Twilio (SMS)

Send SMS messages via Twilio's Programmable Messaging API. You can use the official SDK or hit the REST endpoint directly with fetch.

Account setup

From the Twilio Console grab:

• TWILIO_ACCOUNT_SID
• TWILIO_AUTH_TOKEN
• TWILIO_FROM_NUMBER (in E.164 format, e.g. +15551234567)

Installation (SDK)

pnpm add twilio

Configure the client

src/clients/twilio.ts

import twilio from "twilio";

export const twilioClient = twilio(
  process.env.TWILIO_ACCOUNT_SID!,
  process.env.TWILIO_AUTH_TOKEN!
);

Define the effect

src/effects/twilio.ts

import { createEffect, S } from "envio";
import { twilioClient } from "../clients/twilio";

export const sendSms = createEffect(
  {
    name: "sendSms",
    input: { to: S.string, body: S.string },
    rateLimit: { calls: 1, per: "second" }, // Twilio default trial = 1 msg/sec
    mode: "orderedAfterCommit",
  },
  async ({ input }) => {
    await twilioClient.messages.create({
      from: process.env.TWILIO_FROM_NUMBER!,
      to: input.to,
      body: input.body,
    });
  }
);

Raw fetch alternative

If you'd rather skip the SDK:

const auth = Buffer.from(
  `${process.env.TWILIO_ACCOUNT_SID}:${process.env.TWILIO_AUTH_TOKEN}`
).toString("base64");

await fetch(
  `https://api.twilio.com/2010-04-01/Accounts/${process.env.TWILIO_ACCOUNT_SID}/Messages.json`,
  {
    method: "POST",
    headers: {
      Authorization: `Basic ${auth}`,
      "Content-Type": "application/x-www-form-urlencoded",
    },
    body: new URLSearchParams({
      From: process.env.TWILIO_FROM_NUMBER!,
      To: input.to,
      Body: input.body,
    }),
  }
);

Call it from a handler

The rindexer config…

chat:
  twilio:
    - account_sid: ${TWILIO_ACCOUNT_SID}
      auth_token: ${TWILIO_AUTH_TOKEN}
      from_number: ${TWILIO_FROM_NUMBER}
      to_number: ${TWILIO_TO_NUMBER}
      messages:
        - event_name: Transfer
          filter_expression: "value >= 10"
          template_inline: "Transfer detected: {{value}} tokens"

…becomes:

src/EventHandlers.ts

import { RocketPoolETH } from "generated";
import { sendSms } from "./effects/twilio";
import { formatUnits } from "./utils/format";

const TO = process.env.TWILIO_TO_NUMBER!;

RocketPoolETH.Transfer.handler(async ({ event, context }) => {
  const { value } = event.params;
  if (value < 10n) return;

  context.effect(sendSms, {
    to: TO,
    body: `Transfer detected: ${formatUnits(value)} RETH`,
  });
});

SMS is rate-limited and expensive — keep your conditions strict.