Elixir Phoenix Telemetry Integration

Implementation evidence

Elixir Phoenix Telemetry Integration: from boundary to verified row

Use Elixir Phoenix Telemetry Integration at a controlled application boundary, keep the event contract small, and verify a known outcome before building aggregate views.

1
Choose the outcome
Phoenix API reliability
2
Define the contract
route_template, method, status_code, status, duration_ms, and release
3
Instrument the boundary
Attach once during application startup and handle the terminal Phoenix endpoint or router-dispatch stop event; convert native duration units with System.convert_time_unit/3.
4
Verify the evidence
Exercise a known fixture, then inspect your_event_table for one correctly typed terminal row.

Before you start

Prerequisites and boundaries

Phoenix endpoint telemetry enabled and a supervised application process that installs handlers once
A server-side HTTP client with bounded connect and response timeouts
A route-template, status, and controlled error taxonomy that excludes request parameters and connection contents

Delivery setup

Install and initialize server-side

Use a supervised client process with a server-side key, bounded HTTP timeouts, and explicit retry limits. Keep ingestion credentials out of browser bundles, client-visible environment variables, source control, logs, and exception messages.

1Prepare one reusable server-side delivery client with bounded network behavior.
2Add the outcome event at the success, failure, retry, or timeout boundary.
3Send controlled fixtures and inspect the stored rows before enabling an alert.

Snippet

Start with one structured event

Add this shape where the workflow completes, fails, or retries. Then build the dashboard from real fields.

elixir-phoenix

Elixir Phoenix Telemetry Integration event

elixir

defmodule MyAppWeb.TelemetryOutcome do
  def attach do
    :telemetry.attach(
      "telemetry-phoenix-request-outcome",
      [:phoenix, :endpoint, :stop],
      &__MODULE__.handle_stop/4,
      nil
    )
  end

  def handle_stop(_event, measurements, metadata, _config) do
    conn = metadata.conn

    event = %{
      route_template: conn.private[:phoenix_route] || "unmatched",
      method: conn.method,
      status_code: conn.status,
      status: if(conn.status < 500, do: "success", else: "failed"),
      duration_ms:
        System.convert_time_unit(measurements.duration, :native, :millisecond),
      release: System.get_env("APP_RELEASE", "development")
    }

    # Supervise this app-owned client and give it bounded HTTP timeouts.
    MyApp.TelemetryIngest.enqueue("phoenix_request_completed", event)
  end
end

Event contract

route_template, method, status_code, status, duration_ms, and release

request_id, account_id, environment, node_role, and controlled error_type when approved

No conn.params, query string, request or response body, session, authorization header, stack trace, or unrestricted metadata

Implementation checkpoints

Checkpoint 1

Attach once during application startup and handle the terminal Phoenix endpoint or router-dispatch stop event; convert native duration units with System.convert_time_unit/3.

Checkpoint 2

Phoenix and Plug stop events do not constitute a complete distributed span, and Plug documents cases where a stop event is not emitted after an error. Retain exception and trace tooling for that diagnostic boundary.

Checkpoint 3

Forward asynchronously through a supervised, bounded delivery path so telemetry HTTP latency cannot extend the user request or destabilize the application mailbox.

Verification

Prove the event arrived

Run this after exercising known success and failure cases. Replace the fallback table name if your final event contract differs from the snippet.

elixir-phoenix-verification

Elixir Phoenix Telemetry Integration verification query

sql

SELECT *
FROM your_event_table
ORDER BY timestamp_utc DESC
LIMIT 20;

Confirm one terminal row per logical outcome, with the expected status, identifiers, units, and UTC time.

Inspect the inferred schema and verify that retries do not change field types or generate a new logical event ID.

Search the stored fields for credentials, raw payloads, prompts, private content, and unbounded error messages.

Exercise a provider timeout, ingestion rejection, and process shutdown before treating the dashboard as complete.

Implementation references

Review the event contract, data-safety guidance, and upstream primary documentation before enabling a new production path.

Application telemetry guide API reliability monitoring API latency SQL Phoenix telemetry events Plug.Telemetry lifecycle boundary

Production boundary

Keep the outcome event small and recoverable

This pattern provides

A bounded, SQL-ready outcome beside the upstream workflow.
Stable fields for dashboards, alerts, and cross-event correlation.
A fixture-driven path for validating success, failure, retry, and timeout behavior.

This pattern does not provide

An OTLP exporter, automatic collection pipeline, or replacement for detailed traces and diagnostic logs.
Exactly-once delivery merely because the payload contains an event ID.
Permission to collect raw provider payloads, user content, credentials, or regulated data.

Delivery and idempotency Batching and shutdown Troubleshoot ingestion

Event schema starting points

Review the row grain, emit boundary, required types, privacy classes, example payload, and validation checklist before adapting a query or snippet to production.

API reliability10 fields

api_request_completed

One completed API request.

Inspect contract

Continue this workflow in Alerts