# OTLP Exporter for OpenTelemetry .NET
[](https://www.nuget.org/packages/OpenTelemetry.Exporter.OpenTelemetryProtocol)
[](https://www.nuget.org/packages/OpenTelemetry.Exporter.OpenTelemetryProtocol)
[The OTLP (OpenTelemetry Protocol) exporter](https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/protocol/exporter.md)
implementation.
<details>
<summary>Table of Contents</summary>
* [Installation](#installation)
* [Enable Log Exporter](#enable-log-exporter)
* [Enable Metric Exporter](#enable-metric-exporter)
* [Enable Trace Exporter](#enable-trace-exporter)
* [Enable OTLP Exporter for all signals](#enable-otlp-exporter-for-all-signals)
* [Configuration](#configuration)
* [OtlpExporterOptions](#otlpexporteroptions)
* [LogRecordExportProcessorOptions](#logrecordexportprocessoroptions)
* [MetricReaderOptions](#metricreaderoptions)
* [Environment Variables](#environment-variables)
* [Exporter configuration](#exporter-configuration)
* [Attribute limits](#attribute-limits)
* [Configure HttpClient](#configure-httpclient)
* [Experimental features](#experimental-features)
* [Troubleshooting](#troubleshooting)
</details>
## Prerequisite
* An endpoint capable of accepting OTLP, like [OpenTelemetry
Collector](https://opentelemetry.io/docs/collector/) or similar.
## Installation
```shell
dotnet add package OpenTelemetry.Exporter.OpenTelemetryProtocol
```
## Enable Log Exporter
```csharp
var loggerFactory = LoggerFactory.Create(builder =>
{
builder.AddOpenTelemetry(options =>
{
options.AddOtlpExporter();
});
});
```
By default, `AddOtlpExporter()` pairs the OTLP Log Exporter with a [batching
processor](https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/logs/sdk.md#batching-processor).
See [`TestLogs.cs`](../../examples/Console/TestLogs.cs) for example on how to
customize the `LogRecordExportProcessorOptions` or see the [Environment
Variables](#environment-variables) section below on how to customize using
environment variables.
> [!NOTE]
> For details on how to configure logging with OpenTelemetry check the
[Console](../../docs/logs/getting-started-console/README.md) or [ASP.NET
Core](../../docs/logs/getting-started-aspnetcore/README.md) tutorial.
**ILogger Scopes**: OTLP Log Exporter supports exporting `ILogger` scopes as
Attributes. Scopes must be enabled at the SDK level using
[IncludeScopes](../../docs/logs/customizing-the-sdk/Readme.md#includescopes)
setting on `OpenTelemetryLoggerOptions`.
> [!NOTE]
> Scope attributes with key set as empty string or `{OriginalFormat}`
are ignored by exporter. Duplicate keys are exported as is.
## Enable Metric Exporter
This exporter provides `AddOtlpExporter()` extension method on `MeterProviderBuilder`
to enable exporting of metrics. The following snippet adds the Exporter with default
[configuration](#configuration).
```csharp
var meterProvider = Sdk.CreateMeterProviderBuilder()
// rest of config not shown here.
.AddOtlpExporter()
.Build();
```
By default, `AddOtlpExporter()` pairs the OTLP MetricExporter with a
[PeriodicExportingMetricReader](https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/metrics/sdk.md#periodic-exporting-metricreader)
with metric export interval of 60 secs and
[Temporality](https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/metrics/data-model.md#temporality)
set as `Cumulative`. See
[`TestMetrics.cs`](../../examples/Console/TestMetrics.cs) for example on how to
customize the `MetricReaderOptions` or see the [Environment
Variables](#environment-variables) section below on how to customize using
environment variables.
## Enable Trace Exporter
This exporter provides `AddOtlpExporter()` extension method on `TracerProviderBuilder`
to enable exporting of traces. The following snippet adds the Exporter with default
[configuration](#configuration).
```csharp
var tracerProvider = Sdk.CreateTracerProviderBuilder()
// rest of config not shown here.
.AddOtlpExporter()
.Build();
```
See the [`TestOtlpExporter.cs`](../../examples/Console/TestOtlpExporter.cs) for
runnable example.
## Enable OTLP Exporter for all signals
Starting with the `1.8.0-beta.1` version you can use the cross-cutting
`UseOtlpExporter` extension to simplify registration of the OTLP exporter for
all signals (logs, metrics, and traces).
> [!NOTE]
> The cross cutting extension is currently only available when using the
`AddOpenTelemetry` extension in the
[OpenTelemetry.Extensions.Hosting](../OpenTelemetry.Extensions.Hosting/README.md)
package.
```csharp
appBuilder.Services.AddOpenTelemetry()
.UseOtlpExporter();
```
The `UseOtlpExporter` has the following behaviors:
* Calling `UseOtlpExporter` automatically enables logging, metrics, and tracing
however only telemetry which has been enabled will be exported.
There are different mechanisms available to enable telemetry:
* Logging
`ILogger` telemetry is controlled by category filters typically set through
configuration. For details see: [Log
Filtering](../../docs/logs/customizing-the-sdk/README.md#log-filtering) and
[Logging in
.NET](https://docs.microsoft.com/dotnet/core/extensions/logging).
* Metrics
Metrics telemetry is controlled by calling `MeterProviderBuilder.AddMeter`
to listen to
[Meter](https://learn.microsoft.com/dotnet/api/system.diagnostics.meter)s
emitting metrics. Typically instrumentation packages will make this call
automatically.
Examples:
```csharp
appBuilder.Services.AddOpenTelemetry()
.UseOtlpExporter()
.WithMetrics(metrics => metrics
.AddMeter(MyMeter.Name) // Listen to custom telemetry
.AddAspNetCoreInstrumentation() // Use instrumentation to listen to telemetry
);
```
```csharp
appBuilder.Services.ConfigureOpenTelemetryMeterProvider(metrics => metrics
.AddMeter(MyMeter.Name) // Listen to custom telemetry
.AddAspNetCoreInstrumentation() // Use instrumentation to listen to telemetry
);
appBuilder.Services.AddOpenTelemetry()
.UseOtlpExporter();
```
For details see: [Meter](../../docs/metrics/customizing-the-sdk/README.md#meter).
When using `Microsoft.Extensions.Hosting` v8.0.0 or greater (a standard part
of ASP.NET Core) `Meter`s and `Instrument`s can also be enabled using
configuration.
`appSettings.json` metrics configuration example:
```json
{
"Metrics": {
"EnabledMetrics": {
"Microsoft.AspNetCore.*": true,
"System.*": true,
"MyCompany.*": true,
}
}
}
```
For details about the built-in metrics exposed by .NET see: [Built-in
metrics in
.NET](https://learn.microsoft.com/dotnet/core/diagnostics/built-in-metrics).
* Tracing
Trace telemetry is controlled by calling `TracerProviderBuilder.AddSource`
to listen to
[ActivitySource](https://learn.microsoft.com/dotnet/api/system.diagnostics.activitysource)s
emitting traces. Typically instrumentation packages will make this call
automatically.
Examples:
```csharp
appBuilder.Services.AddOpenTelemetry()
.UseOtlpExporter()
.WithTracing(tracing => tracing
.AddSource(MyActivitySource.Name) // Listen to custom telemetry
.AddAspNetCoreInstrumentation() // Use instrumentation to listen to telemetry
);
```
```csharp
appBuilder.Services.ConfigureOpenTelemetryTracerProvider(tracing => tracing
.AddSource(MyActivitySource.Name) // Listen to custom telemetry
.AddAspNetCoreInstrumentation() // Use instrumentation to listen to telemetry
);
appBuilder.Services.AddOpenTelemetry()
.UseOtlpExporter();
```
For details see: [Activity Source](../../docs/trace/customizing-the-sdk/README.md#activity-source).
* The exporter registered by `UseOtlpExporter` will be added as the last
processor in the pipeline established for logging and tracing.
* `UseOtlpExporter` can only be called once. Subsequent calls will result in a
`NotSupportedException` being thrown.
* `UseOtlpExporter` cannot be called in addition to signal-specific
`AddOtlpExporter` methods. If `UseOtlpExporter` is called signal-specific
`AddOtlpExporter` calls will result in a `NotSupportedException` being thrown.
### Configuring signals when using UseOtlpExporter
`UseOtlpExporter` supports the full set of [environment
variables](#environment-variables) listed below including the signal-specific
overrides and users are encouraged to use this mechanism to configure their
exporters.
A `UseOtlpExporter` overload is provided which may be used to set the protocol
and base URL:
```csharp
appBuilder.Services.AddOpenTelemetry()
.UseOtlpExporter(OtlpExportProtocol.HttpProtobuf, new Uri("http://localhost:4318/"));
```
> [!NOTE]
> When the protocol is set to `OtlpExportProtocol.HttpProtobuf` a
signal-specific path will be appended automatically to the base URL when
constructing exporters.
## Configuration
You can configure the `OtlpExporter` through `OtlpExporterOptions`
and environment variables.
> [!NOTE]
> The `OtlpExporterOptions` type setters take precedence over the environment variables.
This can be achieved by providing an `Action<OtlpExporterOptions>` delegate to
the `AddOtlpExporter()` method or using the `Configure<OtlpExporterOptions>()`
Options API extension:
```csharp
// Set via delegate using code:
appBuilder.Services.AddOpenTelemetry()
.WithTracing(builder => builder.AddOtlpExporter(o => {
// ...
}));
// Set via Options API using code:
appBuilder.Services.Configure<OtlpExporterOptions>(o => {
// ...
});
// Set via Options API using configuration:
appBuilder.Services.Configure<OtlpExporterOptions>(
appBuilder.Configuration.GetSection("OpenTelemetry:otlp"));
```
If additional services from the dependency injection are required for
configuration they can be accessed through the Options API like this:
```csharp
// Step 1: Register user-created configuration service.
appBuilder.Services.AddSingleton<MyOtlpConfigurationService>();
// Step 2: Use Options API to configure OtlpExporterOptions with user-created service.
appBuilder.Services.AddOptions<OtlpExporterOptions>()
.Configure<MyOtlpConfigurationService>((o, configService) => {
o.Endpoint = configService.ResolveOtlpExporterEndpoint();
});
```
> [!NOTE]
> The `OtlpExporterOptions` class is shared by logging, metrics, and tracing. To
> bind configuration specific to each signal use the `name` parameter on the
> `AddOtlpExporter` extensions:
>
> ```csharp
> // Step 1: Bind options to config using the name parameter.
> appBuilder.Services.Configure<OtlpExporterOptions>("tracing", appBuilder.Configuration.GetSection("OpenTelemetry:tracing:otlp"));
> appBuilder.Services.Configure<OtlpExporterOptions>("metrics", appBuilder.Configuration.GetSection("OpenTelemetry:metrics:otlp"));
> appBuilder.Services.Configure<OtlpExporterOptions>("logging", appBuilder.Configuration.GetSection("OpenTelemetry:logging:otlp"));
>
> // Step 2: Register OtlpExporter using the name parameter.
> appBuilder.Services.AddOpenTelemetry()
> .WithTracing(builder => builder.AddOtlpExporter("tracing", configure: null))
> .WithMetrics(builder => builder.AddOtlpExporter("metrics", configure: null));
>
> appBuilder.Logging.AddOpenTelemetry(builder => builder.AddOtlpExporter(
> "logging",
> options =>
> {
> // Note: Options can also be set via code but order is important. In the example here the code will apply after configuration.
> options.Endpoint = new Uri("http://localhost/logs");
> }));
> ```
### OtlpExporterOptions
* `Protocol`: OTLP transport protocol. Supported values:
`OtlpExportProtocol.Grpc` and `OtlpExportProtocol.HttpProtobuf`.
The default is `OtlpExportProtocol.Grpc`.
* `Endpoint`: Target to which the exporter is going to send traces or metrics.
The endpoint must be a valid Uri with scheme (http or https) and host, and MAY
contain a port and path. The default is "localhost:4317" for
`OtlpExportProtocol.Grpc` and "localhost:4318" for
`OtlpExportProtocol.HttpProtobuf`.
> [!NOTE]
> When using `OtlpExportProtocol.HttpProtobuf`, the full URL MUST be
> provided, including the signal-specific path v1/{signal}. For example, for
> traces, the full URL will look like `http://your-custom-endpoint/v1/traces`.
* `Headers`: Optional headers for the connection.
* `HttpClientFactory`: A factory function called to create the `HttpClient`
instance that will be used at runtime to transmit telemetry over HTTP when the
`HttpProtobuf` protocol is configured. See [Configure
HttpClient](#configure-httpclient) for more details.
* `TimeoutMilliseconds` : Max waiting time for the backend to process a batch.
The following options are only applicable to `OtlpTraceExporter`:
* `ExportProcessorType`: Whether the exporter should use [Batch or Simple
exporting
processor](https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/trace/sdk.md#built-in-span-processors).
The default is Batch.
* `BatchExportProcessorOptions`: Configuration options for the batch exporter.
Only used if ExportProcessorType is set to Batch.
See the [`TestOtlpExporter.cs`](../../examples/Console/TestOtlpExporter.cs) for
an example of how to use the exporter.
### LogRecordExportProcessorOptions
The `LogRecordExportProcessorOptions` class may be used to configure processor &
batch settings for logging:
```csharp
// Set via delegate using code:
appBuilder.Logging.AddOpenTelemetry(options =>
{
options.AddOtlpExporter((exporterOptions, processorOptions) =>
{
processorOptions.BatchExportProcessorOptions.ScheduledDelayMilliseconds = 2000;
processorOptions.BatchExportProcessorOptions.MaxExportBatchSize = 5000;
});
});
// Set via Options API using code:
appBuilder.Services.Configure<LogRecordExportProcessorOptions>(o =>
{
o.BatchExportProcessorOptions.ScheduledDelayMilliseconds = 2000;
o.BatchExportProcessorOptions.MaxExportBatchSize = 5000;
});
// Set via Options API using configuration:
appBuilder.Services.Configure<LogRecordExportProcessorOptions>(
appBuilder.Configuration.GetSection("OpenTelemetry:Logging"));
```
### MetricReaderOptions
The `MetricReaderOptions` class may be used to configure reader settings for
metrics:
```csharp
// Set via delegate using code:
appBuilder.Services.AddOpenTelemetry()
.WithMetrics(builder => builder.AddOtlpExporter((exporterOptions, readerOptions) =>
{
readerOptions.PeriodicExportingMetricReaderOptions.ExportIntervalMilliseconds = 10_000;
}));
// Set via Options API using code:
appBuilder.Services.Configure<MetricReaderOptions>(o =>
{
o.PeriodicExportingMetricReaderOptions.ExportIntervalMilliseconds = 10_000;
});
// Set via Options API using configuration:
appBuilder.Services.Configure<MetricReaderOptions>(
appBuilder.Configuration.GetSection("OpenTelemetry:Metrics"));
```
## Environment Variables
The following environment variables can be used to configure the OTLP Exporter
for logs, traces, and metrics.
> [!NOTE]
> In OpenTelemetry .NET environment variable keys are retrieved using
`IConfiguration` which means they may be set using other mechanisms such as
defined in `appSettings.json` or specified on the command-line.
### Exporter configuration
The [OpenTelemetry
Specification](https://github.com/open-telemetry/opentelemetry-specification/)
defines environment variables which can be used to configure the [OTLP
exporter](https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/protocol/exporter.md)
and its associated processor
([logs](https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/configuration/sdk-environment-variables.md#batch-logrecord-processor)
&
[traces](https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/configuration/sdk-environment-variables.md#batch-span-processor))
or reader
([metrics](https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/configuration/sdk-environment-variables.md#periodic-exporting-metricreader)).
* All signals
The following environment variables can be used to override the default
values of the `OtlpExporterOptions`:
| Environment variable | `OtlpExporterOptions` property |
| ------------------------------| --------------------------------------|
| `OTEL_EXPORTER_OTLP_ENDPOINT` | `Endpoint` |
| `OTEL_EXPORTER_OTLP_HEADERS` | `Headers` |
| `OTEL_EXPORTER_OTLP_TIMEOUT` | `TimeoutMilliseconds` |
| `OTEL_EXPORTER_OTLP_PROTOCOL` | `Protocol` (`grpc` or `http/protobuf`)|
* Logs:
The following environment variables can be used to override the default values
for the batch processor configured for logging:
| Environment variable | `BatchExportLogRecordProcessorOptions` property |
| ----------------------------------| ------------------------------------------------------------------------|
| `OTEL_BLRP_SCHEDULE_DELAY` | `ScheduledDelayMilliseconds` |
| `OTEL_BLRP_EXPORT_TIMEOUT` | `ExporterTimeoutMilliseconds` |
| `OTEL_BLRP_MAX_QUEUE_SIZE` | `MaxQueueSize` |
| `OTEL_BLRP_MAX_EXPORT_BATCH_SIZE` | `MaxExportBatchSize` |
The following environment variables can be used to override the default values
of the `OtlpExporterOptions` used for logging when using the [UseOtlpExporter
extension](#enable-otlp-exporter-for-all-signals):
| Environment variable | `OtlpExporterOptions` property | UseOtlpExporter | AddOtlpExporter |
| --------------------------------------| --------------------------------------|-----------------|-----------------|
| `OTEL_EXPORTER_OTLP_LOGS_ENDPOINT` | `Endpoint` | Supported | Not supported |
| `OTEL_EXPORTER_OTLP_LOGS_HEADERS` | `Headers` | Supported | Not supported |
| `OTEL_EXPORTER_OTLP_LOGS_TIMEOUT` | `TimeoutMilliseconds` | Supported | Not supported |
| `OTEL_EXPORTER_OTLP_LOGS_PROTOCOL` | `Protocol` (`grpc` or `http/protobuf`)| Supported | Not supported |
* Metrics:
The following environment variables can be used to override the default value
of the `TemporalityPreference` setting for the reader configured for metrics
when using OTLP exporter:
| Environment variable | `MetricReaderOptions` property |
| ----------------------------------------------------| ------------------------------------------------|
| `OTEL_EXPORTER_OTLP_METRICS_TEMPORALITY_PREFERENCE` | `TemporalityPreference` |
The following environment variables can be used to override the default values
of the periodic exporting metric reader configured for metrics:
| Environment variable | `PeriodicExportingMetricReaderOptions` property |
| ----------------------------------------------------| ------------------------------------------------|
| `OTEL_METRIC_EXPORT_INTERVAL` | `ExportIntervalMilliseconds` |
| `OTEL_METRIC_EXPORT_TIMEOUT` | `ExportTimeoutMilliseconds` |
The following environment variables can be used to override the default values
of the `OtlpExporterOptions` used for metrics when using the [UseOtlpExporter
extension](#enable-otlp-exporter-for-all-signals):
| Environment variable | `OtlpExporterOptions` property | UseOtlpExporter | AddOtlpExporter |
| --------------------------------------| --------------------------------------|-----------------|-----------------|
| `OTEL_EXPORTER_OTLP_METRICS_ENDPOINT` | `Endpoint` | Supported | Not supported |
| `OTEL_EXPORTER_OTLP_METRICS_HEADERS` | `Headers` | Supported | Not supported |
| `OTEL_EXPORTER_OTLP_METRICS_TIMEOUT` | `TimeoutMilliseconds` | Supported | Not supported |
| `OTEL_EXPORTER_OTLP_METRICS_PROTOCOL` | `Protocol` (`grpc` or `http/protobuf`)| Supported | Not supported |
* Tracing:
The following environment variables can be used to override the default values
for the batch processor configured for tracing:
| Environment variable | `BatchExportActivityProcessorOptions` property |
| ---------------------------------| ------------------------------------------------------------|
| `OTEL_BSP_SCHEDULE_DELAY` | `ScheduledDelayMilliseconds` |
| `OTEL_BSP_EXPORT_TIMEOUT` | `ExporterTimeoutMilliseconds` |
| `OTEL_BSP_MAX_QUEUE_SIZE` | `MaxQueueSize` |
| `OTEL_BSP_MAX_EXPORT_BATCH_SIZE` | `MaxExportBatchSize` |
The following environment variables can be used to override the default values
of the `OtlpExporterOptions` used for tracing when using the [UseOtlpExporter
extension](#enable-otlp-exporter-for-all-signals):
| Environment variable | `OtlpExporterOptions` property | UseOtlpExporter | AddOtlpExporter |
| --------------------------------------| --------------------------------------|-----------------|-----------------|
| `OTEL_EXPORTER_OTLP_TRACES_ENDPOINT` | `Endpoint` | Supported | Not supported |
| `OTEL_EXPORTER_OTLP_TRACES_HEADERS` | `Headers` | Supported | Not supported |
| `OTEL_EXPORTER_OTLP_TRACES_TIMEOUT` | `TimeoutMilliseconds` | Supported | Not supported |
| `OTEL_EXPORTER_OTLP_TRACES_PROTOCOL` | `Protocol` (`grpc` or `http/protobuf`)| Supported | Not supported |
### Attribute limits
The [OpenTelemetry
Specification](https://github.com/open-telemetry/opentelemetry-specification/)
defines environment variables which can be used to configure [attribute
limits](https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/configuration/sdk-environment-variables.md#attribute-limits).
The following environment variables can be used to configure default attribute
limits:
* `OTEL_ATTRIBUTE_VALUE_LENGTH_LIMIT`
* `OTEL_ATTRIBUTE_COUNT_LIMIT`
The following environment variables can be used to configure span limits used
for tracing:
* `OTEL_SPAN_ATTRIBUTE_VALUE_LENGTH_LIMIT`
* `OTEL_SPAN_ATTRIBUTE_COUNT_LIMIT`
* `OTEL_SPAN_EVENT_COUNT_LIMIT`
* `OTEL_SPAN_LINK_COUNT_LIMIT`
* `OTEL_EVENT_ATTRIBUTE_COUNT_LIMIT`
* `OTEL_LINK_ATTRIBUTE_COUNT_LIMIT`
The following environment variables can be used to configure log record limits
used for logging:
* `OTEL_LOGRECORD_ATTRIBUTE_VALUE_LENGTH_LIMIT`
* `OTEL_LOGRECORD_ATTRIBUTE_COUNT_LIMIT`
## Configure HttpClient
The `HttpClientFactory` option is provided on `OtlpExporterOptions` for users
who want to configure the `HttpClient` used by the `OtlpTraceExporter`,
`OtlpMetricExporter`, and/or `OtlpLogExporter` when `HttpProtobuf` protocol is
used. Simply replace the function with your own implementation if you want to
customize the generated `HttpClient`:
> [!NOTE]
> The `HttpClient` instance returned by the `HttpClientFactory` function is used
for all export requests.
```csharp
services.AddOpenTelemetry()
.WithTracing(builder => builder
.AddOtlpExporter(o =>
{
o.Protocol = OtlpExportProtocol.HttpProtobuf;
o.HttpClientFactory = () =>
{
HttpClient client = new HttpClient();
client.DefaultRequestHeaders.Add("X-MyCustomHeader", "value");
return client;
};
}));
```
> [!NOTE]
> `DefaultRequestHeaders` can be used for [HTTP Basic Access
Authentication](https://en.wikipedia.org/wiki/Basic_access_authentication).
For more complex authentication requirements,
[`System.Net.Http.DelegatingHandler`](https://learn.microsoft.com/dotnet/api/system.net.http.delegatinghandler)
can be used to handle token refresh, as explained
[here](https://stackoverflow.com/questions/56204350/how-to-refresh-a-token-using-ihttpclientfactory).
For users using
[IHttpClientFactory](https://docs.microsoft.com/dotnet/architecture/microservices/implement-resilient-applications/use-httpclientfactory-to-implement-resilient-http-requests)
you may also customize the named "OtlpTraceExporter" and/or "OtlpMetricExporter"
`HttpClient` using the built-in `AddHttpClient` extension:
```csharp
services.AddHttpClient(
"OtlpTraceExporter",
configureClient: (client) =>
client.DefaultRequestHeaders.Add("X-MyCustomHeader", "value"));
```
> [!NOTE]
> `IHttpClientFactory` is NOT currently supported by `OtlpLogExporter`.
## Experimental features
The following features are exposed experimentally in the OTLP Exporter. Features
are exposed experimentally when either the [OpenTelemetry
Specification](https://github.com/open-telemetry/opentelemetry-specification)
has explicitly marked something
[experimental](https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/document-status.md)
or when the SIG members are still working through the design for a feature and
want to solicit feedback from the community.
### Environment variables
> [!NOTE]
> In OpenTelemetry .NET environment variable keys are retrieved using
`IConfiguration` which means they may be set using other mechanisms such as
defined in appSettings.json or specified on the command-line.
* All signals
* `OTEL_DOTNET_EXPERIMENTAL_OTLP_RETRY`
* When set to `in_memory`, it enables in-memory retry for transient errors
encountered while sending telemetry.
Added in `1.8.0`.
* When set to `disk`, it enables retries by storing telemetry on disk during
transient errors. The default path where the telemetry is stored is
obtained by calling
[Path.GetTempPath()](https://learn.microsoft.com/dotnet/api/system.io.path.gettemppath)
or can be customized by setting
`OTEL_DOTNET_EXPERIMENTAL_OTLP_DISK_RETRY_DIRECTORY_PATH` environment
variable.
The OTLP exporter utilizes a forked version of the
[OpenTelemetry.PersistentStorage.FileSystem](https://github.com/open-telemetry/opentelemetry-dotnet-contrib/tree/main/src/OpenTelemetry.PersistentStorage.FileSystem)
library to store telemetry data on disk. When a transient failure occurs,
a file is created at the specified directory path on disk containing the
serialized request data that was attempted to be sent to the OTLP
ingestion. A background thread attempts to resend any offline stored
telemetry every 60 seconds. For more details on how these files are
managed on disk, refer to the [File
details](https://github.com/open-telemetry/opentelemetry-dotnet-contrib/tree/main/src/OpenTelemetry.PersistentStorage.FileSystem#file-details).
Added in **TBD** (Unreleased).
* Logs
* `OTEL_DOTNET_EXPERIMENTAL_OTLP_EMIT_EVENT_LOG_ATTRIBUTES`
When set to `true`, it enables export of `LogRecord.EventId.Id` as
`logrecord.event.id` and `LogRecord.EventId.Name` as `logrecord.event.name`.
Added in `1.7.0-alpha.1`.
## Troubleshooting
This component uses an
[EventSource](https://docs.microsoft.com/dotnet/api/system.diagnostics.tracing.eventsource)
with the name "OpenTelemetry-Exporter-OpenTelemetryProtocol" for its internal
logging. Please refer to [SDK
troubleshooting](../OpenTelemetry/README.md#troubleshooting) for instructions on
seeing these internal logs.
## References
* [OpenTelemetry
Collector](https://github.com/open-telemetry/opentelemetry-collector)
* [OpenTelemetry Project](https://opentelemetry.io/)
* [OTLP proto files](https://github.com/open-telemetry/opentelemetry-proto)