@kubiks/otel-resend

OpenTelemetry instrumentation for the Resend Node.js SDK. Capture spans for every Resend API call, enrich them with operation metadata, and keep an eye on message delivery from your traces.

Visualize your email operations with detailed span information including recipients, subject lines, and delivery status.

Installation

npm install @kubiks/otel-resend
# or
pnpm add @kubiks/otel-resend

Peer Dependencies: @opentelemetry/api >= 1.9.0, resend >= 3.0.0

Quick Start

import { Resend } from "resend";
import { instrumentResend } from "@kubiks/otel-resend";

const resend = instrumentResend(new Resend(process.env.RESEND_API_KEY!));

await resend.emails.send({
  from: "[email protected]",
  to: ["[email protected]"],
  subject: "Welcome",
  html: "<p>Hello world</p>",
});

instrumentResend wraps the instance you already use — no configuration changes needed. Every SDK call creates a client span with useful attributes.

What Gets Traced

This instrumentation specifically wraps the resend.emails.send method (and its alias resend.emails.create), creating a single clean span for each email send operation.

Span Attributes

Each span includes:

| Attribute | Description | Example | | ------------------------ | --------------------------------------------------- | --------------------------------------- | | messaging.system | Constant value resend | resend | | messaging.operation | Operation type | send | | resend.resource | Resource name | emails | | resend.target | Full operation target | emails.send | | resend.to_addresses | Comma-separated TO addresses | [email protected], [email protected] | | resend.cc_addresses | Comma-separated CC addresses (if present) | [email protected] | | resend.bcc_addresses | Comma-separated BCC addresses (if present) | [email protected] | | resend.recipient_count | Total number of recipients | 3 | | resend.from | Sender email address | [email protected] | | resend.subject | Email subject | Welcome to our service | | resend.template_id | Template ID (if using templates) | tmpl_123 | | resend.message_id | Message ID returned by Resend | email_123 | | resend.message_count | Number of messages sent (always 1 for single sends) | 1 |

The instrumentation captures email addresses and metadata to help with debugging and monitoring, while avoiding sensitive email content.

License

MIT