stats: Add additional constraints to histogram bucket configuration (#12312)

This ensures that the configuration is valid.

Note that this adds stricter validation to an existing proto field, but the field was only added 5 days ago, so only someone running HEAD, using this new config, with invalid/non-sensical config should be affected.

Signed-off-by: Greg Greenway <ggreenway@apple.com>

Mirrored from https://github.com/envoyproxy/envoy @ 61c2816f704d11f66a507b76abc8f01c1816fe57

envoy/config/metrics/v3/stats.proto

@@ -294,8 +294,13 @@ message HistogramBucketSettings {
   // before tag-extraction, for example `cluster.exampleclustername.upstream_cx_length_ms`.
   type.matcher.v3.StringMatcher match = 1 [(validate.rules).message = {required: true}];
 
-  // Each value is the upper bound of a successive bucket.
-  repeated double buckets = 2 [(validate.rules).repeated = {min_items: 1}];
+  // Each value is the upper bound of a bucket. Each bucket must be greater than 0 and unique.
+  // The order of the buckets does not matter.
+  repeated double buckets = 2 [(validate.rules).repeated = {
+    min_items: 1
+    unique: true
+    items {double {gt: 0.0}}
+  }];
 }
 
 // Stats configuration proto schema for built-in *envoy.stat_sinks.statsd* sink. This sink does not support

envoy/config/metrics/v4alpha/stats.proto

@@ -297,8 +297,13 @@ message HistogramBucketSettings {
   // before tag-extraction, for example `cluster.exampleclustername.upstream_cx_length_ms`.
   type.matcher.v4alpha.StringMatcher match = 1 [(validate.rules).message = {required: true}];
 
-  // Each value is the upper bound of a successive bucket.
-  repeated double buckets = 2 [(validate.rules).repeated = {min_items: 1}];
+  // Each value is the upper bound of a bucket. Each bucket must be greater than 0 and unique.
+  // The order of the buckets does not matter.
+  repeated double buckets = 2 [(validate.rules).repeated = {
+    min_items: 1
+    unique: true
+    items {double {gt: 0.0}}
+  }];
 }
 
 // Stats configuration proto schema for built-in *envoy.stat_sinks.statsd* sink. This sink does not support