[gatsby + shopify + recurring payments] "instead of taking the user to shopify's checkout, you need to create a recharge's checkout. This can be only done from a server (backend) so you will either have to set one up or use serverless functions (I am using functions from netlify)." – https://github.com/blancomaberino - https://spectrum.chat/gats…

netlify-function.js

/* eslint-disable */
const fetch = require('node-fetch')
const rechargeToken = process.env.RECHARGE_TOKEN
const subscriptionIntervalFrequency = process.env.SUBSCRIPTION_INTERVAL_FREQUENCY || 30
const subscriptionIntervalUnit = process.env.SUBSCRIPTION_INTERVAL_UNIT || 'day'
/**
 * Builds request headers
 * @return {Array}
 */
const buildHeaders = () => ({
  'X-Recharge-Access-Token': rechargeToken,
  'Accept': 'application/json',
  'Content-Type': 'application/json'
})
exports.handler = async function(event, context) {
  try {
    const params = JSON.parse(event.body)
    if (!params || !params.line_items) {
      return { statusCode: 400, body: JSON.stringify({
        message: 'Missing parameters',
        data: ['line_items']
      }) }
    }
    const line_items = params.line_items.map((item) => {
      item = {
        ...item
      }
       // Without information below, item will be treated as `one-time` product and not generate a subscription, so you may want to use it for non-subscription products and unify everything under recharge's checkout instead of using shopify's one for non-subscription and recharge's for subscriptions.
      if (item.is_subscription === true) {
        item.charge_interval_frequency = subscriptionIntervalFrequency
        item.order_interval_frequency = subscriptionIntervalFrequency
        item.order_interval_unit = subscriptionIntervalUnit
      }
      delete item.is_subscription
      return item      
    })
    const checkoutApiUrl = 'https://api.rechargeapps.com/checkouts'
    const response = await fetch(checkoutApiUrl, {
      headers: buildHeaders(),
      method: 'post',
      body: JSON.stringify({
        line_items
      })
    })
    if (!response.ok) {
      throw response
    }
    const data = await response.json()
    const checkoutUrl = `https://checkout.rechargeapps.com/r/checkout/${data.checkout.token}?myshopify_domain=${process.env.SHOPIFY_SHOP_NAME}.myshopify.com`
    return {
      statusCode: 200,
      body: JSON.stringify({
        webUrl: checkoutUrl
      })
    }
  } catch (err) {
    // console.log(err) // output to netlify function log
    return {
      statusCode: err.statusCode || 500,
      body: JSON.stringify({ message: err.statusText || err.message || 'Internal Server Error' }) // Could be a custom message or object i.e. JSON.stringify(err)
    }
  }
}