Add .NET metrics

.github/CODEOWNERS

@@ -74,3 +74,8 @@
 /model/registry/container.yaml @open-telemetry/specs-semconv-approvers @open-telemetry/semconv-container-approvers
 /model/registry/oci.yaml @open-telemetry/specs-semconv-approvers @open-telemetry/semconv-container-approvers
 
+# .NET semantic conventions approvers
+/model/metrics/dotnet/ @open-telemetry/specs-semconv-approvers @open-telemetry/semconv-dotnet-approvers  @open-telemetry/semconv-http-approvers
+/docs/dotnet/          @open-telemetry/specs-semconv-approvers @open-telemetry/semconv-dotnet-approvers  @open-telemetry/semconv-http-approvers
+
+# TODO - Add semconv area experts

CHANGELOG.md

@@ -24,6 +24,8 @@ release.
   ([#503](https://github.com/open-telemetry/semantic-conventions/pull/503))
 - Add Semantic conventions for TLS/SSL encrypted communication.
   ([#21](https://github.com/open-telemetry/semantic-conventions/pull/21))
+- Add .NET 8.0 metrics for HTTP client, ASP.NET Core, SignalR server and Kestrel.
+  ([#283](https://github.com/open-telemetry/semantic-conventions/pull/283))
 
 ### Fixes
 

docs/dotnet/README.md

@@ -0,0 +1,22 @@
+<!--- Hugo front matter used to generate the website version of this page:
+linkTitle: .NET
+path_base_for_github_subdir:
+  from: content/en/docs/specs/semconv/dotnet/_index.md
+  to: dotnet/README.md
+--->
+
+# Semantic Conventions for .NET metrics
+
+**Status**: [Stable][DocumentStatus]
+
+This article documents semantic conventions for metrics emitted by the .NET runtime and individual components in the .NET ecosystem.
+
+The following metrics are currently supported:
+
+* [ASP.NET Core](dotnet-aspnetcore-metrics.md): Semantic Conventions for ASP.NET Core routing, exceptions, and rate-limiting *metrics*.
+* [DNS](dotnet-dns-metrics.md): Semantic Conventions for client-side DNS lookups associated with *metrics*.
+* [HTTP](dotnet-http-metrics.md): Semantic Conventions for HTTP client and server *metrics*.
+* [Kestrel](dotnet-kestrel-metrics.md): Semantic Conventions for Kestrel web server *metrics*.
+* [SignalR](dotnet-signalr-metrics.md): Semantic Conventions for SignalR server *metrics*.
+
+[DocumentStatus]: https://github.com/open-telemetry/opentelemetry-specification/tree/v1.26.0/specification/document-status.md

docs/dotnet/dotnet-aspnetcore-metrics.md

@@ -0,0 +1,243 @@
+<!--- Hugo front matter used to generate the website version of this page:
+linkTitle: ASP.NET Core
+--->
+
+# Semantic Conventions for ASP.NET Core metrics
+
+**Status**: [Stable][DocumentStatus]
+
+This article defines semantic conventions for ASP.NET Core metrics.
+
+<!-- toc -->
+
+- [Server](#server)
+- [Routing](#routing)
+  * [Metric: `aspnetcore.routing.match_attempts`](#metric-aspnetcoreroutingmatch_attempts)
+- [Exceptions](#exceptions)
+  * [Metric: `aspnetcore.diagnostics.exceptions`](#metric-aspnetcorediagnosticsexceptions)
+- [Rate-limiting](#rate-limiting)
+  * [Metric: `aspnetcore.rate_limiting.active_request_leases`](#metric-aspnetcorerate_limitingactive_request_leases)
+  * [Metric: `aspnetcore.rate_limiting.request_lease.duration`](#metric-aspnetcorerate_limitingrequest_leaseduration)
+  * [Metric: `aspnetcore.rate_limiting.queued_requests`](#metric-aspnetcorerate_limitingqueued_requests)
+  * [Metric: `aspnetcore.rate_limiting.request.time_in_queue`](#metric-aspnetcorerate_limitingrequesttime_in_queue)
+  * [Metric: `aspnetcore.rate_limiting.requests`](#metric-aspnetcorerate_limitingrequests)
+
+<!-- tocstop -->
+
+## Server
+
+## Routing
+
+All routing metrics are reported by the `Microsoft.AspNetCore.Routing` meter.
+
+### Metric: `aspnetcore.routing.match_attempts`
+
+<!-- semconv metric.aspnetcore.routing.match_attempts(metric_table) -->
+| Name     | Instrument Type | Unit (UCUM) | Description    |
+| -------- | --------------- | ----------- | -------------- |
+| `aspnetcore.routing.match_attempts` | Counter | `{match_attempt}` | Number of requests that were attempted to be matched to an endpoint. [1] |
+
+**[1]:** Meter name: `Microsoft.AspNetCore.Routing`; Added in: ASP.NET Core 8.0
+<!-- endsemconv -->
+
+<!-- semconv metric.aspnetcore.routing.match_attempts(full) -->
+| Attribute  | Type | Description  | Examples  | Requirement Level |
+|---|---|---|---|---|
+| `aspnetcore.routing.is_fallback` | boolean | A value that indicates whether the matched route is a fallback route. | `True` | Conditionally Required: if and only if a route was successfully matched. |
+| `aspnetcore.routing.match_status` | string | Match result - success or failure | `success`; `failure` | Required |
+| [`http.route`](../attributes-registry/http.md) | string | The matched route, that is, the path template in the format used by the respective server framework. [1] | `/users/:userID?`; `{controller}/{action}/{id?}` | Conditionally Required: if and only if a route was successfully matched. |
+
+**[1]:** MUST NOT be populated when this is not supported by the HTTP server framework as the route attribute should have low-cardinality and the URI path can NOT substitute it.
+SHOULD include the [application root](/docs/http/http-spans.md#http-server-definitions) if there is one.
+
+`aspnetcore.routing.match_status` has the following list of well-known values. If one of them applies, then the respective value MUST be used, otherwise a custom value MAY be used.
+
+| Value  | Description |
+|---|---|
+| `success` | Match succeeded |
+| `failure` | Match failed |
+<!-- endsemconv -->
+
+## Exceptions
+
+Exceptions Metric is reported by the `Microsoft.AspNetCore.Diagnostics` meter.
+
+### Metric: `aspnetcore.diagnostics.exceptions`
+
+<!-- semconv metric.aspnetcore.diagnostics.exceptions(metric_table) -->
+| Name     | Instrument Type | Unit (UCUM) | Description    |
+| -------- | --------------- | ----------- | -------------- |
+| `aspnetcore.diagnostics.exceptions` | Counter | `{exception}` | Number of exceptions caught by exception handling middleware. [1] |
+
+**[1]:** Meter name: `Microsoft.AspNetCore.Diagnostics`; Added in: ASP.NET Core 8.0
+<!-- endsemconv -->
+
+<!-- semconv metric.aspnetcore.diagnostics.exceptions(full) -->
+| Attribute  | Type | Description  | Examples  | Requirement Level |
+|---|---|---|---|---|
+| `aspnetcore.diagnostics.exception.result` | string | ASP.NET Core exception middleware handling result | `handled`; `unhandled` | Required |
+| `aspnetcore.diagnostics.handler.type` | string | Full type name of the [`IExceptionHandler`](https://learn.microsoft.com/dotnet/api/microsoft.aspnetcore.diagnostics.iexceptionhandler) implementation that handled the exception. | `Contoso.MyHandler` | Conditionally Required: [1] |
+| [`error.type`](../attributes-registry/error.md) | string | The full name of exception type. [2] | `System.OperationCanceledException`; `Contoso.MyException` | Required |
+
+**[1]:** if and only if the exception was handled by this handler.
+
+**[2]:** The `error.type` SHOULD be predictable and SHOULD have low cardinality.
+Instrumentations SHOULD document the list of errors they report.
+
+The cardinality of `error.type` within one instrumentation library SHOULD be low.
+Telemetry consumers that aggregate data from multiple instrumentation libraries and applications
+should be prepared for `error.type` to have high cardinality at query time when no
+additional filters are applied.
+
+If the operation has completed successfully, instrumentations SHOULD NOT set `error.type`.
+
+If a specific domain defines its own set of error identifiers (such as HTTP or gRPC status codes),
+it's RECOMMENDED to:
+
+* Use a domain-specific attribute
+* Set `error.type` to capture all errors, regardless of whether they are defined within the domain-specific set or not.
+
+`aspnetcore.diagnostics.exception.result` MUST be one of the following:
+
+| Value  | Description |
+|---|---|
+| `handled` | Exception was handled by the exception handling middleware. |
+| `unhandled` | Exception was not handled by the exception handling middleware. |
+| `skipped` | Exception handling was skipped because the response had started. |
+| `aborted` | Exception handling didn't run because the request was aborted. |
+
+`error.type` has the following list of well-known values. If one of them applies, then the respective value MUST be used, otherwise a custom value MAY be used.
+
+| Value  | Description |
+|---|---|
+| `_OTHER` | A fallback error value to be used when the instrumentation doesn't define a custom value. |
+<!-- endsemconv -->
+
+## Rate-limiting
+
+All rate-limiting metrics are reported by the `Microsoft.AspNetCore.RateLimiting` meter.
+
+### Metric: `aspnetcore.rate_limiting.active_request_leases`
+
+<!-- semconv metric.aspnetcore.rate_limiting.active_request_leases(metric_table) -->
+| Name     | Instrument Type | Unit (UCUM) | Description    |
+| -------- | --------------- | ----------- | -------------- |
+| `aspnetcore.rate_limiting.active_request_leases` | UpDownCounter | `{request}` | Number of requests that are currently active on the server that hold a rate limiting lease. [1] |
+
+**[1]:** Meter name: `Microsoft.AspNetCore.RateLimiting`; Added in: ASP.NET Core 8.0
+<!-- endsemconv -->
+
+<!-- semconv metric.aspnetcore.rate_limiting.active_request_leases(full) -->
+| Attribute  | Type | Description  | Examples  | Requirement Level |
+|---|---|---|---|---|
+| `aspnetcore.rate_limiting.policy` | string | Rate limiting policy name. | `fixed`; `sliding`; `token` | Conditionally Required: [1] |
+
+**[1]:** if the matched endpoint for the request had a rate-limiting policy.
+<!-- endsemconv -->
+
+### Metric: `aspnetcore.rate_limiting.request_lease.duration`
+
+this metric SHOULD be specified with
+[`ExplicitBucketBoundaries`](https://github.com/open-telemetry/opentelemetry-specification/tree/v1.26.0/specification/metrics/api.md#instrument-advisory-parameters)
+of `[ 0.005, 0.01, 0.025, 0.05, 0.075, 0.1, 0.25, 0.5, 0.75, 1, 2.5, 5, 7.5, 10 ]`.
+
+<!-- semconv metric.aspnetcore.rate_limiting.request_lease.duration(metric_table) -->
+| Name     | Instrument Type | Unit (UCUM) | Description    |
+| -------- | --------------- | ----------- | -------------- |
+| `aspnetcore.rate_limiting.request_lease.duration` | Histogram | `s` | The duration of rate limiting lease held by requests on the server. [1] |
+
+**[1]:** Meter name: `Microsoft.AspNetCore.RateLimiting`; Added in: ASP.NET Core 8.0
+<!-- endsemconv -->
+
+<!-- semconv metric.aspnetcore.rate_limiting.request_lease.duration(full) -->
+| Attribute  | Type | Description  | Examples  | Requirement Level |
+|---|---|---|---|---|
+| `aspnetcore.rate_limiting.policy` | string | Rate limiting policy name. | `fixed`; `sliding`; `token` | Conditionally Required: [1] |
+
+**[1]:** if the matched endpoint for the request had a rate-limiting policy.
+<!-- endsemconv -->
+
+### Metric: `aspnetcore.rate_limiting.queued_requests`
+
+<!-- semconv metric.aspnetcore.rate_limiting.queued_requests(metric_table) -->
+| Name     | Instrument Type | Unit (UCUM) | Description    |
+| -------- | --------------- | ----------- | -------------- |
+| `aspnetcore.rate_limiting.queued_requests` | UpDownCounter | `{request}` | Number of requests that are currently queued, waiting to acquire a rate limiting lease. [1] |
+
+**[1]:** Meter name: `Microsoft.AspNetCore.RateLimiting`; Added in: ASP.NET Core 8.0
+<!-- endsemconv -->
+
+<!-- semconv metric.aspnetcore.rate_limiting.queued_requests(full) -->
+| Attribute  | Type | Description  | Examples  | Requirement Level |
+|---|---|---|---|---|
+| `aspnetcore.rate_limiting.policy` | string | Rate limiting policy name. | `fixed`; `sliding`; `token` | Conditionally Required: [1] |
+
+**[1]:** if the matched endpoint for the request had a rate-limiting policy.
+<!-- endsemconv -->
+
+### Metric: `aspnetcore.rate_limiting.request.time_in_queue`
+
+this metric SHOULD be specified with
+[`ExplicitBucketBoundaries`](https://github.com/open-telemetry/opentelemetry-specification/tree/v1.26.0/specification/metrics/api.md#instrument-advisory-parameters)
+of `[ 0.005, 0.01, 0.025, 0.05, 0.075, 0.1, 0.25, 0.5, 0.75, 1, 2.5, 5, 7.5, 10 ]`.
+
+<!-- semconv metric.aspnetcore.rate_limiting.request.time_in_queue(metric_table) -->
+| Name     | Instrument Type | Unit (UCUM) | Description    |
+| -------- | --------------- | ----------- | -------------- |
+| `aspnetcore.rate_limiting.request.time_in_queue` | Histogram | `s` | The time the request spent in a queue waiting to acquire a rate limiting lease. [1] |
+
+**[1]:** Meter name: `Microsoft.AspNetCore.RateLimiting`; Added in: ASP.NET Core 8.0
+<!-- endsemconv -->
+
+<!-- semconv metric.aspnetcore.rate_limiting.request.time_in_queue(full) -->
+| Attribute  | Type | Description  | Examples  | Requirement Level |
+|---|---|---|---|---|
+| `aspnetcore.rate_limiting.policy` | string | Rate limiting policy name. | `fixed`; `sliding`; `token` | Conditionally Required: [1] |
+| `aspnetcore.rate_limiting.result` | string | Rate-limiting result, shows whether the lease was acquired or contains a rejection reason | `acquired`; `request_canceled` | Required |
+
+**[1]:** if the matched endpoint for the request had a rate-limiting policy.
+
+`aspnetcore.rate_limiting.result` has the following list of well-known values. If one of them applies, then the respective value MUST be used, otherwise a custom value MAY be used.
+
+| Value  | Description |
+|---|---|
+| `acquired` | Lease was acquired |
+| `endpoint_limiter` | Lease request was rejected by the endpoint limiter |
+| `global_limiter` | Lease request was rejected by the global limiter |
+| `request_canceled` | Lease request was canceled |
+<!-- endsemconv -->
+
+### Metric: `aspnetcore.rate_limiting.requests`
+
+<!-- semconv metric.aspnetcore.rate_limiting.requests(metric_table) -->
+| Name     | Instrument Type | Unit (UCUM) | Description    |
+| -------- | --------------- | ----------- | -------------- |
+| `aspnetcore.rate_limiting.requests` | Counter | `{request}` | Number of requests that tried to acquire a rate limiting lease. [1] |
+
+**[1]:** Requests could be:
+
+* Rejected by global or endpoint rate limiting policies
+* Canceled while waiting for the lease.
+
+Meter name: `Microsoft.AspNetCore.RateLimiting`; Added in: ASP.NET Core 8.0
+<!-- endsemconv -->
+
+<!-- semconv metric.aspnetcore.rate_limiting.requests(full) -->
+| Attribute  | Type | Description  | Examples  | Requirement Level |
+|---|---|---|---|---|
+| `aspnetcore.rate_limiting.policy` | string | Rate limiting policy name. | `fixed`; `sliding`; `token` | Conditionally Required: [1] |
+| `aspnetcore.rate_limiting.result` | string | Rate-limiting result, shows whether the lease was acquired or contains a rejection reason | `acquired`; `request_canceled` | Required |
+
+**[1]:** if the matched endpoint for the request had a rate-limiting policy.
+
+`aspnetcore.rate_limiting.result` has the following list of well-known values. If one of them applies, then the respective value MUST be used, otherwise a custom value MAY be used.
+
+| Value  | Description |
+|---|---|
+| `acquired` | Lease was acquired |
+| `endpoint_limiter` | Lease request was rejected by the endpoint limiter |
+| `global_limiter` | Lease request was rejected by the global limiter |
+| `request_canceled` | Lease request was canceled |
+<!-- endsemconv -->
+
+[DocumentStatus]: https://github.com/open-telemetry/opentelemetry-specification/tree/v1.26.0/specification/document-status.md

docs/dotnet/dotnet-dns-metrics.md

@@ -0,0 +1,60 @@
+<!--- Hugo front matter used to generate the website version of this page:
+linkTitle: DNS
+--->
+
+# Semantic Conventions for DNS metrics emitted by .NET
+
+**Status**: [Stable][DocumentStatus]
+
+This article defines semantic conventions for DNS metrics emitted by .NET.
+
+<!-- toc -->
+
+- [DNS metrics](#dns-metrics)
+  * [Metric: `dns.lookup.duration`](#metric-dnslookupduration)
+
+<!-- tocstop -->
+
+## DNS metrics
+
+### Metric: `dns.lookup.duration`
+
+this metric SHOULD be specified with
+[`ExplicitBucketBoundaries`](https://github.com/open-telemetry/opentelemetry-specification/tree/v1.26.0/specification/metrics/api.md#instrument-advisory-parameters)
+of `[ 0.005, 0.01, 0.025, 0.05, 0.075, 0.1, 0.25, 0.5, 0.75, 1, 2.5, 5, 7.5, 10 ]`.
+
+<!-- semconv metric.dotnet.dns.lookup.duration(metric_table) -->
+| Name     | Instrument Type | Unit (UCUM) | Description    |
+| -------- | --------------- | ----------- | -------------- |
+| `dns.lookup.duration` | Histogram | `s` | Measures the time taken to perform a DNS lookup. [1] |
+
+**[1]:** Meter name: `System.Net.NameResolution`; Added in: .NET 8.0
+<!-- endsemconv -->
+
+<!-- semconv metric.dotnet.dns.lookup.duration(full) -->
+| Attribute  | Type | Description  | Examples  | Requirement Level |
+|---|---|---|---|---|
+| `dns.question.name` | string | The name being queried. [1] | `www.example.com`; `dot.net` | Required |
+| [`error.type`](../attributes-registry/error.md) | string | One of the resolution errors or the full name of exception type. [2] | `host_not_found`; `no_recovery`; `System.Net.Sockets.SocketException` | Conditionally Required: if and only if an error has occurred. |
+
+**[1]:** The name being queried.
+If the name field contains non-printable characters (below 32 or above 126), those characters should be represented as escaped base 10 integers (\DDD). Back slashes and quotes should be escaped. Tabs, carriage returns, and line feeds should be converted to \t, \r, and \n respectively.
+
+**[2]:** The following errors codes are reported:
+
+- "host_not_found"
+- "try_again"
+- "address_family_not_supported"
+- "no_recovery"
+
+See [SocketError](https://learn.microsoft.com/dotnet/api/system.net.sockets.socketerror)
+for more details.
+
+`error.type` has the following list of well-known values. If one of them applies, then the respective value MUST be used, otherwise a custom value MAY be used.
+
+| Value  | Description |
+|---|---|
+| `_OTHER` | A fallback error value to be used when the instrumentation doesn't define a custom value. |
+<!-- endsemconv -->
+
+[DocumentStatus]: https://github.com/open-telemetry/opentelemetry-specification/tree/v1.26.0/specification/document-status.md