due to races). To prevent this, we
-flush stdout after we have done processing. This is especially
-important once we get to the point where the plugin does
-two-way conversations with rsyslog. Do NOT change this!
-See also: https://github.com/rsyslog/rsyslog/issues/22
-"""
-onInit()
-keepRunning = 1
-while keepRunning == 1:
-	msg = sys.stdin.readline()
-	if msg:
-		msg = msg[:-1] # remove LF
-		onReceive(msg)
-		sys.stdout.flush() # very important, Python buffers far too much!
-	else: # an empty line means stdin has been closed
-		keepRunning = 0
-onExit()
-sys.stdout.flush() # very important, Python buffers far too much!