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https://github.com/OpShin/opshin-starter-kit

On-chain and off-chain code for a Python Smart Contract using opshin and pycardano
https://github.com/OpShin/opshin-starter-kit

cardano demeter-run off-chain on-chain plutus python smart-contracts

Last synced: 23 days ago
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On-chain and off-chain code for a Python Smart Contract using opshin and pycardano

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README 

        
# OpShin Starter-kit




This Starter-Kit is a small tutorial of how to use the [PyCardano](https://github.com/Python-Cardano/pycardano) library 

with [opshin](https://github.com/OpShin/opshin) for interacting with a simple vesting contract on Cardano.



PyCardano is a Cardano library written in Python. It allows users to create and sign transactions without depending on third-party Cardano serialization tools, such as cardano-cli and cardano-serialization-lib, making it a lightweight library, which is simple and fast to set up in all types of environments.



opshin is a Smart Contract language based on Python. It allows users to define and compile Smart Contracts directly within a python environment.

It also interacts seemlessly with PyCardano.



## Dev Environment



For executing the scripts in this starter kit you'll need access to a running [Ogmios](https://ogmios.dev/) instance.



In case you don't want to install the required components yourself, you can use [Demeter.run](https://demeter.run) platform to create a cloud environment with access to common Cardano infrastructure. The following command will open this repo in a private, web-based VSCode IDE with access to a running Ogmios instance in the preview network.



[![Code in Cardano Workspace](https://demeter.run/code/badge.svg)](https://demeter.run/code?repository=https://github.com/opshin/opshin-starter-kit.git&template=python&source=demeter&key=opshin-starter-kit)



## What is Included



We have included a number of python scripts for executing specific actions.

You can find scripts to initialize addresses and interact with the cardano-node in `scripts`.

`src` contains two folders, `on_chain` which hosts the actual opshin contract and `off-chain` which

hosts tooling to interact with the contract.



## Setup



1. Install Python 3.8, 3.9 or 3.10.



On demeter.run or Linux/Ubuntu, this version of python is usually already pre-installed. You can skip this step.

For other Operating Systems, you can download the installer [here](https://www.python.org/downloads/release/python-3810/).



2. Ensure `python3 --version` works in your command line. Open a Terminal in the browser VSCode interface (F1 -> Terminal: Create New Terminal)

In Windows, you can do this by copying the `python.exe` file to `python3.exe` in your `PATH` environment variable.



3. Install python poetry.



On demeter.run or Linux/Ubuntu run 

```bash

curl -sSL https://install.python-poetry.org | python3 -

```

Follow the instructions diplayed to add poetry to your local shell.



Otherwise, follow the official documentation [here](https://python-poetry.org/docs/#installation).



4. Install a python virtual environment with poetry:

```bash

# install python dependencies

poetry install

# run a shell with the virtual environment activated

poetry shell

```



5. Set up [ogmios](https://ogmios.dev/) and optionally [kupo](https://cardanosolutions.github.io/kupo/).



On demeter.run, simply add the Ogmios Extension for the Preview network

through the project console website (the page that shows you demeter.run project -> Connected Extensions -> Browse Extensions -> Cardano Ogmios)

If you want to add kupo, use the Kupo Extension as well.



Make sure the following environment variables are set (defaults are displayed):



```bash

OGMIOS_API_HOST=localhost

OGMIOS_API_PORT=1337

OGMIOS_API_PROTOCOL=ws



KUPO_API_HOST=None

KUPO_API_PORT=80

KUPO_API_PROTOCOL=http

```



## Running the scripts



Once you have entered the poetry shell, you can start interacting with the contract through the prepared scripts.



First, we have to build the vesting contract and generate two key pairs, one for the

owner of funds and one for the intended beneficiary.



```bash

python3 scripts/build.py

python3 scripts/create_key_pair.py owner

python3 scripts/create_key_pair.py beneficiary

```



Make sure that the owner is loaded up with some testnet ada before proceeding,

by using the [testnet faucet](https://docs.cardano.org/cardano-testnet/tools/faucet).

You can find the address of the owner key by running this command



```bash

cat keys/owner.addr

```



After requesting ada for the owner, send some ada to the beneficiary. The receiver address needs a small amount of ada

in order to provide it as collateral when unlocking the funds later.



```bash

python3 src/off_chain/distribute.py owner beneficiary 

```



Then you can place a vested amount of ada at the contract.

If you just requested funds for the owner address, you might need to wait a few minutes or the script will display an error that funds are missing.



```bash

python3 src/off_chain/make_vest.py owner beneficiary 

```



By default the deadline is 0 seconds after the creation of the vesting, so you can directly proceed and unlock

the vested amount with the beneficiary!



```bash

python3 src/off_chain/collect_vest.py beneficiary

```



That's it! You successfully compiled a Smart Contract on cardano and interacted with it through off-chain tooling.

Feel free to dive into the provided scripts and start customizing them for your needs.