nginx.conf file, included from another http context

a.conf

# Based on:
# https://www.netguru.co/codestories/nginx-tutorial-performance
# https://www.netguru.co/codestories/nginx-tutorial-ssl-setup
# https://www.digitalocean.com/community/tutorials/understanding-nginx-http-proxying-load-balancing-buffering-and-caching

gzip on;               # enable gzip
gzip_http_version 1.1; # turn on gzip for http 1.1 and higher
gzip_disable "msie6";  # IE 6 had issues with gzip
gzip_comp_level 5;     # inc compresion level, and CPU usage
gzip_min_length 256;   # minimal weight to gzip file (files below this in bytes are not compressed)
gzip_proxied any;      # enable gzip for proxied requests (e.g. CDN)
gzip_buffers 16 8k;    # compression buffers (if we exceed this value, disk will be used instead of RAM)
gzip_vary on;          # add header Vary Accept-Encoding

# define files which should be compressed
gzip_types text/plain;
gzip_types text/css;
gzip_types application/javascript;
gzip_types application/json;
gzip_types application/manifest+json;
gzip_types image/svg+xml;
gzip_types image/x-icon;

  tcp_nodelay on;     # sets TCP_NODELAY flag, used on keepalive connections

  ssl on;
  ssl_certificate     /etc/ssl/certs/cert.pem;
  ssl_certificate_key /etc/ssl/certs/key.pem;
  # security
  ssl_protocols TLSv1 TLSv1.1 TLSv1.2;
  ssl_ciphers EECDH+CHACHA20:EECDH+AES128:RSA+AES128:EECDH+AES256:RSA+AES256:!MD5;
  ssl_prefer_server_ciphers on;
  # performance
  ssl_session_cache   shared:SSL:5m; # One megabyte of the cache contains about 4000 sessions
  ssl_session_timeout 10m;

  server_tokens off;


  #=============#
  # RESTFUL API #
  #=============#
  server {
      listen 443 ssl;
      listen [::]:443 ssl;
      server_name  api.dev.local;

      # # general configs
      # keepalive_timeout    20;
      # listen               127.0.0.1:443 ssl;
      # server_name          api.example.com;

      # # ssl configs
      # ssl_certificate      /path/to/api.crt;
      # ssl_certificate_key  /path/to/api.key;
      # ssl_session_cache    shared:SSL:10m;
      # ssl_session_timeout  10m;

      # # logs paths
      # access_log false;
      # error_log  /path/to/error.log crit;

      proxy_set_header X-Real-IP $remote_addr;
      proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
      proxy_set_header Host $host;

      location / {
        proxy_pass                http://restful_api:3000;
        proxy_http_version        1.1;

        # handle OPTIONS requests
        # @note: don't try to DRY out this "if" block, or you're gonna have a bad time.
        # @see: http://wiki.nginx.org/IfIsEvil
        if ($request_method = 'OPTIONS') {
          add_header 'Access-Control-Allow-Credentials' 'true';
          add_header 'Access-Control-Allow-Headers'     'Authorization,Content-Type,Accept,Origin,User-Agent,DNT,Cache-Control,Keep-Alive,X-Requested-With,If-Modified-Since';
          add_header 'Access-Control-Allow-Methods'     'GET, DELETE, OPTIONS, POST, PUT';
          add_header 'Access-Control-Allow-Origin'      'https://app.dev.local';
          add_header 'Access-Control-Max-Age'           2592000;
          add_header 'Content-Length'                   0;
          # add_header 'Content-Type'                     'text/plain charset=UTF-8';
          return 204;
        }

        # proxy to the nodejs application
        # client_max_body_size 64G;

        # send the CORS headers
        add_header 'Access-Control-Allow-Credentials' 'true';
        add_header 'Access-Control-Allow-Origin'      'https://app.dev.local';

        # set additional security headers
        add_header 'Cache-Control'                    'no-cache, no-store, must-revalidate';
        # add_header 'Content-Security-Policy'          'connect-src example.com';
        # add_header 'Expires'                          '0';
        # add_header 'Pragma'                           'no-cache';
        # add_header 'Strict-Transport-Security'        'max-age=31536000; includeSubDomains';
        add_header 'X-Content-Type-Options'           'nosniff';
        add_header 'X-Frame-Options'                  'DENY';
        add_header 'X-XSS-Protection'                 '1; mode=block';
      }
  }

  #=================#
  # SINGLE PAGE APP #
  #=================#
  server {
      listen 443 ssl default_server;
      listen [::]:443 ssl default_server;
      server_name  app.dev.local;
      root  /var/www/app/;

      tcp_nopush on;

      location / {
        index index.html =404;
      }

      # location ~* \.(jpg|jpeg|png|gif|ico|css|js)$ {
      #   expires 1M;
      #   add_header Cache-Control  public;
      #   add_header Pragma         public;
      #   add_header Vary           Accept-Encoding;
      # }

      location /api {
        # can't set the proxy yet cuz i fail :(proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header Host something.appspot.com;
        proxy_set_header X-NginX-Proxy true;
        proxy_pass https://res/;
        proxy_ssl_session_reuse off;
        proxy_redirect off;
      }

      # PWA related location, do I need this?
      location /manifest.json {
          default_type application/x-web-app-manifest+json;
      }

  }

# Not working
# # Rewrite all trafic on port 80 to 443
# server {
#   listen         80;
#   server_name    api.dev.local;
#   rewrite        ^ https://$server_name:8000$request_uri? permanent;
# }


  #=======================================#
  # Scaling with upstream pool of servers #
  #=======================================#
  # upstream backend_hosts {
  #     least_conn; # balancing algorythm

  #     server host1.example.com;
  #     server host2.example.com;
  #     server host3.example.com;
  # }

  # server {
  #     listen 80;
  #     server_name example.com;

  #     location /proxy-me {
  #         proxy_pass http://backend_hosts;
  #     }
  # }

server {
    listen 80 ssl default_server;
    listen [::]:80 ssl default_server;
    server_name *.dev.local dev.local;


      if ($http_x_forwarded_proto != "https") {
        return 301 https://$host$request_uri;
      }
    return 301 https://$host$request_uri;
}