knexfile-example.js

module.exports = {
  development: {
    client: 'postgresql',
    connection: {
      port: process.env.DATABASE_PORT,
      host: process.env.DATABASE_HOST,
      database: process.env.DATABASE_NAME,
      user: process.env.DATABASE_USER,
      password: process.env.DATABASE_ACCESS_KEY,
    },
    pool: {
      min: process.env.DATABASE_POOL_MIN,
      max: process.env.DATABASE_POOL_MAX,
    },
    migrations: {
      directory: './db/migrations',
      tableName: 'knex_migrations',
    },
    seeds: {
      directory: './db/seeds',
    },
  },

  staging: { ... },

  test: { ... },

  production: { ... },
}

@lucianodouglasm2 just require the file into knexjs config and pass the data.

const connection = require('./connection-data'); 

module.exports = {
  development: {
    client: 'postgresql',
    connection,
   ....
}