Trigger Studio Flow via Segment Destination Function

function.js

async function onIdentify(event, settings) {
	let response;
	try {
		const profileApiResponse = await fetch(
			`https://profiles.segment.com/v1/spaces/${
				event.context.personas.space_id
			}/collections/users/profiles/user_id:${encodeURIComponent(
				event.userId
			)}/traits`,
			{
				method: 'GET',
				headers: {
					Authorization: `Basic ${btoa(settings.profileApiKey + ':')}`
				}
			}
		);
		const profile = await profileApiResponse.json();

		const phone = profile.traits.isWhatsApp
			? `whatsapp:${event.userId}`
			: event.userId;

		// Create the user in the system after
		await fetch(`https://${settings.functionDomain}/users/add`, {
			method: 'POST',
			headers: {
				'Content-Type': 'application/json'
			},
			body: JSON.stringify({ phone })
		});

		response = await fetch(
			`https://studio.twilio.com/v2/Flows/${settings.flowSid}/Executions `,
			{
				method: 'POST',
				headers: {
					Authorization: `Basic ${btoa(
						settings.twilioAccountId + ':' + settings.twilioAuthToken
					)}`,
					'Content-Type': 'application/x-www-form-urlencoded;charset=UTF-8'
				},
				body: toFormParams({
					To: phone,
					From: settings.messagingServiceSid
				})
			}
		);
	} catch (error) {
		// Retry on connection error
		throw new RetryError(error.message);
	}

	if (response.status >= 500 || response.status === 429) {
		// Retry on 5xx (server errors) and 429s (rate limits)
		throw new RetryError(`Failed with ${response.status}`);
	}
}

function toFormParams(params) {
	return Object.entries(params)
		.map(([key, value]) => {
			const paramName = encodeURIComponent(key);
			const param = encodeURIComponent(value);
			return `${paramName}=${param}`;
		})
		.join('&');
}

This function first retrieves the traits from the Profile API and then uses the Twilio API to trigger a Studio Flow:

This is the needed config: