From 37c84020e98ae97356447740a0cf906bdb4d3e64 Mon Sep 17 00:00:00 2001
From: Ben Pfaff <blp@nicira.com>
Date: Fri, 16 Oct 2009 09:26:20 -0700
Subject: [PATCH] ovs-vsctl: Log changes to configuration file to syslog.

This feature, which has been in ovs-cfg-mod for some time as the "-c"
option, makes it much easier to see what changes ovs-vsctl actually makes
to ovs-vswitchd.conf.

CC: <Ian.Campbell@citrix.com>
---
 utilities/ovs-vsctl.8.in |  5 ++++
 utilities/ovs-vsctl.in   | 49 ++++++++++++++++++++++++++++++++++++++++
 2 files changed, 54 insertions(+)

diff --git a/utilities/ovs-vsctl.8.in b/utilities/ovs-vsctl.8.in
index b70f6c8d..acb4a80e 100644
--- a/utilities/ovs-vsctl.8.in
+++ b/utilities/ovs-vsctl.8.in
@@ -94,6 +94,11 @@ If neither \fB\-t\fR nor \fB\-\-target\fR is specified, the default target is
 Prevents \fBovs\-vsctl\fR from telling \fBovs\-vswitchd\fR to reload
 its configuration file.
 .
+.IP "\fB\-\-no\-syslog\fR"
+By default, \fBovs\-vsctl\fR logs its arguments and the details of any
+changes that it makes to the system log.  This option disables this
+logging.
+.
 .SH COMMANDS
 The commands implemented by \fBovs\-vsctl\fR are described in the
 sections below.
diff --git a/utilities/ovs-vsctl.in b/utilities/ovs-vsctl.in
index 675f9dd4..3bc9bc83 100755
--- a/utilities/ovs-vsctl.in
+++ b/utilities/ovs-vsctl.in
@@ -22,6 +22,7 @@ import re
 import socket
 import stat
 import sys
+import syslog
 
 argv0 = sys.argv[0]
 if argv0.find('/') >= 0:
@@ -35,11 +36,17 @@ VSWITCHD_TARGET = DEFAULT_VSWITCHD_TARGET
 
 RELOAD_VSWITCHD = True
 
+SYSLOG = True
+
 class Error(Exception):
     def __init__(self, msg):
         Exception.__init__(self)
         self.msg = msg
 
+def log(message):
+    if SYSLOG:
+        syslog.syslog(message)
+
 # XXX Most of the functions below should be integrated into a
 # VSwitchConfiguration object with logically named fields and methods
 # instead of this mishmash of functionality.
@@ -110,9 +117,42 @@ def cfg_read(filename, lock=False):
         if key not in cfg:
             cfg[key] = []
         cfg[key].append(value)
+
+    global orig_cfg
+    orig_cfg = cfg_clone(cfg)
+
     return cfg
 
+# Returns a deep copy of 'cfg', which must be in the format returned
+# by cfg_read().
+def cfg_clone(cfg):
+    new = {}
+    for key in cfg:
+        new[key] = list(cfg[key])
+    return new
+
+# Returns a list of all the configuration lines that are in 'a' but
+# not in 'b'.
+def cfg_subtract(a, b):
+    difference = []
+    for key in a:
+        for value in a[key]:
+            if key not in b or value not in b[key]:
+                difference.append("%s=%s" % (key, value))
+    return difference
+
 def do_cfg_save(cfg, file):
+    # Log changes.
+    added = cfg_subtract(cfg, orig_cfg)
+    removed = cfg_subtract(orig_cfg, cfg)
+    if added or removed:
+        log("configuration changes:")
+        for line in removed:
+            log("-%s\n" % line)
+        for line in added:
+            log("+%s\n" % line)
+
+    # Write changes.
     for key in sorted(cfg.keys()):
         for value in sorted(cfg[key]):
             file.write("%s=%s\n" % (key, value))
@@ -297,6 +337,7 @@ Interface commands (a bond consists of multiple interfaces):
 A bond is considered to consist of interfaces.
 
 General options:
+  --no-syslog                 do not write mesages to syslog
   -c, --config=FILE           set configuration file
                               (default: %(config)s)
   -t, --target=PIDFILE|SOCKET set ovs-vswitchd target
@@ -449,6 +490,7 @@ def main():
                                           ["config=",
                                            "target=",
                                            "no-reload",
+                                           "no-syslog",
                                            "help",
                                            "version"])
     except getopt.GetoptError, msg:
@@ -472,9 +514,16 @@ def main():
             usage()
         elif opt == "-V" or opt == "--version":
             version()
+        elif opt == "--no-syslog":
+            global SYSLOG
+            SYSLOG = False
         else:
             raise RuntimeError("unhandled option %s" % opt)
 
+    if SYSLOG:
+        syslog.openlog("ovs-vsctl")
+        log("Called as %s" % ' '.join(sys.argv[1:]))
+
     # Execute commands.
     if not args:
         sys.stderr.write("%s: missing command name (use --help for help)\n"
-- 
2.30.2