Essential OpenTelemetry OTLP File Exporter

OTLP File exporter for OpenTelemetry .NET that outputs OpenTelemetry signals to stdout (console) in JSONL format compatible with the OpenTelemetry Protocol File Exporter specification and the OpenTelemetry Collector JSON File Receiver.

This exporter is part of the Essential .NET OpenTelemetry project, which provides guidance, additional exporters, and extensions for .NET OpenTelemetry implementations.

NOTE: This alpha version only supports console output. Future versions will include configuration for specific output files, along with rotation options based on the Collector format.

Features

• Outputs logs, spans, and traces in OTLP protobuf JSON format (one JSON object per line)
• Compatible with OpenTelemetry Collector file exporter/receiver
• Supports structured logging with semantic attributes

Installation

Install the required NuGet packages via dotnet or another package manager:

dotnet add package OpenTelemetry.Extensions.Hosting dotnet add package Essential.OpenTelemetry.Exporter.OtlpFile

Usage

The exporter can be configured as a standard OpenTelemetry exporter for a host based application.

• Add the required packages
• Reference the required namespaces
• Clear the default logging providers (so there is no other console output)
• Add the OtlpFileExporter

using System; using Essential.OpenTelemetry; using Microsoft.AspNetCore.Builder; using Microsoft.Extensions.DependencyInjection; using Microsoft.Extensions.Logging; using OpenTelemetry.Metrics; using OpenTelemetry.Trace; var builder = WebApplication.CreateBuilder(args); // Clear default logging builder.Logging.ClearProviders(); // Add OpenTelemetry with OTLP File exporter builder .Services.AddOpenTelemetry() .WithLogging(logging => { logging.AddOtlpFileExporter(); }) .WithTracing(tracing => { tracing.AddAspNetCoreInstrumentation().AddOtlpFileExporter(); }) .WithMetrics(metrics => { metrics .AddAspNetCoreInstrumentation() .AddView(instrument => instrument.Name.StartsWith("http.server.request", StringComparison.Ordinal) ? null : MetricStreamConfiguration.Drop ) .AddOtlpFileExporter(options => { }, exportIntervalMilliseconds: 60_000); }); var app = builder.Build(); app.MapGet("/", () => "Hello World!"); app.Run();

Output Format

The exporter outputs one JSON object per line in OTLP protobuf JSON format. The example is here is formatted for readability, but is output as a single line (JSONL) by the exporter.

{ "resourceLogs": [ { "resource": { "attributes": [] }, "scopeLogs": [ { "scope": { "name": "Program" }, "logRecords": [ { "timeUnixNano": "1771035371041000000", "observedTimeUnixNano": "1771035371041000000", "severityNumber": 9, "severityText": "Information", "body": { "stringValue": "Hello from Alice" }, "attributes": [ { "key": "Name", "value": { "stringValue": "Alice" } } ] } ] } ] } ] }

Using with OpenTelemetry Collector

You can pipe the output to a file and use it with the OTLP JSON File Receiver:

dotnet run > logs.jsonl

License

Essential.OpenTelemetry OtlpFile Exporter - OTLP JSON file output for OpenTelemetry logs, traces, and metrics. Copyright (C) 2026 Gryphon Technology Pty Ltd

This library is free software: you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License and GNU General Public License for more details.

You should have received a copy of the GNU Lesser General Public License and GNU General Public License along with this library. If not, see https://www.gnu.org/licenses/.