host.conf

server {
    # We're behind a reverse proxy so we only listen on port 80.
    listen 80;
    resolver 127.0.0.11; # helps it resolve "mapproxy" which is a docker

    location /500 {
        return 500;
    }

    ### precincts

    # Static content for precinct PDF documents, see also both volume entries... precinct PDFs and precinct thumbnails
    # Since the precinct docs are PDFs I don't have a convenient way
    # to generate them on the fly yet.
    location /precincts/ {
    root /srv;
    autoindex on;
    }
    location /precinct_tn/ {
    root /srv;
    autoindex on;
    }
    # Perhaps I should update the popup code to use this instead
    #location /precincts/tn/ {
    #  root /srv;
    #  autoindex on;
    #}

    #### bridges and waterways

    # Rewriting URLS to change simple IDs into complete URLs.
    # In your app, you can use either the plain ID from the attribute field
    # or the complete photo filename (see next section), it does not matter.

    # All bridge photos have a number (3 or 4 digit) followed by a single uppercase letter
    location ~ \/photos\/(tn\/)?bridges/(\d+[A-Z])$ {
        # either of these returns works, the second is simpler
#        return 301 https://$host/photos/$1bridges/$2.jpg;
        return 301 https://$host$request_uri.jpg;
    }

    # All waterway photos have a number only
    location ~ \/photos\/(tn\/)?waterway\/(\d+)$ {
        return 301 https://$host/photos/$1waterway/ph$2.png;
    }

    # Serve the actual bridges/ and waterway/ photos (full names) here.

    location /photos {
        alias /srv/img;
        error_page 404 415 =200 /photos/static/no_photo_available.png;
    }
    # Generate thumbnails on the fly.
    location /photos/tn {
        alias /srv/img; # Serve the same images, but shrink them
        image_filter resize 220 150;
        image_filter_buffer 100m; # Avoid "too big" errors.

        error_page 404 415 =200 /photos/static/no_photo_available.png;
    }

    # All other static content is here, including the "no photo" image.
    # It's a volume, so no restart should be needed.
    location /photos/static {
        alias /srv/static;
        autoindex on;
    }

### mapproxy -- everything else...

    location / {
        # This fails because "mapproxy" only resolves internally.
        #return 301 http://mapproxy:8080$request_uri;
        # This works because traffic passes through this nginx.
        proxy_pass http://mapproxy:8080;
        proxy_set_header Host $http_host;
        proxy_set_header X-Real-IP $remote_addr;
        #proxy_set_header X-Script-Name "/mapproxy";

#        error_page 404 415 =200 /photos/static/no_photo_available.png;
    }
}