There are many posts on SO and elsewhere on how to set this up. So far I've been unsuccessful in getting it working.

Setup
Local machine - Windows 10, with Cygwin, git bash, and WSL2 with Ubuntu installed; and MacBook Air (Mojave)
Host machine - AWS EC2 instance running Amazon Linux 2
Docker container - CentOS 7.8 running PHP with Xdebug

Goal
Remotely debug PHP code in container from local machine by utilizing a reverse tunnel from the local machine to the container.

I have gotten this working before when the PHP code was installed locally on the host machine, so the question is not around Xdebug. As soon as I moved the PHP code into the container, debugging no longer works.

What I've tried
Setting up a reverse tunnel from the local machine to the host EC2 instance works. For this I'm doing ssh -vvv -i "aws.pem" -R 9000:localhost:9000 user@ec2instance in terminal, cygwin, or git bash and testing with nc -z localhost 9000 || echo 'no tunnel open' on the host machine.

When I docker exec -it container bash into the container and run nc, the tunnel is not available.

I'm using docker-compose:

version: '2'
services:
  web:
    image: 'privateregistry/project/container:latest'
    restart: always
    container_name: web
    ports:
      - '8082:80'
      - '447:443'
      - '9000:9000'
    volumes:
      - '.:/var/www/project'

I have tried with and without mapping the 9000 port. I have tried variations of the ssh tunnel:

ssh -vvv -i "aws.pem" -R :9000:localhost:9000 user@ec2instance
ssh -vvv -i "aws.pem" -R 0.0.0.0:9000:localhost:9000 user@ec2instance
ssh -vvv -i "aws.pem" -R \*:9000:localhost:9000 user@ec2instance
ssh -vvv -i "aws.pem" -R 9000:172.20.0.2:9000 user@ec2instance (container IP)

I've also tried using ssh -L with no luck.

Several posts, like this one suggest adding GatewayPorts yes on the host machine. I've tried this as well with no change.

I have not tried using --network=host, primarily due to security concerns. I also would rather not use ngrok, as I'd like to be able to use localhost or host.docker.internal for the xdebug.remote_host setting.

For completeness, here is what I have for Xdebug:

[XDebug]
xdebug.remote_enable=1
xdebug.remote_autostart=1
xdebug.remote_handler="dbgp"
xdebug.remote_port=9000
xdebug.remote_host="host.docker.internal"
;xdebug.remote_connect_back=1
xdebug.idekey = VSCODE
xdebug.remote_log = "/var/log/xdebug.log"