Eliot.Logger (Eliot v0.2.0)

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Centralized logging for the Eliot IoT data ingestion system.

Provides structured logging with telemetry integration for comprehensive observability of device communications, data processing, and system events.

Features

  • Structured logging with metadata enrichment
  • Telemetry event integration for system monitoring
  • Device-specific event tracking
  • MQTT connection lifecycle logging
  • Data processing performance metrics
  • Automatic statistics reporting

Usage

# Basic logging
Eliot.Logger.log_info("System started", %{component: "application"})
Eliot.Logger.log_error("Connection failed", %{retry_count: 3})

# Device event logging
Eliot.Logger.log_device_event("sensor_001", "temperature_reading", %{
  temperature: 23.5,
  humidity: 65.0
})

# MQTT event logging
broker_config = %{host: "mqtt.example.com", port: 1883}
Eliot.Logger.log_mqtt_event("connection_established", broker_config)

# Processing event logging
Eliot.Logger.log_processing_event("msg_123", 150, "success")

All logging functions automatically emit corresponding telemetry events for integration with monitoring and alerting systems.

Summary

Functions

child_spec(init_arg)

Returns a specification to start this module under a supervisor.

handle_telemetry_event(event_name, measurements, metadata, config)

Handles telemetry events for system-wide logging.

log_device_event(device_id, event_type, data \\ %{})

Logs device-specific events with standardized metadata.

log_error(message, metadata \\ %{})

Logs an error-level message with structured metadata.

log_info(message, metadata \\ %{})

Logs an info-level message with structured metadata.

log_mqtt_event(event_type, broker_info, data \\ %{})

Logs MQTT-related events with connection metadata.

log_processing_event(message_id, processing_time_ms, result)

Logs data processing events with performance metrics.

log_warning(message, metadata \\ %{})

Logs a warning-level message with structured metadata.

start_link(opts \\ [])

Starts the logger GenServer.

Functions

child_spec(init_arg)

Returns a specification to start this module under a supervisor.

See Supervisor.

handle_telemetry_event(event_name, measurements, metadata, config)

Handles telemetry events for system-wide logging.

This function is defined as a module function to avoid the telemetry performance warning about local functions.

log_device_event(device_id, event_type, data \\ %{})

Logs device-specific events with standardized metadata.

Automatically enriches the event with timestamp and device information, then emits a telemetry event for monitoring systems.

Parameters

  • device_id - Unique identifier for the device
  • event_type - Type of event (e.g., "sensor_reading", "connection_lost")
  • data - Optional event-specific data (default: %{})

Examples

# Simple device event
Eliot.Logger.log_device_event("sensor_001", "online")

# Device event with sensor data
Eliot.Logger.log_device_event("thermometer_42", "temperature_reading", %{
  temperature: 23.5,
  humidity: 65.0,
  battery_level: 87
})

log_error(message, metadata \\ %{})

Logs an error-level message with structured metadata.

Parameters

  • message - The log message string
  • metadata - Optional map of structured metadata (default: %{})

Examples

Eliot.Logger.log_error("Database connection failed")
Eliot.Logger.log_error("API request timeout", %{endpoint: "/api/data", timeout_ms: 5000})

log_info(message, metadata \\ %{})

Logs an info-level message with structured metadata.

Parameters

  • message - The log message string
  • metadata - Optional map of structured metadata (default: %{})

Examples

Eliot.Logger.log_info("System initialized successfully")
Eliot.Logger.log_info("User authenticated", %{user_id: "123", method: "oauth"})

log_mqtt_event(event_type, broker_info, data \\ %{})

Logs MQTT-related events with connection metadata.

Tracks MQTT broker interactions including connections, disconnections, message publishing, and subscription events.

Parameters

  • event_type - Type of MQTT event (e.g., "connection_established", "message_published")
  • broker_info - Map containing broker connection details
  • data - Optional event-specific data (default: %{})

Examples

broker_config = %{host: "mqtt.example.com", port: 1883, client_id: "eliot_001"}

# Connection event
Eliot.Logger.log_mqtt_event("connection_established", broker_config)

# Message publishing event
Eliot.Logger.log_mqtt_event("message_published", broker_config, %{
  topic: "sensors/temperature",
  qos: 1,
  payload_size: 128
})

log_processing_event(message_id, processing_time_ms, result)

Logs data processing events with performance metrics.

Tracks message processing performance and outcomes for monitoring system throughput and identifying bottlenecks.

Parameters

  • message_id - Unique identifier for the processed message
  • processing_time_ms - Processing duration in milliseconds
  • result - Processing outcome (e.g., "success", "error", "timeout")

Examples

# Successful processing
Eliot.Logger.log_processing_event("msg_12345", 150, "success")

# Failed processing
Eliot.Logger.log_processing_event("msg_12346", 2500, "timeout")

log_warning(message, metadata \\ %{})

Logs a warning-level message with structured metadata.

Parameters

  • message - The log message string
  • metadata - Optional map of structured metadata (default: %{})

Examples

Eliot.Logger.log_warning("High memory usage detected")
Eliot.Logger.log_warning("Rate limit approaching", %{current_rate: 95, limit: 100})

start_link(opts \\ [])

Starts the logger GenServer.

Options

  • :name - The name to register the GenServer under (default: __MODULE__)

Examples

{:ok, pid} = Eliot.Logger.start_link()
{:ok, pid} = Eliot.Logger.start_link(name: MyLogger)