--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mrtg.py	Sun Dec 06 02:25:15 2009 +0200
@@ -0,0 +1,116 @@
+"""
+    Definitions for MRTG
+"""
+
+class Target (object) :
+    """
+        A monitoring target
+    """
+
+    def __init__ (self, name, target_def, max_bytes, title, comment=None) :
+        """
+            Store values corresponding to the MRTG configuration statements:
+                name        - the unique identifier for this target
+                target_def  - the Target[] definition, see target_def()
+                max_bytes   - maximum number of bytes/s accepted for this interface, used to determine % load
+                title       - human-readable title
+                comment     - optional comment field
+        """
+
+        self.name = name
+        self.target_def = target_def
+        self.max_bytes = max_bytes
+        self.title = title
+        self.comment = comment
+
+    def statement (self, name, value) :
+        """
+            Yield the line for a single stanza:
+                Stanza[identifier]: value
+        """
+
+        return "%s[%s]: %s" % (name, self.name, value)
+
+    def generate (self) :
+        """
+            Return a series of lines for this target
+        """
+
+        if self.comment :
+            yield "# %s" % (self.comment, )
+
+        yield self.statement('Target', self.target_def)
+        yield self.statement('MaxBytes', self.max_bytes)
+        yield self.statement('Title', self.title)
+
+class Host (object) :
+    """
+        A SNMP target
+    """
+
+    def __init__ (self, name, hostname, snmp_community) :
+        """
+            Store values corresponding to the MRTG Target stanza bits:
+                name            - short name
+                hostname        - the snmp target
+                snmp_community  - the SNMP community to use
+        """
+
+        self.name = name
+        self.hostname = hostname
+        self.snmp_community = snmp_community
+
+    def port (self, port_name, mbps, port=None, descr=None, port_title=None) :
+        """
+            Create and return a Target describing the given port/interface on this host.
+        """
+        
+        # figure out which ifref to use
+        ifid = iftitle = None
+
+        for prefix, tprefix, value in (
+                ('',    "#",    port),
+                ('\\',  "",     descr),
+        ) :
+            if value :
+                # ok, use this
+                ifid = prefix + str(value)
+
+                if port_title :
+                    iftitle = port_title
+
+                else :
+                    iftitle = tprefix + str(value)
+
+                break
+        
+        if not ifid :
+            raise ValueError("No interface identifier given")
+        
+        # compose
+        name = "%s_%s" % (self.hostname, port_name)
+        target = "%s:%s@%s" % (ifid, self.snmp_community, self.hostname)
+        max_bytes = mbps * 1000 * 1000 / 8
+        title = "Traffic @ %s %s -> %s" % (self.name, iftitle, port_name)
+
+        # build and return Target
+        return Target(name, target, max_bytes, title)
+
+def write_cfg (path, targets) :
+    """
+        Write out the given targets to the given file
+    """
+
+    fh = open(path, 'w')
+    
+    # generate() each target
+    for target in targets :
+        for line in target.generate() :
+            # output line
+            fh.write(line + '\n')
+         
+        # separate by empty line
+        fh.write('\n')
+    
+    fh.close()
+