Otel

Pure Elixir, OpenTelemetry-compatible

Features

• Signals
  • Traces
  • Metrics
  • Logs
• Propagators
  • W3C TraceContext
  • W3C Baggage
• Exporters
  • OTLP/HTTP (Protobuf)
• Integrations
  • :logger bridge
  • :telemetry bridge

Requirements

• Elixir ~> 1.18
• Erlang/OTP ~> 26.2

Compatibility

Installation

Add :otel to deps in mix.exs:

def deps do
  [
    {:otel, "~> 0.4.0"}
  ]
end

Configuration

SDK

# config/config.exs
config :otel, otp_app: :my_app, req_options: []

:req_options is forwarded to Req.new/1 — see :req for the full option list.

Logs

# config/config.exs
config :kernel,
  logger: [
    {:handler, :otel, Otel.LoggerHandler, %{}}
  ]

Otel.LoggerHandler bridges Logger — see :logger for log levels and metadata.

Metrics

# lib/my_app/application.ex
children = [
  {Otel.TelemetryReporter, metrics: []}
]

Otel.TelemetryReporter bridges Telemetry.Metrics — see :telemetry_metrics for metric definitions.

Trace

# lib/my_app/application.ex
children = [
  {Otel.TelemetryTracer, events: []}
]

Otel.TelemetryTracer bridges :telemetry.span/3 — see :telemetry for instrumentation.

Optional: Otel.TelemetrySpanDecorator

# lib/my_app/calculator.ex
defmodule MyApp.Calculator do
  use Otel.TelemetrySpanDecorator

  @span [:my_app, :calculator, :add]
  def add(a, b), do: a + b

  @span event: [:my_app, :calculator, :sub], capture_io: true
  def sub(a, b), do: a - b
end

@span auto-wraps the function body in :telemetry.span/3 and injects code.function.name / code.file.path / code.line.number; pass capture_io: true to also record arguments and the return value.

License

Released under the MIT License.