To build:
* nginx first because it creates selfsigned certificate:
  docker-compose -f sourcearcade.yml build --build-arg SELFSIGNED_REQ_HOST=hostname nginx
  - optionally: --build-arg SELFSIGNED_REQ_ALT_NAMES="DNS:name1 ..."
* docker-compose -f sourcearcade.yml build --build-arg SELFSIGNED_REQ_HOST=hostname
  - same build-args!

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`