Akropolis Gas Oracle

This service estimates EIP-1559 gas fees and legacy gas price. If the network supports EIP-1559, the estimates are based on the outputs of web3.getFeeHistory(200, 'pending', PERCENTILES), otherwise, gasPrice percentiles are calculated using transactions from the latest 200 blocks.

For Akropolis origins, the server can be reached at https://gas-oracle.akropolis.io/.

Supported networks

• Ethereum Mainnet 1
• BSC Mainnet 56
• Arbitrum One 42161
• Polygon 137

Installation

Clone this repo:

git clone git@github.com:akropolisio/gas-oracle.git
cd gas-oracle

Install dependencies:

npm install

Create .env with RPC urls:

cp .example.env .env && nano .env

Also make sure you have pm2 installed.

Usage

Start:

npm run start

Start with dev mode (will automatically refresh on source updates):

npm run start:dev

These commands will start separate pm2 processes for each network.

To stop pm2 run:

npm run stop

Note that pm2 runs in background, so to see console logs run:

pm2 logs

For more commands see pm2 docs.

Adding new networks

Add RPC url to .env:

JSON_RPC_URL_42="https://kovan.infura.io/v3/API_KEY"

Provide average block time (ms) in src/rpcSettings.json (default is 15000ms):

{
  "averageBlockTime": {
    // ...
    "42": 4000
  }
}

Restart pm2 in terminal:

pm2 restart pm2.json --update-env

API

The data can be fetched under [networkID] endpoint. The response contains a json with the following structure:

type GasParams = Record<
  'slow' | 'standard' | 'fast',
  {
    pendingBlock: number;
    gasPrice: number;
    waitTime: number;
    percent: number;
    baseFeePerGas?: number;
    maxPriorityFeePerGas?: number;
    maxFeePerGas?: number;
  }
>;

• pendingBlock - pending block number at the time of the request;
• gasPrice - suggested gasPrice in wei;
• waitTime - milliseconds to wait before tx is added in a block;
• percent - hardcoded values to calculate rewardPercentiles. Equal to 25 for slow speed, 60 for standard speed, and 90 for fast speed;
• baseFeePerGas - baseFeePerGas for the pending block in wei, undefined if EIP-1559 not supported;
• maxPriorityFeePerGas - suggested maxPriorityFeePerGas in wei, undefined if EIP-1559 not supported;
• maxFeePerGas - suggested maxFeePerGas in wei, undefined if EIP-1559 not supported. Equals to 2 * baseFeePerGas + maxPriorityFeePerGas.