Ghost to ConvertKit Connector

index.js

/*
Serverless Function to connect Ghost to ConvertKit

Required Enviroment Vairables:
API_KEY  -  Your ConvertKit API Key
FORM_ID  -  The ConvertKit form's ID you wish to subscribe users to
TAG_ID   -  Tag to mark users with in ConvertKit

Ghost Settings:
In Ghost create a new custom integration and add webhooks for new member and
updated member. Point the webhooks to your serverless function. (I'm running mine on Cloudflare Workers)

Note: To disable the Tag functionality simply comment out line 42. Tags are optional in ConvertKit.
Also, to find the FORM_ID and TAG_ID you will need to look at the URL in the ConvertKit dashboard.

*/

async function gatherResponse(response) {
  const { headers } = response
  const contentType = headers.get("content-type") || ""
  if (contentType.includes("application/json")) {
    return JSON.stringify(await response.json())
  }
  else if (contentType.includes("application/text")) {
    return await response.text()
  }
  else if (contentType.includes("text/html")) {
    return await response.text()
  }
  else {
    return await response.text()
  }
}

async function sendUser(user_name, user_email){
  const convertkit_url = 'https://api.convertkit.com/v3/forms/' + FORM_ID + '/subscribe'
  const convertkit_key = API_KEY
  const convertkit_data = {
    api_key: convertkit_key,
    email: user_email,
    first_name: user_name,
    tags: [{TAG_ID}]
  }
  const init = {
    body: JSON.stringify(convertkit_data),
    method: "POST",
    headers: {
      "content-type": "application/json;charset=UTF-8",
    },
  }
  const response = await fetch(convertkit_url, init)
  const results = await gatherResponse(response)
  return new Response(results, init)
}

function simpleResponse(statusCode, message) {
  let resp = {
    message: message,
    status: statusCode
  }

  return new Response(JSON.stringify(resp), {
    headers: new Headers([["Content-Type", "application/json"]]),
    status: statusCode
  })
}

addEventListener("fetch", event => {
  event.respondWith(WebhookHandler(event.request))
})

async function WebhookHandler(request) {
  if (request.method !== "POST") {
    return simpleResponse(
      200,
      `Please send a POST request :)`
    )
  }
  try {
    const formData = await request.json()
    const headers = await request.headers
    const user_email = formData.member.current.email
    const user_name = formData.member.current.name 
    
    return await sendUser(
      user_name, 
      user_email)

  } catch (e) {
    return simpleResponse(
      200,
      `Error:  ${e} `
    )
  }
}