Gauge type override logic for blob series

Some vendors like Fortigate publish sensor values as OCTECTSTR
instead of doing like Cisco and scaling the value. This commit
will export metrics that can be fully (all values) converted to
float as a gauge series.

Author: bluecmd

src/snmpcollector/src/exporter.py

@@ -120,6 +120,14 @@ def export(self, target, result):
       target.host, target.layer, result.index, result.data.type)] = (
           result.data.value, target.timestamp, result.labels)
 
+  def is_only_numeric(self, labels_map):
+    for (value, _, _) in labels_map.itervalues():
+      try:
+        float(value)
+      except ValueError:
+        return False
+    return True
+
   def run_dump(self):
     while True:
       # Since the label map will be mutated we need to do a deep copy here.
@@ -131,6 +139,13 @@ def run_dump(self):
       # Assemble the output
       out = []
       for obj, (mib, metrics_type, labels_map) in metrics_copy.iteritems():
+        # Some vendors (e.g. Fortigate) choose to have decimal values as
+        # OCTETSTR instead of a scaled value. Try to convert all values, if
+        # we succeed export this metric as guage.
+        convert_to_float = False
+        if metrics_type == 'blob' and self.is_only_numeric(labels_map):
+          metrics_type = 'gauge'
+          convert_to_float = True
         if metrics_type != 'counter' and metrics_type != 'gauge':
           continue
         out.append('# HELP {0} {1}::{0}\n'.format(obj, mib))
@@ -150,6 +165,9 @@ def run_dump(self):
           label_string = ','.join(label_list)
           instance = ''.join([obj, '{', label_string, '}'])
 
+          if convert_to_float:
+            value = float(value)
+
           out.append('{0} {1} {2}\n'.format(
             instance, value, int(timestamp * 1000)))