Fix metrics attribute types

Metrics attributes were being coerced to strings. This is now fixed.
In addition, the logic around types accepted as metrics attributes has been simplified. It will log and ignore values of the wrong type.

Fixes #3691

.changesets/fix_bryn_fix_metrics_typing.md

@@ -0,0 +1,6 @@
+### Fix metrics attribute types ([Issue #3687](https://github.com/apollographql/router/issues/3687))
+
+Metrics attributes were being coerced to strings. This is now fixed.
+In addition, the logic around types accepted as metrics attributes has been simplified. It will log and ignore values of the wrong type.
+
+By [@BrynCooke](https://github.com/BrynCooke) in https://github.com/apollographql/router/pull/3701

apollo-router/src/plugins/telemetry/metrics/layer.rs

@@ -177,7 +177,10 @@ impl<'a> Visit for MetricVisitor<'a> {
 
     fn record_i64(&mut self, field: &Field, value: i64) {
         if let Some(metric_name) = field.name().strip_prefix(METRIC_PREFIX_MONOTONIC_COUNTER) {
-            tracing::error!(metric_name, "monotonic counter must be u64");
+            tracing::error!(
+                metric_name,
+                "monotonic counter must be u64, this metric will be ignored"
+            );
         } else if let Some(metric_name) = field.name().strip_prefix(METRIC_PREFIX_COUNTER) {
             self.metric = Some((metric_name, InstrumentType::UpDownCounterI64(value)));
         } else if let Some(metric_name) = field.name().strip_prefix(METRIC_PREFIX_HISTOGRAM) {
@@ -201,11 +204,17 @@ impl<'a> Visit for MetricVisitor<'a> {
     }
 
     fn record_i128(&mut self, field: &Field, _value: i128) {
-        tracing::error!(name = field.name(), "metric attribute cannot be i128");
+        tracing::error!(
+            name = field.name(),
+            "metric attribute cannot be i128, this attribute will be ignored"
+        );
     }
 
     fn record_u128(&mut self, field: &Field, _value: u128) {
-        tracing::error!(name = field.name(), "metric attribute cannot be u128");
+        tracing::error!(
+            name = field.name(),
+            "metric attribute cannot be u128, this attribute will be ignored"
+        );
     }
 
     fn record_bool(&mut self, field: &Field, value: bool) {