Loggles

A local-first log sink that turns your coding agent into a runtime companion.

Instead of copy-pasting log output into Claude or Cursor, point your app at Loggles. Your agent queries exactly what it needs — filtered by service, level, trace ID, or time window — and gets back structured data it can reason over. No token waste, no manual copy-paste.

Your App  ──OTLP──▶  Loggles  ──MCP──▶  Claude Code / Cursor

Two use cases, same setup:

• Investigating a bug — Claude reads your source, traces the failure through logs, and points to the line. You describe the problem; it does the digging.
• Watching runtime behaviour — Ask "what did my app do when I hit that endpoint?" and Claude tails the logs, traces the request, and narrates what happened. Like a live debugger, without attaching one.

---

Quick start

Docker

docker run -d \
  -p 5000:5000 \
  -v loggles-data:/data \
  ghcr.io/bytesquashcom/loggles:latest

Add -e Auth__ApiKey=your-secret-key to enable API key protection (see Authentication).

dotnet run

git clone https://github.com/bytesquashcom/Loggles.git
cd Loggles/src/Loggles.Api
dotnet run
# Listening on http://localhost:5000

---

Sending logs to Loggles

Point your OTLP exporter at http://localhost:5000/v1/logs using HTTP/protobuf.

.NET

// dotnet add package OpenTelemetry.Exporter.OpenTelemetryProtocol
builder.Services.AddOpenTelemetry()
    .WithLogging(logging =>
    {
        logging.AddOtlpExporter(otlp =>
        {
            otlp.Endpoint = new Uri("http://localhost:5000/v1/logs");
            otlp.Protocol = OtlpExportProtocol.HttpProtobuf;
        });
    });

Node.js

npm install @opentelemetry/sdk-node @opentelemetry/exporter-logs-otlp-http @opentelemetry/sdk-logs

const { LoggerProvider, SimpleLogRecordProcessor } = require('@opentelemetry/sdk-logs');
const { OTLPLogExporter } = require('@opentelemetry/exporter-logs-otlp-http');

const provider = new LoggerProvider();
provider.addLogRecordProcessor(
  new SimpleLogRecordProcessor(
    new OTLPLogExporter({ url: 'http://localhost:5000/v1/logs' })
  )
);
provider.register();

Python

pip install opentelemetry-exporter-otlp-proto-http opentelemetry-sdk

from opentelemetry import _logs
from opentelemetry.sdk._logs import LoggerProvider
from opentelemetry.sdk._logs.export import BatchLogRecordProcessor
from opentelemetry.exporter.otlp.proto.http._log_exporter import OTLPLogExporter

provider = LoggerProvider()
provider.add_log_record_processor(
    BatchLogRecordProcessor(OTLPLogExporter(endpoint="http://localhost:5000/v1/logs"))
)
_logs.set_logger_provider(provider)

Go

go get go.opentelemetry.io/otel/exporters/otlp/otlplog/otlploghttp

exporter, _ := otlploghttp.New(context.Background(),
    otlploghttp.WithEndpointURL("http://localhost:5000/v1/logs"),
    otlploghttp.WithInsecure(),
)
provider := log.NewLoggerProvider(
    log.WithProcessor(log.NewBatchProcessor(exporter)),
)
global.SetLoggerProvider(provider)

Java

<!-- pom.xml -->
<dependency>
  <groupId>io.opentelemetry</groupId>
  <artifactId>opentelemetry-exporter-otlp</artifactId>
</dependency>

OtlpHttpLogRecordExporter exporter = OtlpHttpLogRecordExporter.builder()
    .setEndpoint("http://localhost:5000/v1/logs")
    .build();

SdkLoggerProvider provider = SdkLoggerProvider.builder()
    .addLogRecordProcessor(BatchLogRecordProcessor.builder(exporter).build())
    .build();

OpenTelemetrySdk.builder().setLoggerProvider(provider).buildAndRegisterGlobal();

Ruby

gem install opentelemetry-exporter-otlp opentelemetry-sdk

require 'opentelemetry/sdk'
require 'opentelemetry/exporter/otlp'

OpenTelemetry::SDK.configure do |c|
  c.add_span_processor(
    OpenTelemetry::SDK::Logs::Export::BatchLogRecordProcessor.new(
      OpenTelemetry::Exporter::OTLP::LogsExporter.new(
        endpoint: 'http://localhost:5000/v1/logs'
      )
    )
  )
end

PHP

composer require open-telemetry/exporter-otlp open-telemetry/sdk

$exporter = (new \OpenTelemetry\Contrib\Otlp\LogsExporter(
    \OpenTelemetry\Contrib\Otlp\OtlpUtil::createTransport('http://localhost:5000/v1/logs')
));

$provider = new \OpenTelemetry\SDK\Logs\LoggerProvider(
    new \OpenTelemetry\SDK\Logs\Processor\BatchLogRecordProcessor($exporter)
);

\OpenTelemetry\API\Logs\NoopLogger::setLoggerProvider($provider);

Any other language / collector

Set your OTLP exporter endpoint to http://localhost:5000/v1/logs using HTTP/protobuf transport. HTTP/JSON is also supported with Content-Type: application/json.

---

Connecting your coding agent

Claude Code

claude mcp add loggles --transport http http://localhost:5000/mcp

If an API key is configured, Claude Code negotiates authentication automatically via the OAuth PKCE flow — no manual token setup required.

Debug skill

This repository ships a Claude Code skill (.claude/skills/loggles-debug/) that activates automatically when you describe a bug, ask Claude to investigate an error, or want to observe your app's runtime behaviour. It puts Claude in one of two modes:

Investigative (something is broken):

• Reads your source code first to understand the relevant service, map its log output, and identify error branches — then queries logs with that context
• Cross-references log evidence against source to confirm a root cause and point to a specific file and line
• Calls out missing instrumentation (correlation_id not propagated, IDs embedded in message strings) and explains the fix

Exploratory (observing runtime behaviour):

• Starts from the logs directly — no upfront source reading
• Tails live streams, traces requests by ID, and narrates what the service is actually doing
• Useful during development and testing: "what did my app do when I hit that endpoint?"

The skill is loaded automatically when you open this project in Claude Code. To use it in your own application's repository, copy it:

mkdir -p /your-project/.claude/skills
cp -r /path/to/loggles/.claude/skills/loggles-debug /your-project/.claude/skills/

Cursor

Add to .cursor/mcp.json in your project root:

{
  "mcpServers": {
    "loggles": {
      "url": "http://localhost:5000/mcp"
    }
  }
}

If an API key is configured, add an Authorization: Bearer <key> header in your MCP client configuration.

---

MCP tools

Tool	Description
search_logs	Search with filters: time range, level, service, message text, structured properties. Supports pagination.
get_log_by_id	Retrieve a single log event by ID
get_services	List all source/service names that have emitted logs
get_log_levels	List distinct log levels present
get_properties	List distinct structured property keys
get_property_values	List distinct values for a property key within a time window
get_log_stats	Log counts grouped by level and service
get_logs_by_trace_id	Retrieve all logs sharing a trace/correlation ID
get_related_logs	Context window of logs around a specific event
get_recent_errors	Last N error/critical log events, optionally filtered by service
tail_logs	Most recent N log events
get_log_rate	Bucketed log counts over time — observe traffic volume and rhythm
get_message_templates	List distinct message templates, optionally filtered by service
find_log_patterns	Cluster messages by recurring pattern
get_error_spikes	Detect time buckets where error count exceeded a threshold
audit_log_quality	Report instrumentation coverage: missing templates, unstructured messages, broken down by service
clear_logs	Delete all log events from the store

---

Authentication

By default, with no key configured, all endpoints are open — zero friction for localhost use.

No authentication (default)

Leave Auth__ApiKey unset. All endpoints are publicly accessible. Suitable for localhost.

API key

# Docker
docker run ... -e Auth__ApiKey=your-secret-key ...

# dotnet run
export Auth__ApiKey=your-secret-key
dotnet run

Once set, all ingest and query endpoints require:

Authorization: Bearer your-secret-key

MCP clients (Claude Code, Cursor, etc.)

MCP clients that support OAuth (such as Claude Code) negotiate authentication automatically. When an API key is configured, Loggles exposes a local OAuth 2.0 + PKCE flow (RFC 6749 / RFC 7636) that issues your API key as the access token. The client handles this handshake transparently.

Discovery endpoints used by OAuth-aware clients:

Endpoint	Description
GET /.well-known/oauth-authorization-server	OAuth server metadata (RFC 8414)
GET /.well-known/oauth-protected-resource	Protected resource metadata
POST /oauth/register	Dynamic client registration (RFC 7591)
GET /oauth/authorize	Authorization endpoint
POST /oauth/token	Token endpoint — returns your configured API key

The OAuth flow can be toggled with Mcp__OAuthEnabled (default: true). Set to false to suppress discovery endpoints if your client does not support OAuth.

---

Configuration

All settings can be overridden with environment variables using __ as separator (e.g. Retention__Hours=24).

Setting	Default	Description
Storage__Provider	sqlite	Storage backend: sqlite or postgres
Storage__ConnectionString	Data Source=logs.db	SQLite connection string, or PostgreSQL connection string when using postgres provider
Retention__Hours	48	How long to keep logs
Retention__PurgeIntervalMinutes	15	How often to run cleanup
Mcp__Enabled	true	Enable/disable the MCP endpoint
Mcp__OAuthEnabled	true	Expose OAuth discovery and token endpoints for MCP clients
Auth__ApiKey	(empty)	Static API key for Bearer token auth. If unset, auth is disabled
SelfDiagnostics__Enabled	true	Send Loggles' own logs back to itself via OTLP
SelfDiagnostics__OtlpEndpoint	http://localhost:5000	OTLP endpoint for self-diagnostics

PostgreSQL

docker run -d \
  -p 5000:5000 \
  -e Storage__Provider=postgres \
  -e Storage__ConnectionString="Host=your-host;Database=loggles;Username=loggles;Password=secret" \
  ghcr.io/bytesquashcom/loggles:latest

---

REST API

Beyond MCP, a REST API is available for scripting or manual queries.

Method	Path	Description
POST	/v1/logs	Ingest OTLP/HTTP logs (protobuf or JSON)
POST	/search	Search logs with filters
GET	/logs/{id}	Get log by ID
GET	/meta/properties	List distinct property keys
GET	/stats/levels	Log counts by level

---

License

Elastic License 2.0 — free to use, self-host, and modify. You may not offer Loggles as a hosted or managed service to third parties.