Set Up Tracing

Learn how to enable tracing in your app and discover valuable performance insights of your application.

With tracing, Sentry tracks your software performance, measuring metrics like throughput and latency, and displaying the impact of errors across multiple systems.

Sentry's Elixir SDK uses OpenTelemetry for tracing. Add the required dependencies to your mix.exs:

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def deps do
  [
    # Sentry SDK
    {:sentry, "~> 11.0"},

    # OpenTelemetry core packages
    {:opentelemetry, "~> 1.5"},
    {:opentelemetry_api, "~> 1.4"},
    {:opentelemetry_exporter, "~> 1.0"},
    {:opentelemetry_semantic_conventions, "~> 1.27"},

    # Instrumentation libraries (choose what you need)
    {:opentelemetry_phoenix, "~> 2.0"},      # for Phoenix
    {:opentelemetry_bandit, "~> 0.1"},       # for Bandit (Phoenix 1.7+)
    {:opentelemetry_ecto, "~> 1.2"},         # for Ecto

    # ... your other dependencies
  ]
end

Enable tracing in your Sentry configuration:

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# config/config.exs or config/dev.exs
config :sentry,
  dsn: "https://examplePublicKey@o0.ingest.sentry.io/0",
  traces_sample_rate: 1.0  # Adjust for production

Set up OpenTelemetry to send traces to Sentry:

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# config/config.exs
config :opentelemetry, span_processor: {Sentry.OpenTelemetry.SpanProcessor, []}

config :opentelemetry, sampler: {Sentry.OpenTelemetry.Sampler, []}

In your application.ex, set up the OpenTelemetry instrumentation:

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# lib/my_app/application.ex
defmodule MyApp.Application do
  use Application

  def start(_type, _args) do
    # Set up OpenTelemetry instrumentation
    OpentelemetryBandit.setup()           # for Bandit (Phoenix 1.7+)
    # OR OpentelemetryPhoenix.setup(adapter: :cowboy2)  # for Cowboy

    OpentelemetryPhoenix.setup(adapter: :bandit)
    OpentelemetryEcto.setup([:my_app, :repo], db_statement: :enabled)

    # Optional: Set up Oban instrumentation
    # OpentelemetryOban.setup()

    children = [
      # ... your supervision tree
    ]

    opts = [strategy: :one_for_one, name: MyApp.Supervisor]
    Supervisor.start_link(children, opts)
  end
end

For more control over sampling, you can use a sampling function:

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config :sentry,
  dsn: "https://examplePublicKey@o0.ingest.sentry.io/0",
  traces_sampler: fn sampling_context ->
    case sampling_context.transaction_context.op do
      "http.server" -> 0.1  # Sample 10% of HTTP requests
      _ -> 0.05             # Sample 5% of other operations
    end
  end

Learn more about tracing options.

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