[ASP.NET Core] Add error.type attribute for tracing and metrics

[vishweshbankwar]

Fixes #
Design discussion issue #

Changes

Adds error.type attribute to trace and metrics.

https://github.com/open-telemetry/semantic-conventions/blob/main/docs/http/http-metrics.md
https://github.com/open-telemetry/semantic-conventions/blob/main/docs/http/http-spans.md

.NET8.0 implementation of metrics ignores setting error.type to status code value in case of failure as per the spec. I have opened an issue to get this fixed dotnet/aspnetcore#51620. For now, the issue is targeted to be fixed in .NET9.0.

The change in this PR ensures that the value is consistent with how .NET8.0 is setting this attribute in metrics in order to avoid breaking change for users migrating from lower versions to .NET8.0.

This change does not resolve
#4865

Merge requirement checklist

• CONTRIBUTING guidelines followed (nullable enabled, static analysis, etc.)
• Unit tests added/updated
• Appropriate CHANGELOG.md files updated for non-trivial changes
• Changes in public API reviewed (if applicable)

[codecov]

Codecov Report

Merging #4986 (b59075c) into main (37481f1) will increase coverage by 0.05%.
The diff coverage is 91.30%.

@@            Coverage Diff             @@
##             main    #4986      +/-   ##
==========================================
+ Coverage   83.38%   83.43%   +0.05%     
==========================================
  Files         296      296              
  Lines       12385    12403      +18     
==========================================
+ Hits        10327    10349      +22     
+ Misses       2058     2054       -4     

Flag	Coverage Δ
unittests	83.43% <91.30%> (+0.05%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files	Coverage Δ
...ry.Instrumentation.AspNetCore/AspNetCoreMetrics.cs	100.00% <100.00%> (ø)
...tation.AspNetCore/Implementation/HttpInListener.cs	91.87% <100.00%> (+0.08%)	⬆️
...AspNetCore/Implementation/HttpInMetricsListener.cs	86.95% <89.47%> (-0.32%)	⬇️

... and 5 files with indirect coverage changes

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[TimothyMothra]

On the whole looks good. Left some minor comments.

[utpilla]

Would the framework create an activity even if only add AspNetCore metrics instrumentation? If yes, then I think we could add this information to Activity.Current. Do you know of any obvious pros and cons to adding this information to HttpContext vs Activity.Current?

[vishweshbankwar]

yes, the activity will always be there. Perf was the main reason to choose HttpContext.Items. However, we could use custom property as well on activity. Here are the results from benchmarking

Results when trace is also enabled and activity will have additional tags.

Method	Mean	Error	StdDev	Median	Gen0	Allocated
UseActivityTag	82.36 ns	1.691 ns	1.736 ns	83.06 ns	0.0085	40 B
UseActivityCustomProperty	81.98 ns	1.133 ns	1.004 ns	81.54 ns	-	-
UseContextItems	81.11 ns	1.656 ns	3.420 ns	79.67 ns	-	-

Results when only metrics will be enabled and activity will only have one tag

Method	Mean	Error	StdDev	Gen0	Allocated
UseActivityTag	55.56 ns	0.572 ns	0.535 ns	0.0085	40 B
UseActivityCustomProperty	80.94 ns	0.538 ns	0.477 ns	-	-
UseContextItems	80.50 ns	0.901 ns	0.843 ns	-	-

Based on above, I have updated the implementation to use custom property. We could follow the same thing on HttpClient side where we need to add error.type.

[CodeBlanch]

IIRC the first time you add a custom property to activity you pay for an allocation. Are we already adding one somewhere else? Seems a bit odd that the allocation isn't showing in the benchmark.

[vishweshbankwar]

@CodeBlanch Good catch. The alloc is not showing up in the benchmark as it is getting ignored due to multiple runs. I have switched back to using context.items and it improved the look up as well using the minor tweak on the context key suggested by you. here are the results.

Method	Mean	Error	StdDev	Gen0	Allocated
UseActivityTag	56.93 ns	0.572 ns	0.446 ns	0.0085	40 B
UseActivityCustomProperty	83.61 ns	0.546 ns	0.511 ns	-	-
UseContextItemsObjectKey	68.49 ns	0.429 ns	0.401 ns	-	-
UseContextItemsStringKey	84.91 ns	1.191 ns	0.994 ns	-	-

[CodeBlanch]

Let's add a Debug.Assert(activity != null) here. I'm paranoid 🤣

[vishweshbankwar]

we have a check here

[CodeBlanch]

LGTM