Nginx reverse proxy CORS fix

nginx.conf

#
# Run in the foreground locally
# nginx -p . -c nginx.conf
#
user  nginx;
worker_processes  auto;

error_log  /var/log/nginx/error.log notice;
pid        /var/run/nginx.pid;


events {
    worker_connections  1024;
}

http {
    include       /etc/nginx/mime.types;
    default_type  application/octet-stream;

    log_format  main  '$remote_addr - $remote_user [$time_local] "$request" '
                      '$status $body_bytes_sent "$http_referer" '
                      '"$http_user_agent" "$http_x_forwarded_for"';

    access_log  /var/log/nginx/access.log  main;

    sendfile        on;
    #tcp_nopush     on;

    keepalive_timeout  65;

    #gzip  on;

    # include /etc/nginx/conf.d/*.conf;


    server {
        listen 8060;


        location /score {
            proxy_pass  http://host.docker.internal:6789/score;

            include cors_support;
        }
    }
}


# Con un fichero cors_support con el siguiente contenido:
#
# As of Nginx 1.7.5, add_header supports an "always" parameter which
# allows CORS to work if the backend returns 4xx or 5xx status code.
#
# For more information on CORS, please see: http://enable-cors.org/
# Forked from this Gist: https://gist.github.com/michiel/1064640
#

set $cors '';

#if ($http_origin ~ '^http?://(localhost|www\.yourdomain\.com|www\.yourotherdomain\.com)') {
#        set $cors 'true';
#}

set $cors 'true';


if ($cors = 'true') {
        add_header 'Access-Control-Allow-Origin' "$http_origin" always;
        #add_header 'Access-Control-Allow-Origin' * always;
        add_header 'Access-Control-Allow-Credentials' 'true' always;
        add_header 'Access-Control-Allow-Methods' 'GET, POST, PUT, DELETE, OPTIONS' always;
        add_header 'Access-Control-Allow-Headers' 'Accept,Authorization,Cache-Control,Content-Type,DNT,If-Modified-Since,Keep-Alive,Origin,User-Agent,X-Requested-With' always;
        # required to be able to read Authorization header in frontend
        add_header 'Access-Control-Expose-Headers' 'Authorization' always;
}

if ($request_method = 'OPTIONS') {
        # Tell client that this pre-flight info is valid for 20 days
        add_header 'Access-Control-Allow-Origin' "$http_origin" always;
        add_header 'Access-Control-Allow-Headers' 'Accept,Authorization,Cache-Control,Content-Type,DNT,If-Modified-Since,Keep-Alive,Origin,User-Agent,X-Requested-With' always;
        add_header 'Access-Control-Max-Age' 1728000;
        add_header 'Content-Type' 'text/plain charset=UTF-8';
        add_header 'Content-Length' 0;
        return 204;
}

docker run --name nginx-proxy4 -p 127.0.0.1:8060:8060 -v /home/acg/nginx.conf:/etc/nginx/nginx.conf:ro -v /home/acg/cors_support:/etc/nginx/cors_support -d nginx