npm package: @frinkly/ethereum-storage
Description: Request Network storage layer based on ethereum.
Latest version: 0.28.1

# @frinkly/ethereum-storage

`@frinkly/ethereum-storage` is a package part of the [Request Network protocol](https://github.com/RequestNetwork/requestNetwork).
It is an implementation of the Storage layer of Request Network protocol that uses IPFS to immutably store the data and uses the Ethereum network to persist the IPFS hash of the data and make them permanently available to everyone.

To use Infura to connect to an Ethereum node, get an infura token on [infura.io](infura.io) and
use as provider `"NETWORK_YOU_WANT.infura.io/v3/YOUR_INFURA_TOKEN"`.

## Installation

```bash
npm install @frinkly/ethereum-storage
```

## Usage

```js
import { EthereumStorage } from '@frinkly/ethereum-storage';
import { StorageTypes } from '@frinkly/types';

const web3HttpProvider = require('web3-providers-http');

const provider = new web3HttpProvider('http://localhost:8545');

const web3Connection: StorageTypes.IWeb3Connection = {
  networkId: StorageTypes.EthereumNetwork.PRIVATE,
  timeout: 1000,
  web3Provider: provider,
};

const ipfsGatewayConnection: StorageTypes.IIpfsGatewayConnection = {
  host: 'localhost',
  port: 5001,
  protocol: StorageTypes.IpfsGatewayProtocol.HTTP,
  timeout: 1000,
};

const ethereumStorage = new EthereumStorage(
  // Give an external url of the storage (use to indicate where the buffer data are stored)
  'url.buffer.ethereum.storage',
  ipfsGatewayConnection,
  web3Connection,
);

const data = 'Some data';

await ethereumStorage.append(data);
```

## Gas Limit

The gas limit defined as `safeGasPriceLimit` in [/src/config.ts](./src/config.ts) can be overridden with the environment variable `GAS_PRICE_DEFAULT`.

## Smart Contract

ethereum-storage uses smart contracts to store IPFS hashes.

The smart contracts can be downloaded in order to deploy them on a local environment:

```bash
git clone https://github.com/RequestNetwork/requestNetwork.git
cd requestNetwork/packages/smart-contracts
yarn install
yarn run build
yarn run ganache
```

And in another terminal:

```bash
yarn run deploy
```

There are 3 smart contracts:

- `RequestHashStorage` allows to declare a hash `NewHash(hash, submitter, feesParameters)`. Only a whitelisted contract can declare hashes.
- `RequestOpenHashSubmitter` entry point to add hashes in `RequestHashStorage`. It gives the rules to get the right to submit hashes and collect the fees. This contract must be whitelisted in `RequestHashStorage`. The only condition for adding hash is to pay the fees.
- `StorageFeeCollector` parent contract (not deployed) of `RequestOpenHashSubmitter`, computes the fees and send them to the burner.

#### Configuring the provider using Truffle and the development network

When deploying the smart contracts for development you can manually set the provider host and port via env variables:

```bash
TRUFFLE_GANACHE_HOST="host" TRUFFLE_GANACHE_PORT=1010 yarn run deploy
```

## IPFS

In order to use the package in a test environment, IPFS should be [installed locally](https://docs.ipfs.io/guides/guides/install/) and can then be started with the following commands:

```bash
yarn init-ipfs # documented below
ipfs daemon
```

Local IPFS listening on port 5001 is used by default by the `ethereum-storage` package.

### Setup IPFS private network

Request uses an IPFS private network to allow all nodes to connect to each other directly,
instead of having to navigate through the public IPFS network.

To setup your IPFS node to the private network, you can run the following utility script:

```bash
yarn init-ipfs
```

## Contributing

Pull requests are welcome. For major changes, please open an issue first to discuss what you would like to change.
[Read the contributing guide](/CONTRIBUTING.md)

## License

[MIT](/LICENSE)