opentelemetry-dotnet/docs/logs/customizing-the-sdk/README.md

Customizing OpenTelemetry .NET SDK for Logs

OpenTelemetryLoggerProvider

TODO

Building the OpenTelemetryLoggerProvider

TODO

OpenTelemetryLoggerProvider configuration

TODO

IncludeScopes

TODO

IncludeFormattedMessage

TODO

ParseStateValues

TODO

AddProcessor

TODO

SetResourceBuilder

Resource is the immutable representation of the entity producing the telemetry. If no Resource is explicitly configured, the default is to use a resource indicating this Telemetry SDK. The SetResourceBuilder method on OpenTelemetryLoggerOptions can be used to set a single ResourceBuilder. If SetResourceBuilder is called multiple times, only the last is kept. It is not possible to change the resource builder after creating the LoggerFactory.

The snippet below shows configuring a custom ResourceBuilder to the provider.

var loggerFactory = LoggerFactory.Create(builder =>
{
    builder.AddOpenTelemetry(options =>
    {
        options.SetResourceBuilder(ResourceBuilder.CreateDefault().AddService(
            serviceName: "MyService",
            serviceVersion: "1.0.0"
            ));
    });
});

See Program.cs for complete example.

It is also possible to configure the Resource by using following environmental variables:

Environment variable	Description
OTEL_RESOURCE_ATTRIBUTES	Key-value pairs to be used as resource attributes. See the Resource SDK specification for more details.
OTEL_SERVICE_NAME	Sets the value of the service.name resource attribute. If service.name is also provided in OTEL_RESOURCE_ATTRIBUTES, then OTEL_SERVICE_NAME takes precedence.

Filtering LogLevels

ILogger implementations have a built-in mechanism to apply log filtering. This filtering lets you control the logs that are sent to each registered provider, including the OpenTelemetryLoggerProvider. "OpenTelemetry" is the alias for OpenTelemetryLoggerProvider, that may be used in configuring filtering rules.

The example below defines "Error" as the default LogLevel and also defines "Warning" as the minimum LogLevel for a user defined category.

ILoggingBuilder.AddFilter<OpenTelemetryLoggerProvider>("*", LogLevel.Error);
ILoggingBuilder.AddFilter<OpenTelemetryLoggerProvider>("category name", LogLevel.Warning);

Learn more

• See also the official guide for Logging in .NET.
• LogLevel