light-telemetry

UDP fire-and-forget telemetry client for LightTelemetry — a lightweight observability daemon for test environments and embedded/bare-metal hardware where OpenTelemetry is too heavy.

Features

• Fire-and-forget — emit serializes one packet and sends one UDP datagram. No buffering, no retries: telemetry never blocks or crashes your application.
• Degradation-aware — a background watcher tracks reverse heartbeats from the server; when they stop, emissions drop before serialization (zero cost when the collector is gone).
• Two wire formats — JSON (default) or MessagePack.
• Auto-discovery — adopt the server's telemetry.toml to find the ingest endpoint and heartbeat timing automatically.
• logging integration — TelemetryLogHandler forwards logging records as telemetry events.
• MTU-safe — oversized packets are truncated to a marker, never fragmented.

Install

pip install light-telemetry
# or
uv add light-telemetry

Requires Python ≥ 3.11.

Quickstart

Zero-config localhost client

Reads telemetry.toml (/etc/telemetry.toml, then ~/.config/telemetry.toml) written by the server — target address and heartbeat timing come from the daemon itself. Falls back to 127.0.0.1:9876 if no file exists.

from light_telemetry import TelemetryClient

client = TelemetryClient.local("my-app", "service")
client.start()  # spawns the heartbeat watcher
client.emit("test.start", {"case": "can_tx", "rig": 3})
client.stop()

Explicit endpoint

from light_telemetry import TelemetryClient

with TelemetryClient(
    ("192.168.1.10", 9876),
    host_id="bench-01",
    host_class="rig",
    use_msgpack=True,  # MessagePack wire format
    heartbeat_timeout=3.0,  # s; None disables the watcher
) as client:
    client.emit("firmware.flash", {"target": "stm32", "bytes": 65536})

logging integration

import logging
from light_telemetry import TelemetryClient, TelemetryLogHandler

client = TelemetryClient.local("my-app", "service").start()
logging.getLogger().addHandler(TelemetryLogHandler(client, topic="logger"))

log = logging.getLogger("sut")
log.info("device under test ready", extra={"fw": "1.4.2"})
# every record emits: {"level", "logger", "message", + extra fields}

Server

Events land in the light-telemetry daemon, which exposes REST queries, a wait-subscription API, a WebSocket stream, and a Grafana-compatible JSON adapter. Storage backends: in-memory, SQLite, PostgreSQL.

Links

• Repository / full monorepo — https://github.com/oldienki/telemetry
• Rust client — light-telemetry-client on crates.io
• Go client — github.com/oldienki/telemetry/go/light-telemetry

License

MIT OR Apache-2.0