Legacy LAMP Stack on Docker - php

Question

I want to preface this by saying this question is more about system design and is somewhat open-ended. There isn't anything, in particular, I need help with. But I would appreciate some guidance. I will provide a copy of my docker-compose.yml so it's easier to visualize what I'm working with.
I'm looking to dockerize an older LAMP stack application. This app is currently deployed in a CentOS 6.10 VM, running PHP 5.4, MySQL 5.7, and Apache 2.2.15.
I wonder how I might go about dockerizing while minimizing the number of modifications I have to make to the underlying codebase.
I was playing with aliasing deprecated functions and redefining them with an updated API, but, it's been quite the hassle. Here's an example:
if (!function_exists('mysql_num_rows')) {
function mysql_num_rows($result)
{
return mysqli_num_rows($result);
}
}
Here's my docker-compose.yml:
version: "3.8"
x-common-variables: &common-variables
MYSQL_ROOT_PASSWORD: root
MYSQL_USER: ...
MYSQL_PASSWORD: ...
volumes:
mysql:
driver: local
services:
mysql:
platform: linux/x86_64
image: mysql:5.7
container_name: mysql_container
environment:
<<: *common-variables
ports:
- 3306:3306
restart: unless-stopped
volumes:
- mysql:/var/lib/mysql
- ./docker/init.sql:/docker-entrypoint-initdb.d/init.sql
phpmyadmin:
depends_on:
- mysql
image: phpmyadmin:latest
container_name: phpadmin_container
environment:
<<: *common-variables
PMA_HOST: mysql
links:
- mysql:mysql
ports:
- 8080:81
restart: always
apache:
container_name: apache_container
depends_on:
- mysql
build: ./bootstrap
environment:
<<: *common-variables
extra_hosts:
- "app1.localhost.com:127.0.0.1" # This is configured in local hosts file
- "app2.localhost.com:127.0.0.1"
ports:
- 443:443 # App requires SSL - using a self-signed cert locally
- 80:80
volumes:
- ./bootstrap/httpd.conf:/etc/apache2/sites-enabled/000-default.conf
- ./bootstrap/php.ini:/usr/local/etc/php/php.ini
- ./:/var/www
links:
- mysql:mysql
I'm using the php:7.4-apache image for the apache service (not shown here, it's in the Dockerfile).
As I was writing this question, I realized I could probably use a centos image and install the older versions of software required for the project. However, I'm still going to post because any insight would be helpful.
Let me know if there's any more info I can provide!