code for Knex connection establish with postgres.

knexAdapter.js

const pg = require('pg');
const knexConfig = {
 client: 'pg',
 connection: {
    host : process.env.SQL_HOST,
    database: process.env.SQL_DB,
    user: process.env.SQL_USERNAME,
    password: process.env.SQL_PASSWORD,
 }
};
module.exports = require('knex')(knexConfig);