Allow direct port expose of MySQL

[AdrianPop]

Description of problem

I have a small app which needs to have the DB on a different host than the code. Due to this, I've installed dokku-mysql on host A and the backend app on host B.
The problem is with the expose command which is done through ambassador or socat. This is painfully slow. I mean a page which would load in 300ms, loads in 4-5s if using expose.

Due to this I've searched for ways to replace socat and ended up digging through bash commands

How reproducible

Steps to Reproduce

1. dokku mysql:create db - all ports are closed
2. dok mysql:create db --shm-size "64mb -p 9089:3306" - port 3306 is mapped to 9089

Actual Results

• all ports are closed

Expected Results

• some ports open

Additional information

• Somehow I'm using "bash injection" (like sql injection). The $SHM_SIZE param from here is the only param that comes unaltered. And I'm adding the default shm-size for docker and add extra params for docker run command.

Open discussion

I think by using socat, there's no protection level compared to a simple port-expose.
If you agree that this would be a nice feature, I could create a PR.
My solution would be:

• add in --create-flags another option to be provided to docker run like -d|--docker-options with free text. This way I can decide to use -P or --port 1234:3306 or simply add any other docker run options there.

What do you think?