Add a hook for normalizing error messages and one for displaying proper status

amonit/hooks.py

@@ -30,13 +30,25 @@ def populate(context, args, key, table, replace=True):
     return (context, args)
 
 
-def recurrence(context, result, fields=["up"], dest="stable", dest_prev=None):
+def normalize(context, result, success="message", error="message", up="up"):
+    """ This hook is quasi-mandatory, as it normalizes the result to a dictionary
+    for further use.
+    """
+    if isinstance(result, Exception):
+        result = {up: False, error: str(result)}
+    elif not type(result) is dict:
+        result = {up: True, message: result}
+    return context, result
+
+
+def recurrence(context, result, fields={"up"}, dest="stable", dest_prev=None):
     """ Compute the recurrence of a the value of given fields
     """
     recur = {}
     prev = {}
+    fields = set(fields)
     if dest in context:
-        fields = fields + list(context[dest])
+        fields |= set(context[dest])
         if type(context[dest]) is dict:
             recur.update(context[dest])
     for field in fields:
@@ -46,9 +58,23 @@ def recurrence(context, result, fields=["up"], dest="stable", dest_prev=None):
             else 0
         )
         prev[field] = context.get(field, None)
-    context[dest] = recur
-    if prev is not None:
-        context[dest_prev] = prev
+    result[dest] = recur
+    if dest_prev is not None:
+        result[dest_prev] = prev
+    return context, result
+
+
+def status(context, result, up, down, recur="stable", field="up", dest="status"):
+    """ Converts the recurrence of the given field to a status based on thresholds
+    The simplest example will set the status to 'up' or 'down', more complex examples
+    might detect flapping or transient states.
+    """
+    recurrence = result.get(recur, {}).get(field, 0)
+    scale = up if result.get(field, False) else down
+    for level in reversed(sorted(scale.keys())):
+        if recurrence >= level:
+            result[dest] = scale[level]
+            break
     return context, result