Create environment files (cf. `git ls-files \*environment.template`):
* Set SA_PUBLIC_DOMAIN_NAME in `environment`
* Set CANONICAL_WEB_URL in `gerrit/environment`
* Enable GitHub OAUTH in `gerrit/environment`

To build:
* nginx first because it creates selfsigned certificate `docker-compose build nginx`
* then everything else `docker-compose build`

Get containers up:
* `docker-compose up`