Stripe Checkout

Processes a payment through Stripe's API with authentication, status checking, retry logic, and Slack notification.

Full source

# Stripe Checkout
# Processes a payment through Stripe's API with authentication,
# status checking, retry logic, and Slack notification.

config:
    name: "Stripe Checkout"
    version: 1

services:
    Stripe is an API at "https://api.stripe.com/v1"
        with headers:
            Authorization: "Bearer {env.STRIPE_SECRET_KEY}"
    SlackNotifier is a webhook at "https://hooks.slack.com/services/placeholder"

workflow:
    trigger: when a checkout is submitted

    set email to request.customer_email
    set amount to request.amount
    set currency to request.currency
    log "Processing payment of {amount} {currency} for {email}"

    step CreateCharge:
        create charge using Stripe with amount amount and currency currency and receipt_email email
            save the result as charge
            save the status as status-code
            on failure:
                retry 3 times waiting 5 seconds
                if still failing:
                    log "Payment failed after 3 retries"
                    reject with "We could not process your payment. Please try again later."

    step VerifyPayment:
        if status-code is 200:
            log "Payment successful: {charge.id}"
        otherwise:
            log "Unexpected status: {status-code}"
            reject with "Payment was not completed successfully"

    step NotifyTeam:
        send notification using SlackNotifier with text "Payment received: {amount} {currency} from {email}"

    log "Checkout complete"
    complete with status "paid" and charge-id charge.id and email email

What this does

1. Reads checkout data from the incoming request (email, amount, currency)
2. Creates a charge through the Stripe API with Bearer token authentication
3. Retries up to 3 times if the API call fails, waiting 5 seconds between attempts
4. Checks the HTTP status — rejects the workflow if the charge didn't succeed
5. Notifies the team via a Slack webhook
6. Completes with the payment status and charge ID

Concepts demonstrated

• Authenticated API headers — with headers: block with env var interpolation
• HTTP status checking — save the status as status-code + conditional on status
• Retry with real delays — retry 3 times waiting 5 seconds
• Webhook services — SlackNotifier is a webhook at "..."
• Multiple outputs — complete with status "paid" and charge-id charge.id and email email
• Nested dot access — charge.id to read fields from API responses

Running it

# Test with mock services (no API keys needed)
flow run examples/stripe-checkout.flow --mock \
  --input '{"customer_email": "ada@example.com", "amount": 5000, "currency": "usd"}'

# Run with real Stripe (requires env vars)
export STRIPE_SECRET_KEY=sk_test_...
flow run examples/stripe-checkout.flow \
  --input '{"customer_email": "ada@example.com", "amount": 5000, "currency": "usd"}'

As a webhook

flow serve examples/stripe-checkout.flow --mock

curl -X POST http://localhost:3000 \
  -H "Content-Type: application/json" \
  -d '{"customer_email": "ada@example.com", "amount": 5000, "currency": "usd"}'