if you don't have the fitting Dockerfile + docker-compose.yml your installation might end in troubles
I'd suggest using one of the ready-made templates.
https://github.com/intersystems-community/objectscript-docker-template

or any other from OEX https://openexchange.intersystems.com/

As by default is READ ONLY as with any installation and you are well-advised not to change this.
What container image do you start ?

@Sergei Shutov     You missed the point.
validator
is typically stored as part of the individual data record to handle various types of checks within your class to provide the highest flexibility. Think of language or geographically related checking.

You can't bypass the challenge.
Neither by $classmetho() nor any code generator as this is all static code frozen and inflexible a runtime. 

Creating a check routine by field or by record is not a realistic solution