Make percentage_format_string support str.format() syntax

CHANGELOG.md

@@ -22,6 +22,7 @@
 - Apply percentage_format_string to match_body percentage value; will appear in new percentage_formatted key - [#387](https://github.com/jertel/elastalert2/pull/387) - @iamxeph
 - Add support for Kibana 7.14 for Kibana Discover - [#392](https://github.com/jertel/elastalert2/pull/392) - @nsano-rururu
 - Add metric_format_string optional configuration for Metric Aggregation to format aggregated value - [#399](https://github.com/jertel/elastalert2/pull/399) - @iamxeph
+- Make percentage_format_string support format() syntax in addition to old %-formatted syntax - [#403](https://github.com/jertel/elastalert2/pull/403) - @iamxeph
 
 ## Other changes
 - [Tests] Improve test code coverage - [#331](https://github.com/jertel/elastalert2/pull/331) - @nsano-rururu

docs/source/ruletypes.rst

@@ -1263,7 +1263,7 @@ allign with the time elastalert runs, (This both avoid calculations on partial d
 See: https://www.elastic.co/guide/en/elasticsearch/reference/current/search-aggregations-bucket-datehistogram-aggregation.html#_offset for a
 more comprehensive explaination.
 
-``metric_format_string``: An optional format string applies to the aggregated metric value in the alert match text and match_body. This adds 'metric_{metric_agg_key}_formatted' value to the match_body in addition to raw, unformatted 'metric_{metric_agg_key}' value so that you can use the values for ``alert_subject_args`` and ``alert_text_args``. Must be a valid python format string. Both format() and %-formatted syntax works. For example, "{:.2%}" will format '0.966666667' to '96.67%', and "%.2f" will format '0.966666667' to '0.97'.
+``metric_format_string``: An optional format string applies to the aggregated metric value in the alert match text and match_body. This adds 'metric_{metric_agg_key}_formatted' value to the match_body in addition to raw, unformatted 'metric_{metric_agg_key}' value so that you can use the values for ``alert_subject_args`` and ``alert_text_args``. Must be a valid python format string. Both str.format() and %-format syntax works. For example, "{:.2%}" will format '0.966666667' to '96.67%', and "%.2f" will format '0.966666667' to '0.97'.
 See: https://docs.python.org/3.4/library/string.html#format-specification-mini-language
 
 
@@ -1347,8 +1347,7 @@ evaluated separately against the threshold(s).
 
 ``sync_bucket_interval``: See ``sync_bucket_interval`` in  Metric Aggregation rule
 
-``percentage_format_string``: An optional format string to apply to the percentage value in the alert match text. This also adds 'percentage_formatted' value to the match_body in addition to raw, unformatted 'percentage' value so that you can use the formatted value for ``alert_subject_args`` and ``alert_text_args``. Must be a valid python format string.
-For example, "%.2f" will round it to 2 decimal places.
+``percentage_format_string``: An optional format string applies to the percentage value in the alert match text and match_body. This adds 'percentage_formatted' value to the match_body in addition to raw, unformatted 'percentage' value so that you can use the values for ``alert_subject_args`` and ``alert_text_args``. Must be a valid python format string. Both str.format() and %-format syntax works. For example, both "{:.2f}" and "%.2f" will format '96.6666667' to '96.67'.
 See: https://docs.python.org/3.4/library/string.html#format-specification-mini-language
 
 ``min_denominator``: Minimum number of documents on which percentage calculation will apply. Default is 0.

elastalert/ruletypes.py

@@ -7,7 +7,7 @@
 
 from elastalert.util import (add_raw_postfix, dt_to_ts, EAException, elastalert_logger, elasticsearch_client,
                              format_index, hashable, lookup_es_key, new_get_event_ts, pretty_ts, total_seconds,
-                             ts_now, ts_to_dt, expand_string_into_dict)
+                             ts_now, ts_to_dt, expand_string_into_dict, format_string)
 
 
 class RuleType(object):
@@ -1072,7 +1072,7 @@ def get_match_str(self, match):
         message = 'Threshold violation, %s:%s %s (min: %s max : %s) \n\n' % (
             self.rules['metric_agg_type'],
             self.rules['metric_agg_key'],
-            self.format_string(metric_format_string, match[self.metric_key]) if metric_format_string else match[self.metric_key],
+            format_string(metric_format_string, match[self.metric_key]) if metric_format_string else match[self.metric_key],
             self.rules.get('min_threshold'),
             self.rules.get('max_threshold')
         )
@@ -1098,7 +1098,7 @@ def check_matches(self, timestamp, query_key, aggregation_data):
                          self.metric_key: metric_val}
                 metric_format_string = self.rules.get('metric_format_string', None)
                 if metric_format_string is not None:
-                    match[self.metric_key +'_formatted'] = self.format_string(metric_format_string, metric_val)
+                    match[self.metric_key +'_formatted'] = format_string(metric_format_string, metric_val)
                 if query_key is not None:
                     match = expand_string_into_dict(match, self.rules['query_key'], query_key)
                 self.add_match(match)
@@ -1140,12 +1140,6 @@ def crossed_thresholds(self, metric_value):
             return True
         return False
 
-    def format_string(self, format_config, target_value):
-        if (format_config.startswith('{')):
-            return format_config.format(target_value)
-        else:
-            return format_config % (target_value)
-
 
 class SpikeMetricAggregationRule(BaseAggregationRule, SpikeRule):
     """ A rule that matches when there is a spike in an aggregated event compared to its reference point """
@@ -1258,7 +1252,7 @@ def __init__(self, *args):
     def get_match_str(self, match):
         percentage_format_string = self.rules.get('percentage_format_string', None)
         message = 'Percentage violation, value: %s (min: %s max : %s) of %s items\n\n' % (
-            percentage_format_string % (match['percentage']) if percentage_format_string else match['percentage'],
+            format_string(percentage_format_string, match['percentage']) if percentage_format_string else match['percentage'],
             self.rules.get('min_percentage'),
             self.rules.get('max_percentage'),
             match['denominator']
@@ -1297,7 +1291,7 @@ def check_matches(self, timestamp, query_key, aggregation_data):
                     match = {self.rules['timestamp_field']: timestamp, 'percentage': match_percentage, 'denominator': total_count}
                     percentage_format_string = self.rules.get('percentage_format_string', None)
                     if percentage_format_string is not None:
-                        match['percentage_formatted'] = percentage_format_string % (match_percentage)
+                        match['percentage_formatted'] = format_string(percentage_format_string, match_percentage)
                     if query_key is not None:
                         match = expand_string_into_dict(match, self.rules['query_key'], query_key)
                     self.add_match(match)
@@ -1307,4 +1301,4 @@ def percentage_violation(self, match_percentage):
             return True
         if 'min_percentage' in self.rules and match_percentage < self.rules['min_percentage']:
             return True
-        return False
+        return False

elastalert/util.py

@@ -518,3 +518,18 @@ def expand_string_into_dict(dictionary, string , value, sep='.'):
         field1, new_string = string.split(sep, 1)
         dictionary[field1] = _expand_string_into_dict(new_string, value)
     return dictionary
+
+
+def format_string(format_config, target_value):
+    """
+    Formats number, supporting %-format and str.format() syntax.
+
+    :param format_config: string format syntax, for example '{:.2%}' or '%.2f'
+    :param target_value: number to format
+    :rtype: string
+    """
+    if (format_config.startswith('{')):
+        return format_config.format(target_value)
+    else:
+        return format_config % (target_value)
+

tests/rules_test.py

@@ -1303,6 +1303,12 @@ def test_percentage_match():
     assert '76.1589403974' in rule.get_match_str(rule.matches[0])
     assert rule.matches[0]['percentage'] == 76.15894039742994
     assert 'percentage_formatted' not in rule.matches[0]
+    rules['percentage_format_string'] = '{:.2f}'
+    rule = PercentageMatchRule(rules)
+    rule.check_matches(datetime.datetime.now(), None, create_percentage_match_agg(76.666666667, 24))
+    assert '76.16' in rule.get_match_str(rule.matches[0])
+    assert rule.matches[0]['percentage'] == 76.15894039742994
+    assert rule.matches[0]['percentage_formatted'] == '76.16'
     rules['percentage_format_string'] = '%.2f'
     rule = PercentageMatchRule(rules)
     rule.check_matches(datetime.datetime.now(), None, create_percentage_match_agg(76.666666667, 24))

tests/util_test.py

@@ -35,6 +35,7 @@
 from elastalert.util import ts_utc_to_tz
 from elastalert.util import expand_string_into_dict
 from elastalert.util import unixms_to_dt
+from elastalert.util import format_string
 
 
 @pytest.mark.parametrize('spec, expected_delta', [
@@ -502,3 +503,11 @@ def test_dt_to_int():
     actual = dt_to_int(dt)
     expected = 1625529600000
     assert expected == actual
+
+
+def test_format_string():
+    target = 0.966666667
+    expected_percent_formatting = '0.97'
+    assert format_string('%.2f', target) == expected_percent_formatting
+    expected_str_formatting = '96.67%'
+    assert format_string('{:.2%}', target) == expected_str_formatting