config.md

Configuration

Configuration methods

You can apply configuration settings in the following ways, with environment variables taking precedence over App.config or Web.config file:

1. Environment variables

   Environment variables are the main way to configure the settings.

2. App.config or Web.config file

   For an application running on .NET Framework, you can use a web configuration file (web.config) or an application configuration file (app.config) to configure the OTEL_* settings.

   ⚠️ Only settings starting with OTEL_ can be set using App.config or Web.config. However, the following settings are not supported:

   • OTEL_DOTNET_AUTO_HOME
   • OTEL_DOTNET_AUTO_EXCLUDE_PROCESSES
   • OTEL_DOTNET_AUTO_FAIL_FAST_ENABLED
   • OTEL_DOTNET_AUTO_[TRACES|METRICS|LOGS]_INSTRUMENTATION_ENABLED
   • OTEL_DOTNET_AUTO_[TRACES|METRICS|LOGS]_{INSTRUMENTATION_ID}_INSTRUMENTATION_ENABLED
   • OTEL_DOTNET_AUTO_LOG_DIRECTORY
   • OTEL_LOG_LEVEL
   • OTEL_DOTNET_AUTO_NETFX_REDIRECT_ENABLED

   Example with OTEL_SERVICE_NAME setting:

   <configuration>
   <appSettings>
       <add key="OTEL_SERVICE_NAME" value="my-service-name" />
   </appSettings>
   </configuration>

3. Service name automatic detection

   If no service name is explicitly configured one will be generated for you. This can be helpful in some circumstances.

   • If the application is hosted on IIS in .NET Framework this will be SiteName\VirtualPath ex: MySite\MyApp
   • If that is not the case it will use the name of the application entry Assembly.

By default we recommend using environment variables for configuration. However, if given setting supports it, then:

• use Web.config for configuring an ASP.NET application (.NET Framework),
• use App.config for configuring a Windows Service (.NET Framework).

Global settings

Environment variable	Description	Default value	Status
OTEL_DOTNET_AUTO_HOME	Installation location.		Experimental
OTEL_DOTNET_AUTO_EXCLUDE_PROCESSES	Names of the executable files that the profiler cannot instrument. Supports multiple comma-separated values, for example: ReservedProcess.exe,powershell.exe. If unset, the profiler attaches to all processes by default. [1][2]		Experimental
OTEL_DOTNET_AUTO_FAIL_FAST_ENABLED	Enables possibility to fail process when automatic instrumentation cannot be executed. It is designed for debugging purposes. It should not be used in production environment. [1]	false	Experimental
OTEL_DOTNET_AUTO_LOGGER	AutoInstrumentation diagnostic logs sink. (supported values: none,file,console)	file	Experimental
OTEL_LOG_LEVEL	SDK log level. (supported values: none,error,warn,info,debug)	info	Stable

[1] If OTEL_DOTNET_AUTO_FAIL_FAST_ENABLED is set to true then processes excluded from instrumentation by OTEL_DOTNET_AUTO_EXCLUDE_PROCESSES will fail instead of silently continue. [2] Notice that applications launched via dotnet MyApp.dll have process name dotnet or dotnet.exe.

Resources

A resource is the immutable representation of the entity producing the telemetry. See Resource semantic conventions for more details.

Resource attributes

Environment variable	Description	Default value	Status
OTEL_RESOURCE_ATTRIBUTES	Key-value pairs to be used as resource attributes. See Resource SDK for more details.	See Resource semantic conventions for details.	Stable
OTEL_SERVICE_NAME	Sets the value of the service.name resource attribute. If service.name is provided in OTEL_RESOURCE_ATTRIBUTES, the value of OTEL_SERVICE_NAME takes precedence.	See Service name automatic detection under Configuration method section.	Stable

Resource detectors

Environment variable	Description	Default value	Status
OTEL_DOTNET_AUTO_RESOURCE_DETECTOR_ENABLED	Enables all resource detectors.	true	Experimental
OTEL_DOTNET_AUTO_{0}_RESOURCE_DETECTOR_ENABLED	Configuration pattern for enabling a specific resource detector, where {0} is the uppercase id of the resource detector you want to enable. Overrides OTEL_DOTNET_AUTO_RESOURCE_DETECTOR_ENABLED.	true	Experimental

The following resource detectors are included and enabled by default:

ID	Description	Documentation	Status
AZUREAPPSERVICE	Azure App Service detector	Azure resource detector documentation	Experimental
CONTAINER	Container detector	Container resource detector documentation Not supported on .NET Framework	Experimental
HOST	Host detector	Host resource detector documentation	Experimental
OPERATINGSYSTEM	Operating System detector	Operating System resource detector documentation	Experimental
PROCESS	Process detector	Process resource detector documentation	Experimental
PROCESSRUNTIME	Process Runtime detector	Process Runtime resource detector documentation	Experimental

Instrumentations

All instrumentations are enabled by default for all signal types (traces, metrics, and logs).

You can disable all instrumentations for a specific signal type by setting the OTEL_DOTNET_AUTO_{SIGNAL}_INSTRUMENTATION_ENABLED environment variable to false.

For a more granular approach, you can disable specific instrumentations for a given signal type by setting the OTEL_DOTNET_AUTO_{SIGNAL}_{0}_INSTRUMENTATION_ENABLED environment variable to false, where {SIGNAL} is the type of signal, for example TRACES, and {0} is the case-sensitive name of the instrumentation.

Environment variable	Description	Default value	Status
OTEL_DOTNET_AUTO_INSTRUMENTATION_ENABLED	Enables all instrumentations.	true	Experimental
OTEL_DOTNET_AUTO_TRACES_INSTRUMENTATION_ENABLED	Enables all trace instrumentations. Overrides OTEL_DOTNET_AUTO_INSTRUMENTATION_ENABLED.	Inherited from the current value of OTEL_DOTNET_AUTO_INSTRUMENTATION_ENABLED	Experimental
OTEL_DOTNET_AUTO_TRACES_{0}_INSTRUMENTATION_ENABLED	Configuration pattern for enabling a specific trace instrumentation, where {0} is the uppercase id of the instrumentation you want to enable. Overrides OTEL_DOTNET_AUTO_TRACES_INSTRUMENTATION_ENABLED.	Inherited from the current value of OTEL_DOTNET_AUTO_TRACES_INSTRUMENTATION_ENABLED	Experimental
OTEL_DOTNET_AUTO_METRICS_INSTRUMENTATION_ENABLED	Disables all metric instrumentations. Overrides OTEL_DOTNET_AUTO_INSTRUMENTATION_ENABLED.	Inherited from the current value of OTEL_DOTNET_AUTO_INSTRUMENTATION_ENABLED	Experimental
OTEL_DOTNET_AUTO_METRICS_{0}_INSTRUMENTATION_ENABLED	Configuration pattern for enabling a specific metric instrumentation, where {0} is the uppercase id of the instrumentation you want to enable. Overrides OTEL_DOTNET_AUTO_METRICS_INSTRUMENTATION_ENABLED.	Inherited from the current value of OTEL_DOTNET_AUTO_METRICS_INSTRUMENTATION_ENABLED	Experimental
OTEL_DOTNET_AUTO_LOGS_INSTRUMENTATION_ENABLED	Disables all log instrumentations. Overrides OTEL_DOTNET_AUTO_INSTRUMENTATION_ENABLED.	Inherited from the current value of OTEL_DOTNET_AUTO_INSTRUMENTATION_ENABLED	Experimental
OTEL_DOTNET_AUTO_LOGS_{0}_INSTRUMENTATION_ENABLED	Configuration pattern for enabling a specific log instrumentation, where {0} is the uppercase id of the instrumentation you want to enable. Overrides OTEL_DOTNET_AUTO_LOGS_INSTRUMENTATION_ENABLED.	Inherited from the current value of OTEL_DOTNET_AUTO_LOGS_INSTRUMENTATION_ENABLED	Experimental

Traces instrumentations

Status: Mixed. Traces are stable, but particular instrumentation are in Experimental status due to lack of stable semantic convention.

ID	Instrumented library	Supported versions	Instrumentation type	Status
ASPNET	ASP.NET (.NET Framework) MVC / WebApi [1] Not supported on .NET	* [2]	source & bytecode	Experimental
ASPNETCORE	ASP.NET Core Not supported on .NET Framework	*	source	Experimental
AZURE	Azure SDK	[3]	source	Experimental
ELASTICSEARCH	Elastic.Clients.Elasticsearch	* [4]	source	Experimental
ELASTICTRANSPORT	Elastic.Transport	≥0.4.16	source	Experimental
ENTITYFRAMEWORKCORE	Microsoft.EntityFrameworkCore Not supported on .NET Framework	≥6.0.12	source	Experimental
GRAPHQL	GraphQL Not supported on .NET Framework	≥7.5.0	source	Experimental
GRPCNETCLIENT	Grpc.Net.Client	≥2.52.0 & < 3.0.0	source	Experimental
HTTPCLIENT	System.Net.Http.HttpClient and System.Net.HttpWebRequest	*	source	Experimental
KAFKA	Confluent.Kafka	≥1.4.0 & < 3.0.0 [5]	bytecode	Experimental
MASSTRANSIT	MassTransit Not supported on .NET Framework	≥8.0.0	source	Experimental
MONGODB	MongoDB.Driver.Core	≥2.28.0 & < 3.0.0	source & bytecode	Experimental
MYSQLCONNECTOR	MySqlConnector	≥2.0.0	source	Experimental
MYSQLDATA	MySql.Data Not supported on .NET Framework	≥8.1.0	source	Experimental
NPGSQL	Npgsql	≥6.0.0	source	Experimental
NSERVICEBUS	NServiceBus	≥8.0.0 & < 10.0.0	source & bytecode	Experimental
ORACLEMDA	Oracle.ManagedDataAccess.Core and Oracle.ManagedDataAccess Not supported on ARM64	≥23.4.0	source	Experimental
RABBITMQ	RabbitMQ.Client	≥6.0.0 & < 7.0.0	bytecode	Experimental
QUARTZ	Quartz Not supported on .NET Framework 4.7.1 and older	≥3.4.0	source	Experimental
SQLCLIENT	Microsoft.Data.SqlClient, System.Data.SqlClient and System.Data (shipped with .NET Framework)	* [6]	source	Experimental
STACKEXCHANGEREDIS	StackExchange.Redis Not supported on .NET Framework	≥2.6.122 & < 3.0.0	source & bytecode	Experimental
WCFCLIENT	WCF	*	source & bytecode	Experimental
WCFSERVICE	WCF Not supported on .NET.	*	source & bytecode	Experimental

[1]: Only integrated pipeline mode is supported.

[2]: ASP.NET (.NET Framework) MVC / WebApi is not supported on ARM64.

[3]: Azure. prefixed packages, released after October 1, 2021.

[4]: Elastic.Clients.Elasticsearch version ≥8.0.0 and <8.10.0. Version ≥8.10.0 is supported by Elastic.Transport instrumentation.

[5]: Confluent.Kafka is supported from version ≥1.8.2 on ARM64.

[6]: Microsoft.Data.SqlClient v3.* is not supported on .NET Framework, due to issue. System.Data.SqlClient is supported from version 4.8.5.

Metrics instrumentations

Status: Mixed. Metrics are stable, but particular instrumentation are in Experimental status due to lack of stable semantic convention.

ID	Instrumented library	Documentation	Supported versions	Instrumentation type	Status
ASPNET	ASP.NET Framework [1] Not supported on .NET	ASP.NET metrics	*	source & bytecode	Experimental
ASPNETCORE	ASP.NET Core [2] Not supported on .NET Framework	ASP.NET Core metrics	*	source	Experimental
HTTPCLIENT	System.Net.Http.HttpClient and System.Net.HttpWebRequest	HttpClient metrics	*	source	Experimental
NETRUNTIME	OpenTelemetry.Instrumentation.Runtime	Runtime metrics	*	source	Experimental
PROCESS	OpenTelemetry.Instrumentation.Process	Process metrics	*	source	Experimental
NSERVICEBUS	NServiceBus	NServiceBus metrics	≥8.0.0 & < 10.0.0	source & bytecode	Experimental

[1]: The ASP.NET metrics are generated only if the AspNet trace instrumentation is also enabled.

[2]: This instrumentation automatically enables the Microsoft.AspNetCore.Hosting.HttpRequestIn spans.

Logs instrumentations

Status: Experimental.

ID	Instrumented library	Supported versions	Instrumentation type	Status
ILOGGER	Microsoft.Extensions.Logging Not supported on .NET Framework	≥8.0.0	bytecode or source [1]	Experimental

[1]: For ASP.NET Core applications, the LoggingBuilder instrumentation can be enabled without using the .NET CLR Profiler by setting the ASPNETCORE_HOSTINGSTARTUPASSEMBLIES environment variable to OpenTelemetry.AutoInstrumentation.AspNetCoreBootstrapper.

Instrumentation options

Environment variable	Description	Default value	Status
OTEL_DOTNET_AUTO_ENTITYFRAMEWORKCORE_SET_DBSTATEMENT_FOR_TEXT	Whether the Entity Framework Core instrumentation can pass SQL statements through the db.statement attribute. Queries might contain sensitive information. If set to false, db.statement is recorded only for executing stored procedures.	false	Experimental
OTEL_DOTNET_AUTO_GRAPHQL_SET_DOCUMENT	Whether the GraphQL instrumentation can pass raw queries through the graphql.document attribute. Queries might contain sensitive information.	false	Experimental
OTEL_DOTNET_AUTO_ORACLEMDA_SET_DBSTATEMENT_FOR_TEXT	Whether the Oracle Client instrumentation can pass SQL statements through the db.statement attribute. Queries might contain sensitive information. If set to false, db.statement is recorded only for executing stored procedures.	false	Experimental
OTEL_DOTNET_AUTO_SQLCLIENT_SET_DBSTATEMENT_FOR_TEXT	Whether the SQL Client instrumentation can pass SQL statements through the db.statement attribute. Queries might contain sensitive information. If set to false, db.statement is recorded only for executing stored procedures. Not supported on .NET Framework for System.Data.SqlClient.	false	Experimental
OTEL_DOTNET_AUTO_TRACES_ASPNET_INSTRUMENTATION_CAPTURE_REQUEST_HEADERS	A comma-separated list of HTTP header names. ASP.NET instrumentations will capture HTTP request header values for all configured header names.		Experimental
OTEL_DOTNET_AUTO_TRACES_ASPNET_INSTRUMENTATION_CAPTURE_RESPONSE_HEADERS	A comma-separated list of HTTP header names. ASP.NET instrumentations will capture HTTP response header values for all configured header names. Not supported on IIS Classic mode.		Experimental
OTEL_DOTNET_AUTO_TRACES_ASPNETCORE_INSTRUMENTATION_CAPTURE_REQUEST_HEADERS	A comma-separated list of HTTP header names. ASP.NET Core instrumentations will capture HTTP request header values for all configured header names.		Experimental
OTEL_DOTNET_AUTO_TRACES_ASPNETCORE_INSTRUMENTATION_CAPTURE_RESPONSE_HEADERS	A comma-separated list of HTTP header names. ASP.NET Core instrumentations will capture HTTP response header values for all configured header names.		Experimental
OTEL_DOTNET_AUTO_TRACES_GRPCNETCLIENT_INSTRUMENTATION_CAPTURE_REQUEST_METADATA	A comma-separated list of gRPC metadata names. Grpc.Net.Client instrumentations will capture gRPC request metadata values for all configured metadata names.		Experimental
OTEL_DOTNET_AUTO_TRACES_GRPCNETCLIENT_INSTRUMENTATION_CAPTURE_RESPONSE_METADATA	A comma-separated list of gRPC metadata names. Grpc.Net.Client instrumentations will capture gRPC response metadata values for all configured metadata names.		Experimental
OTEL_DOTNET_AUTO_TRACES_HTTP_INSTRUMENTATION_CAPTURE_REQUEST_HEADERS	A comma-separated list of HTTP header names. HTTP Client instrumentations will capture HTTP request header values for all configured header names.		Experimental
OTEL_DOTNET_AUTO_TRACES_HTTP_INSTRUMENTATION_CAPTURE_RESPONSE_HEADERS	A comma-separated list of HTTP header names. HTTP Client instrumentations will capture HTTP response header values for all configured header names.		Experimental
OTEL_DOTNET_EXPERIMENTAL_ASPNETCORE_DISABLE_URL_QUERY_REDACTION	Whether the ASP.NET Core instrumentation turns off redaction of the url.query attribute value.	false	Experimental
OTEL_DOTNET_EXPERIMENTAL_HTTPCLIENT_DISABLE_URL_QUERY_REDACTION	Whether the HTTP client instrumentation turns off redaction of the url.full attribute value.	false	Experimental
OTEL_DOTNET_EXPERIMENTAL_ASPNET_DISABLE_URL_QUERY_REDACTION	Whether the ASP.NET instrumentation turns off redaction of the url.query attribute value.	false	Experimental

Propagators

Propagators allow applications to share context. See the OpenTelemetry specification for more details.

Environment variable	Description	Default value
OTEL_PROPAGATORS	Comma-separated list of propagators. Supported options: tracecontext, baggage, b3multi, b3. See the OpenTelemetry specification for more details.	tracecontext,baggage

Samplers

Samplers let you control potential noise and overhead introduced by OpenTelemetry instrumentation by selecting which traces you want to collect and export. See the OpenTelemetry specification for more details.

Environment variable	Description	Default value	Status
OTEL_TRACES_SAMPLER	Sampler to be used for traces [1]	parentbased_always_on	Stable
OTEL_TRACES_SAMPLER_ARG	String value to be used as the sampler argument [2]		Stable

[1]: Supported values are:

• always_on,
• always_off,
• traceidratio,
• parentbased_always_on,
• parentbased_always_off,
• parentbased_traceidratio.

[2]: For traceidratio and parentbased_traceidratio samplers: Sampling probability, a number in the [0..1] range, e.g. "0.25". Default is 1.0.

Exporters

Exporters output the telemetry.

Environment variable	Description	Default value	Status
OTEL_TRACES_EXPORTER	Comma-separated list of propagators. Supported options: otlp, zipkin, console, none. See the OpenTelemetry specification for more details.	otlp	Stable
OTEL_METRICS_EXPORTER	Comma-separated list of propagators. Supported options: otlp, prometheus, console, none. See the OpenTelemetry specification for more details.	otlp	Stable
OTEL_LOGS_EXPORTER	Comma-separated list of propagators. Supported options: otlp, console, none. See the OpenTelemetry specification for more details.	otlp	Stable

Traces exporter

Environment variable	Description	Default value	Status
OTEL_BSP_SCHEDULE_DELAY	Delay interval (in milliseconds) between two consecutive exports.	5000	Stable
OTEL_BSP_EXPORT_TIMEOUT	Maximum allowed time (in milliseconds) to export data	30000	Stable
OTEL_BSP_MAX_QUEUE_SIZE	Maximum queue size.	2048	Stable
OTEL_BSP_MAX_EXPORT_BATCH_SIZE	Maximum batch size. Must be less than or equal to OTEL_BSP_MAX_QUEUE_SIZE.	512	Stable

Metrics exporter

Environment variable	Description	Default value	Status
OTEL_METRIC_EXPORT_INTERVAL	The time interval (in milliseconds) between the start of two export attempts.	60000 for OTLP exporter, 10000 for console exporter	Stable
OTEL_METRIC_EXPORT_TIMEOUT	Maximum allowed time (in milliseconds) to export data.	30000 for OTLP exporter, none for console exporter	Stable

Logs exporter

Environment variable	Description	Default value	Status
OTEL_DOTNET_AUTO_LOGS_INCLUDE_FORMATTED_MESSAGE	Whether the formatted log message should be set or not.	false	Experimental

OTLP

Status: Stable

To enable the OTLP exporter, set the OTEL_TRACES_EXPORTER/OTEL_METRICS_EXPORTER/OTEL_LOGS_EXPORTER environment variable to otlp.

To customize the OTLP exporter using environment variables, see the OTLP exporter documentation. Important environment variables include:

Environment variable	Description	Default value	Status
OTEL_EXPORTER_OTLP_ENDPOINT	Target endpoint for the OTLP exporter. See the OpenTelemetry specification for more details.	http/protobuf: http://localhost:4318, grpc: http://localhost:4317	Stable
OTEL_EXPORTER_OTLP_TRACES_ENDPOINT	Equivalent to OTEL_EXPORTER_OTLP_ENDPOINT, but applies only to traces.	http/protobuf: http://localhost:4318/v1/traces, grpc: http://localhost:4317	Stable
OTEL_EXPORTER_OTLP_METRICS_ENDPOINT	Equivalent to OTEL_EXPORTER_OTLP_ENDPOINT, but applies only to metrics.	http/protobuf: http://localhost:4318/v1/metrics, grpc: http://localhost:4317	Stable
OTEL_EXPORTER_OTLP_LOGS_ENDPOINT	Equivalent to OTEL_EXPORTER_OTLP_ENDPOINT, but applies only to logs.	http/protobuf: http://localhost:4318/v1/logs, grpc: http://localhost:4317	Stable
OTEL_EXPORTER_OTLP_PROTOCOL	OTLP exporter transport protocol. Supported values are grpc, http/protobuf. [1]	http/protobuf	Stable
OTEL_EXPORTER_OTLP_TRACES_PROTOCOL	Equivalent to OTEL_EXPORTER_OTLP_PROTOCOL, but applies only to traces.	http/protobuf	Stable
OTEL_EXPORTER_OTLP_METRICS_PROTOCOL	Equivalent to OTEL_EXPORTER_OTLP_PROTOCOL, but applies only to metrics.	http/protobuf	Stable
OTEL_EXPORTER_OTLP_LOGS_PROTOCOL	Equivalent to OTEL_EXPORTER_OTLP_PROTOCOL, but applies only to logs.	http/protobuf	Stable
OTEL_EXPORTER_OTLP_TIMEOUT	The max waiting time (in milliseconds) for the backend to process each batch.	10000 (10s)	Stable
OTEL_EXPORTER_OTLP_TRACES_TIMEOUT	Equivalent to OTEL_EXPORTER_OTLP_TIMEOUT, but applies only to traces.	10000 (10s)	Stable
OTEL_EXPORTER_OTLP_METRICS_TIMEOUT	Equivalent to OTEL_EXPORTER_OTLP_TIMEOUT, but applies only to metrics.	10000 (10s)	Stable
OTEL_EXPORTER_OTLP_LOGS_TIMEOUT	Equivalent to OTEL_EXPORTER_OTLP_TIMEOUT, but applies only to logs.	10000 (10s)	Stable
OTEL_EXPORTER_OTLP_HEADERS	Comma-separated list of additional HTTP headers sent with each export, for example: Authorization=secret,X-Key=Value.		Stable
OTEL_EXPORTER_OTLP_TRACES_HEADERS	Equivalent to OTEL_EXPORTER_OTLP_HEADERS, but applies only to traces.		Stable
OTEL_EXPORTER_OTLP_METRICS_HEADERS	Equivalent to OTEL_EXPORTER_OTLP_HEADERS, but applies only to metrics.		Stable
OTEL_EXPORTER_OTLP_LOGS_HEADERS	Equivalent to OTEL_EXPORTER_OTLP_HEADERS, but applies only to logs.		Stable
OTEL_ATTRIBUTE_VALUE_LENGTH_LIMIT	Maximum allowed attribute value size.	none	Stable
OTEL_ATTRIBUTE_COUNT_LIMIT	Maximum allowed span attribute count.	128	Stable
OTEL_SPAN_ATTRIBUTE_VALUE_LENGTH_LIMIT	Maximum allowed attribute value size. Not applicable for metrics..	none	Stable
OTEL_SPAN_ATTRIBUTE_COUNT_LIMIT	Maximum allowed span attribute count. Not applicable for metrics..	128	Stable
OTEL_SPAN_EVENT_COUNT_LIMIT	Maximum allowed span event count.	128	Stable
OTEL_SPAN_LINK_COUNT_LIMIT	Maximum allowed span link count.	128	Stable
OTEL_EVENT_ATTRIBUTE_COUNT_LIMIT	Maximum allowed attribute per span event count.	128	Stable
OTEL_LINK_ATTRIBUTE_COUNT_LIMIT	Maximum allowed attribute per span link count.	128	Stable
OTEL_EXPORTER_OTLP_METRICS_TEMPORALITY_PREFERENCE	The aggregation temporality to use on the basis of instrument kind. [2]	cumulative	Stable

[1]: Considerations on the OTEL_EXPORTER_OTLP_PROTOCOL:

• The OpenTelemetry .NET Automatic Instrumentation defaults to http/protobuf, which differs from the OpenTelemetry .NET SDK default value of grpc.
• On .NET 6 and higher, the application must reference Grpc.Net.Client to use the grpc OTLP exporter protocol. For example, by adding <PackageReference Include="Grpc.Net.Client" Version="2.65.0" /> to the .csproj file.
• On .NET Framework, the grpc OTLP exporter protocol is not supported.

[2]: The recognized (case-insensitive) values for OTEL_EXPORTER_OTLP_METRICS_TEMPORALITY_PREFERENCE are:

• Cumulative: Choose cumulative aggregation temporality for all instrument kinds.
• Delta: Choose Delta aggregation temporality for Counter, Asynchronous Counter and Histogram instrument kinds, choose Cumulative aggregation for UpDownCounter and Asynchronous UpDownCounter instrument kinds.
• LowMemory: This configuration uses Delta aggregation temporality for Synchronous Counter and Histogram and uses Cumulative aggregation temporality for Synchronous UpDownCounter, Asynchronous Counter, and Asynchronous UpDownCounter instrument kinds.
  • ⚠️ This value known from specification is not supported.

Prometheus

Status: Experimental

Warning

Do NOT use in production.

Prometheus exporter is intended for the inner dev loop. Production environments can use a combination of OTLP exporter with OpenTelemetry Collector having otlp receiver and prometheus exporter.

To enable the Prometheus exporter, set the OTEL_METRICS_EXPORTER environment variable to prometheus.

The exporter exposes the metrics HTTP endpoint on http://localhost:9464/metrics and it caches the responses for 300 milliseconds.

See the Prometheus Exporter HttpListener documentation. to learn more.

Zipkin

Status: Stable

To enable the Zipkin exporter, set the OTEL_TRACES_EXPORTER environment variable to zipkin.

To customize the Zipkin exporter using environment variables, see the Zipkin exporter documentation. Important environment variables include:

Environment variable	Description	Default value	Status
OTEL_EXPORTER_ZIPKIN_ENDPOINT	Zipkin URL	http://localhost:9411/api/v2/spans	Stable

Additional settings

Environment variable	Description	Default value	Status
OTEL_DOTNET_AUTO_TRACES_ENABLED	Enables traces.	true	Experimental
OTEL_DOTNET_AUTO_OPENTRACING_ENABLED	Enables OpenTracing tracer.	false	Experimental
OTEL_DOTNET_AUTO_LOGS_ENABLED	Enables logs.	true	Experimental
OTEL_DOTNET_AUTO_METRICS_ENABLED	Enables metrics.	true	Experimental
OTEL_DOTNET_AUTO_NETFX_REDIRECT_ENABLED	Enables automatic redirection of the assemblies used by the automatic instrumentation on the .NET Framework.	true	Experimental
OTEL_DOTNET_AUTO_TRACES_ADDITIONAL_SOURCES	Comma-separated list of additional System.Diagnostics.ActivitySource names to be added to the tracer at the startup. Use it to capture manually instrumented spans.		Experimental
OTEL_DOTNET_AUTO_TRACES_ADDITIONAL_LEGACY_SOURCES	Comma-separated list of additional legacy source names to be added to the tracer at the startup. Use it to capture System.Diagnostics.Activity objects created without using the System.Diagnostics.ActivitySource API.		Experimental
OTEL_DOTNET_AUTO_FLUSH_ON_UNHANDLEDEXCEPTION	Controls whether the telemetry data is flushed when an AppDomain.UnhandledException event is raised. Set to true when you suspect that you are experiencing a problem with missing telemetry data and also experiencing unhandled exceptions.	false	Experimental
OTEL_DOTNET_AUTO_METRICS_ADDITIONAL_SOURCES	Comma-separated list of additional System.Diagnostics.Metrics.Meter names to be added to the meter at the startup. Use it to capture manually created metrics.		Experimental
OTEL_DOTNET_AUTO_PLUGINS	Colon-separated list of OTel SDK instrumentation plugin types, specified with the assembly-qualified name. Note: This list must be colon-separated because the type names may include commas. See more info on how to write plugins at plugins.md.		Experimental

RuleEngine

RuleEngine is a feature that validates OpenTelemetry API, SDK, Instrumentation, and Exporter assemblies for unsupported scenarios, ensuring that OpenTelemetry automatic instrumentation is more stable by backing of instead of crashing. It works on .NET 6 and higher.

Enable RuleEngine only during the first run of the application, or when the deployment changes or the Automatic Instrumentation library is upgraded. Once validated, there's no need to revalidate the rules when the application restarts.

Environment variable	Description	Default value	Status
OTEL_DOTNET_AUTO_RULE_ENGINE_ENABLED	Enables RuleEngine.	true	Experimental

.NET CLR Profiler

The CLR uses the following environment variables to set up the profiler. See .NET Runtime Profiler Loading for more information.

.NET Framework environment variable	.NET environment variable	Description	Required value	Status
COR_ENABLE_PROFILING	CORECLR_ENABLE_PROFILING	Enables the profiler.	1	Experimental
COR_PROFILER	CORECLR_PROFILER	CLSID of the profiler.	{918728DD-259F-4A6A-AC2B-B85E1B658318}	Experimental
COR_PROFILER_PATH	CORECLR_PROFILER_PATH	Path to the profiler.	$INSTALL_DIR/linux-x64/OpenTelemetry.AutoInstrumentation.Native.so for Linux glibc, $INSTALL_DIR/linux-musl-x64/OpenTelemetry.AutoInstrumentation.Native.so for Linux musl, $INSTALL_DIR/osx-x64/OpenTelemetry.AutoInstrumentation.Native.dylib for macOS	Experimental
COR_PROFILER_PATH_32	CORECLR_PROFILER_PATH_32	Path to the 32-bit profiler. Bitness-specific paths take precedence over generic paths.	$INSTALL_DIR/win-x86/OpenTelemetry.AutoInstrumentation.Native.dll for Windows	Experimental
COR_PROFILER_PATH_64	CORECLR_PROFILER_PATH_64	Path to the 64-bit profiler. Bitness-specific paths take precedence over generic paths.	$INSTALL_DIR/win-x64/OpenTelemetry.AutoInstrumentation.Native.dll for Windows	Experimental

Setting OpenTelemetry .NET Automatic Instrumentation as a .NET CLR Profiler is required for .NET Framework.

On .NET, the .NET CLR Profiler is used only for bytecode instrumentation. If having just source instrumentation is acceptable, you can unset or remove the following environment variables:

COR_ENABLE_PROFILING
COR_PROFILER
COR_PROFILER_PATH_32
COR_PROFILER_PATH_64
CORECLR_ENABLE_PROFILING
CORECLR_PROFILER
CORECLR_PROFILER_PATH
CORECLR_PROFILER_PATH_32
CORECLR_PROFILER_PATH_64

.NET Runtime

On .NET it is required to set the DOTNET_STARTUP_HOOKS environment variable.

The DOTNET_ADDITIONAL_DEPS and DOTNET_SHARED_STORE environment variable are used to mitigate assembly version conflicts in .NET.

Environment variable	Required value	Status
DOTNET_STARTUP_HOOKS	$INSTALL_DIR/net/OpenTelemetry.AutoInstrumentation.StartupHook.dll	Experimental
DOTNET_ADDITIONAL_DEPS	$INSTALL_DIR/AdditionalDeps	Experimental
DOTNET_SHARED_STORE	$INSTALL_DIR/store	Experimental

Internal logs

The default directory paths for internal logs are:

• Windows: %ProgramData%\OpenTelemetry .NET AutoInstrumentation\logs
• Linux: /var/log/opentelemetry/dotnet
• macOS: /var/log/opentelemetry/dotnet

If the default log directories can't be created, the instrumentation uses the path of the current user's temporary folder instead.

Environment variable	Description	Default value	Status
OTEL_DOTNET_AUTO_LOG_DIRECTORY	Directory of the .NET Tracer logs.	See the previous note on default paths	Experimental
OTEL_LOG_LEVEL	SDK log level. (supported values: none,error,warn,info,debug)	info	Stable
OTEL_DOTNET_AUTO_TRACES_CONSOLE_EXPORTER_ENABLED	Whether the traces console exporter is enabled or not.	false	Deprecated
OTEL_DOTNET_AUTO_METRICS_CONSOLE_EXPORTER_ENABLED	Whether the metrics console exporter is enabled or not.	false	Deprecated
OTEL_DOTNET_AUTO_LOGS_CONSOLE_EXPORTER_ENABLED	Whether the logs console exporter is enabled or not.	false	Deprecated
OTEL_DOTNET_AUTO_LOGS_INCLUDE_FORMATTED_MESSAGE	Whether the log state should be formatted.	false	Experimental