[UBP ] Allow users to apply promotion codes for coupons in the UBP payment form

[gtsiolis]

Problem to solve

Some Gitpod programs will use Stripe coupons with predefined discounts and expirations.

Entering these coupons manually (by Gitpod admins) is doable through the Stripe dashboard, but it would be better if this were self-serve, and users could perform this actions on their own while setting up their billing account in Gitpod.

Unfortunately, Stripe promotion codes cannot be used in the Stripe self-service Portal in our case. Customers can only use the portal to cancel (not modify) their subscriptions. See https://stripe.com/docs/customer-management/get-started#limitations

This suggests that we need to extend our payment configuration form to accept promo codes on initial configuration.

See investigation in comments below, and discussion (internal).

An ideal solution would be one where a promo-code could be applied not just during the initial signup, but also later once the subscription is active.

[jankeromnes]

Hmm -- according to the Stripe docs, it seems that promotion codes can only be added in a "checkout" flow, which we don't use (we only use a "setup" flow, where you add your credit card details, and your subscription is then created automatically by Gitpod behind the scenes).

I think that's why, even though we do allow Stripe users to use promotion codes:

there doesn't seem to be any way in the Stripe customer portal to add a promotion code to your existing subscription:

I think we may need to have some custom UI to apply coupon codes, maybe. 🤔

[jldec]

According to https://stripe.com/docs/billing/subscriptions/coupons#promotion-codes

If you’ve implemented the customer portal and turned on promotion codes, customers can apply a discount to their existing subscriptions in the portal.