Excerpts from my nginx config which helped me to skip CORS issue where cross origin requests are not allowed

nginx.conf for CORS

server {
# Nginx listens at this address, http://172.17.0.1:4321
        listen       4321;
        server_name  172.17.0.1;

# Nginx listens to this location when calls are made to http://172.17.0.1:4321/location1
location ~ /location1 {
    # we could have set any server here, lets call this server 1.
    proxy_pass http://172.17.0.1:1234;
    # add a header for host, keep it same all across
    proxy_set_header Host "172.17.0.1:4321";
    add_header 'Access-Control-Allow-Origin' '*';
    proxy_http_version 1.1;
    proxy_redirect     off;
    proxy_set_header Connection "";

    access_log /var/log/nginx/some-random-logfile1.log;
}

# Nginx listens to this location when calls are made to http://172.17.0.1:4321/location2
location ~ /location2 {
    # we could have set any server here, lets call this server 2.
    proxy_pass http://172.17.0.1:3000;
    # add a header for host, keep it same all across
    proxy_set_header Host "172.17.0.1:4321";
    add_header 'Access-Control-Allow-Origin' '*';
    proxy_http_version 1.1;
    proxy_redirect     off;
    proxy_set_header Connection "";

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

    access_log /var/log/nginx/some-random-logfile2.log;


    # cors headers

    if ($request_method = 'OPTIONS') {
        add_header 'Access-Control-Allow-Origin' '*';
        add_header 'Access-Control-Allow-Credentials' 'true';
        add_header 'Access-Control-Allow-Methods' 'GET, POST, OPTIONS';
        add_header 'Access-Control-Allow-Headers' 'DNT,X-CustomHeader,Keep-Alive,User-Agent,X-Requested-With,If-Modified-Since,Cache-Control,Content-Type';
        add_header 'Access-Control-Max-Age' 1728000;
        add_header 'Content-Type' 'text/plain charset=UTF-8';
        add_header 'Content-Length' 0;
        return 204;
    }
    if ($request_method = 'POST') {
        add_header 'Access-Control-Allow-Origin' '*';
        add_header 'Access-Control-Allow-Credentials' 'true';
        add_header 'Access-Control-Allow-Methods' 'GET, POST, OPTIONS';
        add_header 'Access-Control-Allow-Headers' 'DNT,X-CustomHeader,Keep-Alive,User-Agent,X-Requested-With,If-Modified-Since,Cache-Control,Content-Type';
    }
    if ($request_method = 'GET') {
        add_header 'Access-Control-Allow-Origin' '*';
        add_header 'Access-Control-Allow-Credentials' 'true';
        add_header 'Access-Control-Allow-Methods' 'GET, POST, OPTIONS';
        add_header 'Access-Control-Allow-Headers' 'DNT,X-CustomHeader,Keep-Alive,User-Agent,X-Requested-With,If-Modified-Since,Cache-Control,Content-Type';
    }
}
}