imrenagi/go-payment

Payment module used as proxy for multiple payment gateways. Currently it only supports Midtrans SNAP and Xendit Ewallet and XenInvoice. Support for other channels will be added incrementally.

This payment proxy is a payment service I used for my personal site. Thinking that this might be useful to help other people so that they can start accept money ASAP, so I decided to make this module open source.

Payment Channels Supported

In general, this payment proxy can support payment through this following channels:

• Recurring payment with Credit Card, OVO, Bank Transfer
• Credit card payment with/without installment
• Ewallet (GoPay, OVO, Dana, LinkAja)
• Retail Outlet (Alfamart, Alfamidi, Dan+Dan)
• Cardless Credit (Akulaku)
• Bank Transfer via Virtual Account (BCA, BNI, BRI, Mandiri, Permata, Other Bank).

❗ Recurring payment is only supported via XenditInvoice.

Why you should use this payment proxy?

• If you are planning to use Midtrans SNAP and Xendit Invoice as the UI for the payment, you are strongly encouraged to use this proxy because it supports both UIs.
• This proxy helps you managing the payment gateway used for each channel. It internally connects to both payment gateway as you need, in no time. What your API user knows is only one single API to generate Invoice
• This proxy helps you seemlesly switch the gateway for a payment channel whenever one of them is not functioning properly/down for maintenance. For instance, Bank Transfer by VA, are supported by Midtrans and Xendit. If Midtrans VA is going south, you can easily switch the gateway to Xendit simply by updating the configuration file.
• You can choose whether to absorb the admin/installment fees by yourself or to off load it to your user by changing the payment configuration written in yaml.
• This proxy can generate Invoice storing informations about the customer info, item, payment method selected, and its state. Invoice state will change over the time depends on the transaction status callback sent by payment gateway.
• You can opt-in to store payment notification callback to your database. Currently it only stores midtrans transaction status. Support for xendit will be added soon.

Current Limitations

1. For simplify the query creation for database join, I use gorm.io as the ORM library.
2. This proxy is not made for supporting all use cases available out there. It's hard requirement is just so that people can accept payment with as low effort as possible without need to worry about custom UI flow.
3. No callback trigger at least of now once the payment manager is done procesing this request. This will be the next priority of the next release. This issue is documented here
4. Callback or redirect URL is globally configured. This means, you cant configure callback for each request differently on the fly.

Implemented Channels

This tables shows which payment channels that has been implemented by this proxy.

✅ : ready

❗ : in progress

❌ : not yet supported natively by payment gateway

Getting Started

Here some preparations that you might need before using this proxy.

Payment Gateway Registration

This can be tricky. If you have personal business, this might be easier. If you have business entity (PT, CV, etc), there are some additional processes you have to follow and some documents that you have to provide. In this context, I will just assume that you have personal business like what I do: imrenagi.com

Midtrans

Please review this page before creating an account.

Xendit

Please visit this registration page for creating an account.

Midtrans VS Xendit Onboarding

Here is the comparison between Midtrans and Xendit onboarding based on my onboarding experience.

Payment Gateway Callback

Since this library is just providing the http.Handler, you can choose the REST API endpoint used by each callback. You can check the example on server.go.

Some Xendit Legacy Ewallet API(s) require you to set callback and redirect URL on the body request. You can override this value by using environment variables. Go to Mandatory Environment Variables.

Midtrans

To set your callback URL,

• Login to https://dashboard.midtrans.com
• Choose environment (Sandbox or Production)
• Click Settings > Configuration
• Set your Payment Notification URL with your server callback. For instance: https://api.imrenagi.com/payment/midtrans/callback
• Set your Finish, Unfinish, and Error redirect URL
• Click Update

Xendit

To set your callback URL,

• Login to https://dashboard.xendit.co
• Choose environment (Live or Test)
• Click Settings > Callbacks
• Set your callbacks for Invoices Paid. For instance: https://api.imrenagi.com/payment/xendit/invoice/callback
• Check option Also notify my application when an invoice is expired
• Click Save and Test

LinkAja and DANA callback URL are not defined on xendit dashboard. Instead, they are given while the proxy is initiating the payment request to Xendit API. You can find the callback URL set on linkaja.go and dana.go

Application Secret

Before using this application, you might need to update secret.yaml file containing application secret like database and payment gateway credential.

Application Config

As of now, application config stores configuration about which API that you would like to use for Xendit ewallet payments such as Dana, OVO, and LinkAja. Please check config.yaml.

xendit:
  ewallet:
    ovo:
      invoice: false
      legacy: false

• xendit.ewallet.[ewallet].invoice set to true if you want to use XenInvoice instead of using direct API integration
• xendit.ewallet.[ewallet].legacy set to true if you want to use legacy Xendit Ewallet API. Note that this API will be deprecated by first quarter of 2022.

Database

I removed MySQL as default database for this library. This library only accept instance of gorm.DB for database. Thus, you can use any database you like and provide the gorm.DB instance of chosen database.

For more, please check server.go

Midtrans Credential

• Login to https://dashboard.midtrans.com
• Choose environment (Sandbox or Production)
• Click Settings > Access Keys
• Grab the credentials, and update the secret.yaml

payment:
  midtrans:
    secretKey: "midtrans-server-secret"
    clientKey: "midtrans-client-key"
    clientId: "midtrans-merchant-id"

Xendit Credential

• Login to https://dashboard.xendit.co
• Choose environment (Live or Test)
• Click Settings > API Keys > Generate secret key
• Add key Name. Grant write permission for both Money-in products
• Take the generated API Keys and Verification Callback Token, update the secret.yaml

payment:
  ...
  xendit:
    secretKey: "xendit-api-key"
    callbackToken: "xendit-callback-token"

Configuration File

You can take a look sample configuration file named payment-methods.yml. For instance:

card_payment:
  payment_type: "credit_card"
  installments:
    - type: offline
      display_name: ""
      gateway: midtrans
      bank: bca
      channel: migs
      default: true
      active: true
      terms:
        - term: 0
          admin_fee:
            IDR:
              val_percentage: 2.9
              val_currency: 2000
              currency: "IDR"
        - term: 3
          installment_fee:
            IDR:
              val_percentage: 5.5
              val_currency: 2200
              currency: "IDR"

With above configuration, for installment offline with bca, you can apply this following fees to the invoice after user generates new invoice:

1. 2.9% + IDR 2000 admin fee for credit card transaction without any installment, or
2. 5.5% + IDR 2200 installment fee for credit card transaction with installment for 3 month tenure.

If you want to absorb the fee, you can simply set val_percentage and val_currency as 0

If you only want to apply fee just either by using val_pecentage or val_currency, simply set the value to one of them and give 0 to the other. For instance:

bank_transfers:
  - gateway: midtrans
    payment_type: "bca_va"
    display_name: "BCA"
    admin_fee:
      IDR:
        val_percentage: 0
        val_currency: 4000
        currency: "IDR"

admin_fee and installment_fee are optional key.

Mandatory Environment Variables

You need to set these environment variables to make sure this proxy to work.

Example Code

You can find the sample code in here

API Usage

You can find the details of API usage in here

Contributing

No rules for now. Feel free to add issue first and optionally submit a PR. Cheers

License

MIT. Copyright 2022 Imre Nagi