Issue with AttributeKey.type

[jens-at-collectum]

We're using micrometer to instrument the code and AzureMonitorTraceExporter to send traces to Azure's application insight.

As far as I can see there's an issue in how micrometer is bridging cardinalityKeys to otel.

When an observation is stopped, the TracingObservationHandler(s) tags the span with all cardinalityKeys in:

    default void tagSpan(T context, Span span) {
        for (KeyValue keyValue : context.getAllKeyValues()) {
            if (!keyValue.getKey().equalsIgnoreCase("ERROR")) {
                span.tag(keyValue.getKey(), keyValue.getValue());
            }
            else {
                span.error(new RuntimeException(keyValue.getValue()));
            }
        }
    }

However, TracingObservationHandler.spanTag() implicitly converts all AttributeKeys to string keys, spanTag() uses keyValue.getKey() keyValue.getValue(), which will eventually invoke Span.setAttribute(String, String) which creates a string key.

  default Span setAttribute(String key, @Nullable String value) {
    return setAttribute(AttributeKey.stringKey(key), value);
  }

According to otel, should for example ttp.response.status_code be a longKey:

    AttributeKey<Long> HTTP_RESPONSE_STATUS_CODE = longKey("http.response.status_code");

The effect is that AzureMonitor, in this case, is unable to map spans to theit TelemetryItems, and most tags/attributes will be considered custom tags.

[marcingrzejszczak]

I think it's related to micrometer-metrics/micrometer#3781

[jens-at-collectum]

Ah, ok. Didn't notice it was an old issue. Shouldn't this be fixed? In the long run it usually is a good idea to follow standards and conventions.

[jonatan-ivanov]

Right now, as a workaround, you can create and register a SpanFilter to convert the type(s):

SpanFilter azureSpanFilter() {
    return new SpanFilter() {
        @Override
        public FinishedSpan map(FinishedSpan span) {
            if (span.getTags().containsKey("...")) {
                return span.setTypedTags(...);
            }
            return span;
        }
    };
}