Configure/optimize nginx for docker-based virtual services

Nginx is the SSL-terminator for multiple docker-based virtual services under a single-domain, sub-directory model. The relevant virtual services are GitLab and NextCloud; familiarity (basic administration) is not strictly necessarily but is a significant plus. Docker images for services: - [login to view URL] - [login to view URL] - nginx image negotiable, suggest from sameersbn, jwilder, or traefik Desired finished products: - [login to view URL] (that executes and serves correctly, minimal changes will be required for hostname and certificate locations); this is more for "proof-of-function" than actual deployment - [login to view URL] - other nginx "conf" files to support each virtual service (to go within "./sites-enabled/") Requirements: - nginx is run from neighboring docker image (this is negotiable) - services available via sub-directories: "https://host/gitlab/" and "https://host/nextcloud/" - nextcloud accessed via php-fpm; gitlab can use its own internal nginx server (note: not the gitlab omnibus) - nginx also serves a static-files location (e.g., a mounted docker volume) - real IP address and other appropriate proxy headers are passed to sub-services - no volume-sharing between nginx and gitlab/nextcloud - "standard" nginx logging (nothing specific, but not "no logging") Notes: - gitlab and nextcloud are not internally "https"; snake-oil certificates are fine for testing the nginx as an SSL-terminator - no access will be given to a physical server, all dev/testing is on the developer