Adding Mailhog to Docker-compose and enabling in WordPress

docker-compose.yml

version: '3'

services:
   db:
     image: mysql:5.7
     volumes:
       - db_data:/var/lib/mysql
     restart: always
     environment:
       MYSQL_ROOT_PASSWORD: somewordpress
       MYSQL_DATABASE: wordpress
       MYSQL_USER: wordpress
       MYSQL_PASSWORD: wordpress

   wordpress:
     depends_on:
       - db
     image: wordpress:latest
     ports:
       - "8000:80"
     restart: always
     environment:
       WORDPRESS_DB_HOST: db:3306
       WORDPRESS_DB_USER: wordpress
       WORDPRESS_DB_PASSWORD: wordpress

  mailhog:
  image: mailhog/mailhog
  ports: 
    - 1025:1025 # smtp server
    - 8025:8025 # web ui

volumes:
    db_data:

functions.php

<?php
add_action( 'phpmailer_init', 'setup' );
function setup( PHPMailer $phpmailer ) {
    $phpmailer->Host = 'mailhog';
    $phpmailer->Port = 1025;
    $phpmailer->IsSMTP();
}