API_URL is added to UI_URL if no schema provided

[nik123]

When I run install.sh without https/https part in API_URL variable, then API_URL is added to BACKEND_URL during authorization.

Environment:

1. Ubuntu 18.04.
2. docker-compose 1.28.2.
3. GitHub OAuth app.

How to reproduce:

1. Register your OAuth application on github according to instructions.
2. Login to private Iterative repository.
3. Run install script with command (IP address depends on your network configuration): UI_URL=192.168.1.33:3000 API_URL=192.168.1.33:8000/api GITHUB_CLIENT_ID=<client-id> GITHUB_SECRET_KEY=<secret-key> ./install.sh
4. Open http://192.168.1.33:3000 in you browser.
5. Click log in button.

Result:
You will get 404 error and for a moment there will be the following address in address bar of your browser: 192.168.1.33:3000/192.168.1.33:8000/api/login/github

Expected behavior:
Not sure, probably one of two options:

1. Do not allow UI_URL, API_URL without http/https part.
2. Somehow mention in the docs that if no http/https part provided, then API_URL is added to UI_URL.

[omesser]

This is abstracted away in our new supported installation method, using the studio helm chart (requires k8s). See: https://github.com/iterative/helm-charts
In the values structure, we take care of constructing the api/ui urls from given global.host to avoid host/url confusion
The docker-compose installation method is being phased out (still supported for existing customers until we reach out with a migration path).