truffle-config.js

/* global require module */

const HDWalletProvider = require('@truffle/hdwallet-provider');

const testMnemonic = 'test test test test test test test test test test test junk';

module.exports = {
  networks: {
    develop: {
      provider: function() {
        return new HDWalletProvider(testMnemonic, "http://127.0.0.1:9545/");
      },
      network_id: '1337',
    },
    dashboard: {
    },
  },
  mocha: {
    // timeout: 100000
  },
  plugins: [
    'truffle-plugin-stdjsonin'
  ],
  compilers: {
    solc: {
      version: "0.8.17", // Fetch exact version from solc-bin (default: truffle's version)
      // docker: true,        // Use "0.5.1" you've installed locally with docker (default: false)
       settings: {          // See the solidity docs for advice about optimization and evmVersion
         optimizer: {
           enabled: true,
           runs: 200
         },
         evmVersion: "berlin"
       }
    }
  }
};