Semantic Conventions for ASP.NET Core metrics
Status: Stable
This article defines semantic conventions for ASP.NET Core metrics.
Server
Routing
All routing metrics are reported by the Microsoft.AspNetCore.Routing meter.
Metric: aspnetcore.routing.match_attempts
| Name | Instrument Type | Unit (UCUM) | Description | Stability |
|---|---|---|---|---|
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
| Attribute | Type | Description | Examples | Requirement Level | Stability |
|---|---|---|---|---|---|
aspnetcore.routing.match_status | string | Match result - success or failure | success; failure | Required | |
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. | |
http.route | 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 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 | Stability |
|---|---|---|
success | Match succeeded | |
failure | Match failed | |
Exceptions
Exceptions Metric is reported by the Microsoft.AspNetCore.Diagnostics meter.
Metric: aspnetcore.diagnostics.exceptions
| Name | Instrument Type | Unit (UCUM) | Description | Stability |
|---|---|---|---|---|
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
| Attribute | Type | Description | Examples | Requirement Level | Stability |
|---|---|---|---|---|---|
aspnetcore.diagnostics.exception.result | string | ASP.NET Core exception middleware handling result | handled; unhandled | Required | |
error.type | string | The full name of exception type. [1] | System.OperationCanceledException; Contoso.MyException | Required | |
aspnetcore.diagnostics.handler.type | string | Full type name of the IExceptionHandler implementation that handled the exception. | Contoso.MyHandler | Conditionally Required [2] | |
[1]: 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.typeto capture all errors, regardless of whether they are defined within the domain-specific set or not.
[2]: if and only if the exception was handled by this handler.
aspnetcore.diagnostics.exception.result MUST be one of the following:
| Value | Description | Stability |
|---|---|---|
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 | Stability |
|---|---|---|
_OTHER | A fallback error value to be used when the instrumentation doesn’t define a custom value. | |
Rate-limiting
All rate-limiting metrics are reported by the Microsoft.AspNetCore.RateLimiting meter.
Metric: aspnetcore.rate_limiting.active_request_leases
| Name | Instrument Type | Unit (UCUM) | Description | Stability |
|---|---|---|---|---|
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
| Attribute | Type | Description | Examples | Requirement Level | Stability |
|---|---|---|---|---|---|
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.
Metric: aspnetcore.rate_limiting.request_lease.duration
this metric SHOULD be specified with
ExplicitBucketBoundaries
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 ].
| Name | Instrument Type | Unit (UCUM) | Description | Stability |
|---|---|---|---|---|
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
| Attribute | Type | Description | Examples | Requirement Level | Stability |
|---|---|---|---|---|---|
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.
Metric: aspnetcore.rate_limiting.queued_requests
| Name | Instrument Type | Unit (UCUM) | Description | Stability |
|---|---|---|---|---|
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
| Attribute | Type | Description | Examples | Requirement Level | Stability |
|---|---|---|---|---|---|
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.
Metric: aspnetcore.rate_limiting.request.time_in_queue
this metric SHOULD be specified with
ExplicitBucketBoundaries
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 ].
| Name | Instrument Type | Unit (UCUM) | Description | Stability |
|---|---|---|---|---|
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
| Attribute | Type | Description | Examples | Requirement Level | Stability |
|---|---|---|---|---|---|
aspnetcore.rate_limiting.result | string | Rate-limiting result, shows whether the lease was acquired or contains a rejection reason | acquired; request_canceled | Required | |
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.
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 | Stability |
|---|---|---|
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 | |
Metric: aspnetcore.rate_limiting.requests
| Name | Instrument Type | Unit (UCUM) | Description | Stability |
|---|---|---|---|---|
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
| Attribute | Type | Description | Examples | Requirement Level | Stability |
|---|---|---|---|---|---|
aspnetcore.rate_limiting.result | string | Rate-limiting result, shows whether the lease was acquired or contains a rejection reason | acquired; request_canceled | Required | |
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.
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 | Stability |
|---|---|---|
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 | |