fix: validate scale range and raise exception if out of bounds (#1865)

* fix: add check to make sure scale is within the valid range

* revision

---------

Co-authored-by: Kayla Reopelle <[email protected]>

Author: xuan-cao-swi

metrics_sdk/lib/opentelemetry/sdk/metrics/aggregation/exponential_bucket_histogram.rb

@@ -19,15 +19,18 @@ class ExponentialBucketHistogram # rubocop:disable Metrics/ClassLength
           attr_reader :aggregation_temporality
 
           # relate to min max scale: https://opentelemetry.io/docs/specs/otel/metrics/sdk/#support-a-minimum-and-maximum-scale
+          DEFAULT_SIZE  = 160
+          DEFAULT_SCALE = 20
           MAX_SCALE = 20
           MIN_SCALE = -10
-          MAX_SIZE  = 160
+          MIN_MAX_SIZE = 2
+          MAX_MAX_SIZE = 16_384
 
           # The default boundaries are calculated based on default max_size and max_scale values
           def initialize(
             aggregation_temporality: ENV.fetch('OTEL_EXPORTER_OTLP_METRICS_TEMPORALITY_PREFERENCE', :delta),
-            max_size: MAX_SIZE,
-            max_scale: MAX_SCALE,
+            max_size: DEFAULT_SIZE,
+            max_scale: DEFAULT_SCALE,
             record_min_max: true,
             zero_threshold: 0
           )
@@ -175,6 +178,7 @@ def grow_buckets(span, buckets)
           end
 
           def new_mapping(scale)
+            scale = validate_scale(scale)
             scale <= 0 ? ExponentialHistogram::ExponentMapping.new(scale) : ExponentialHistogram::LogarithmMapping.new(scale)
           end
 
@@ -203,17 +207,17 @@ def downscale(change, positive, negative)
           end
 
           def validate_scale(scale)
-            return scale unless scale > MAX_SCALE || scale < MIN_SCALE
+            raise ArgumentError, "Scale #{scale} is larger than maximum scale #{MAX_SCALE}" if scale > MAX_SCALE
+            raise ArgumentError, "Scale #{scale} is smaller than minimum scale #{MIN_SCALE}" if scale < MIN_SCALE
 
-            OpenTelemetry.logger.warn "Scale #{scale} is invalid, using default max scale #{MAX_SCALE}"
-            MAX_SCALE
+            scale
           end
 
           def validate_size(size)
-            return size unless size > MAX_SIZE || size < 0
+            raise ArgumentError, "Max size #{size} is smaller than minimum size #{MIN_MAX_SIZE}" if size < MIN_MAX_SIZE
+            raise ArgumentError, "Max size #{size} is larger than maximum size #{MAX_MAX_SIZE}" if size > MAX_MAX_SIZE
 
-            OpenTelemetry.logger.warn "Size #{size} is invalid, using default max size #{MAX_SIZE}"
-            MAX_SIZE
+            size
           end
         end
       end

metrics_sdk/test/opentelemetry/sdk/metrics/aggregation/exponential_bucket_histogram_test.rb

@@ -255,5 +255,29 @@
     it 'test_merge' do
       # TODO
     end
+
+    it 'test_invalid_scale_validation' do
+      error = assert_raises(ArgumentError) do
+        OpenTelemetry::SDK::Metrics::Aggregation::ExponentialBucketHistogram.new(max_scale: 100)
+      end
+      assert_equal('Scale 100 is larger than maximum scale 20', error.message)
+
+      error = assert_raises(ArgumentError) do
+        OpenTelemetry::SDK::Metrics::Aggregation::ExponentialBucketHistogram.new(max_scale: -20)
+      end
+      assert_equal('Scale -20 is smaller than minimum scale -10', error.message)
+    end
+
+    it 'test_invalid_size_validation' do
+      error = assert_raises(ArgumentError) do
+        OpenTelemetry::SDK::Metrics::Aggregation::ExponentialBucketHistogram.new(max_size: 10_000_000)
+      end
+      assert_equal('Max size 10000000 is larger than maximum size 16384', error.message)
+
+      error = assert_raises(ArgumentError) do
+        OpenTelemetry::SDK::Metrics::Aggregation::ExponentialBucketHistogram.new(max_size: 0)
+      end
+      assert_equal('Max size 0 is smaller than minimum size 2', error.message)
+    end
   end
 end