Check bucket rules are being followed

Signed-off-by: Brian Brazil <brian.brazil@robustperception.io>

Author: brian-brazil

prometheus_client/core.py

@@ -66,6 +66,9 @@ def __float__(self):
     def __eq__(self, other):
         return type(self) == type(other) and self.sec == other.sec and self.nsec == other.nsec
 
+    def __ne__(self, other):
+        return not self == other
+
     def __gt__(self, other):
         return self.sec > other.sec or self.nsec > other.nsec
 

prometheus_client/openmetrics/parser.py

@@ -249,6 +249,42 @@ def _group_for_sample(sample, name, typ):
     return sample.labels
 
 
+def _check_histogram(samples, name):
+    group = None
+    timestamp = None
+
+    def do_checks():
+        if bucket != float('+Inf'):
+            raise ValueError("+Inf bucket missing: " + name)
+        if count is not None and value != count:
+            raise ValueError("Count does not match +Inf value: " + name)
+
+    for s in samples:
+        suffix = s.name[len(name):]
+        g = _group_for_sample(s, name, 'histogram')
+        if g != group or s.timestamp != timestamp:
+            if group is not None:
+                do_checks()
+            count = None
+            bucket = -1
+            value = 0
+        group = g
+        timestamp = s.timestamp
+
+        if suffix == '_bucket':
+            b = float(s.labels['le'])
+            if b <= bucket:
+                raise ValueError("Buckets out of order: " + name)
+            if s.value < value:
+                raise ValueError("Bucket values out of order: " + name)
+            bucket = b
+            value = s.value
+        elif suffix in ['_count', '_gcount']:
+            count = s.value
+    if group is not None:
+        do_checks()
+
+
 def text_fd_to_metric_families(fd):
     """Parse Prometheus text format from a file descriptor.
 
@@ -284,9 +320,10 @@ def build_metric(name, documentation, typ, unit, samples):
             raise ValueError("Unit does not match metric name: " + name)
         if unit and typ in ['info', 'stateset']:
             raise ValueError("Units not allowed for this metric type: " + name)
+        if typ in ['histogram', 'gaugehistogram']:
+            _check_histogram(samples, name)
         metric = core.Metric(name, documentation, typ, unit)
         # TODO: check labelvalues are valid utf8
-        # TODO: Check histogram bucket rules being followed
         # TODO: Check for duplicate samples
         metric.samples = samples
         return metric

tests/openmetrics/test_parser.py

@@ -528,6 +528,14 @@ def test_invalid_input(self):
                 ('# TYPE a gaugehistogram\na_bucket{le="+Inf"} NaN\n# EOF\n'),
                 ('# TYPE a summary\na_sum NaN\n# EOF\n'),
                 ('# TYPE a summary\na_count NaN\n# EOF\n'),
+                # Bad histograms.
+                ('# TYPE a histogram\na_sum 1\n# EOF\n'),
+                ('# TYPE a gaugehistogram\na_gsum 1\n# EOF\n'),
+                ('# TYPE a histogram\na_count 1\na_bucket{le="+Inf"} 0\n# EOF\n'),
+                ('# TYPE a histogram\na_bucket{le="+Inf"} 0\na_count 1\n# EOF\n'),
+                ('# TYPE a histogram\na_bucket{le="+Inf"} 0\na_bucket{le="+Inf"} 0\n# EOF\n'),
+                ('# TYPE a histogram\na_bucket{le="2"} 0\na_bucket{le="1"} 0\na_bucket{le="+Inf"} 0\n# EOF\n'),
+                ('# TYPE a histogram\na_bucket{le="1"} 1\na_bucket{le="2"} 1\na_bucket{le="+Inf"} 0\n# EOF\n'),
                 # Bad grouping or ordering.
                 ('# TYPE a histogram\na_sum{a="1"} 0\na_sum{a="2"} 0\na_count{a="1"} 0\n# EOF\n'),
                 ('# TYPE a histogram\na_bucket{a="1",le="1"} 0\na_bucket{a="2",le="+Inf""} 0\na_bucket{a="1",le="+Inf"} 0\n# EOF\n'),