Trying to Get SSL Up with Docker Nginx and Certbot - docker

Question

I have hit this roadblock where I am not able get the SSL Certificates from Let's encrypt.
I am using Nginx , Certbot and trying to get SSL running for my site with a node backend.
I tried to follow this post as my knowledge is limited. Any help pointers would be highly appreciated.
https://medium.com/#pentacent/nginx-and-lets-encrypt-with-docker-in-less-than-5-minutes-b4b8a60d3a71
As the post mentions , I first try to run the script to get a dummy certificate. I have modified the script to point to my domain.
But I get this error
Failed authorization procedure. example.org (http-01):
urn:ietf:params:acme:error:connection :: The server could not connect
to the client to verify the domain :: Fetching
http://example.org/.well-known/acme-challenge/Jca_rbXSDHEmXz8-y3bKKckD8g0lsuoQJgAxeSEz5Jo:
Connection refused
IMPORTANT NOTES:
- The following errors were reported by the server:
Domain: example.org Type: connection Detail: Fetching
http://example.org/.well-known/acme-challenge/Jca_rbXSDHEmXz8-y3bKKckD8g0lsuoQJgAxeSEz5Jo:
Connection refused
This is my nginx configuration
upstream app {
server app:3000;
}
server {
listen 80;
server_name example.org;
location / {
proxy_pass http://app/;
}
location /.well-known/acme-challenge/ {
root /var/www/certbot;
}
# location /api/ {
# proxy_pass http://app/;
# proxy_redirect off;
# proxy_set_header Host $host;
# 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;
# }
}
server {
listen 443 ssl;
server_name example.org;
ssl_certificate /etc/letsencrypt/live/example.org/fullchain.pem;
ssl_certificate_key /etc/letsencrypt/live/example.org/privkey.pem;
include /etc/letsencrypt/options-ssl-nginx.conf;
ssl_dhparam /etc/letsencrypt/ssl-dhparams.pem;
location / {
proxy_pass http://example.org; #for demo purposes
}
}