How to get an SSL certificate in Docker compose?

Question

I am trying to configure my docker-compose with nginx and certbot to get an SSL certificate. I am doing everything as this repo says: https://github.com/wmnnd/nginx-certbot

docker-compose.yml:

version: '3'

services:
  nginx:
    image: nginx:1.15-alpine
    restart: unless-stopped
    volumes:
      - ./data/nginx:/etc/nginx/conf.d
      - ./data/certbot/conf:/etc/letsencrypt
      - ./data/certbot/www:/var/www/certbot
    ports:
      - "80:80"
      - "443:443"
    command: "/bin/sh -c 'while :; do sleep 6h & wait $${!}; nginx -s reload; done & nginx -g \"daemon off;\"'"
  certbot:
    image: certbot/certbot
    restart: unless-stopped
    volumes:
      - ./data/certbot/conf:/etc/letsencrypt
      - ./data/certbot/www:/var/www/certbot
    entrypoint: "/bin/sh -c 'trap exit TERM; while :; do certbot renew; sleep 12h & wait $${!}; done;'"

app.conf:

server {
    listen 80;
    server_name rusinas.wtf;
    server_tokens off;

    location /.well-known/acme-challenge/ {
        root /var/www/certbot;
    }

    location / {
        return 301 https://$host$request_uri;
    }
}

server {
    listen 443 ssl;
    server_name rusinas.wtf;
    server_tokens off;

    ssl_certificate /etc/letsencrypt/live/rusinas.wtf/fullchain.pem;
    ssl_certificate_key /etc/letsencrypt/live/rusinas.wtf/privkey.pem;
    include /etc/letsencrypt/options-ssl-nginx.conf;
    ssl_dhparam /etc/letsencrypt/ssl-dhparams.pem;

    location / {
        proxy_pass  http://rusinas.wtf;
        proxy_set_header    Host                $http_host;
        proxy_set_header    X-Real-IP           $remote_addr;
        proxy_set_header    X-Forwarded-For     $proxy_add_x_forwarded_for;
    }
}

Then I need to run this .sh script:

#!/bin/bash

if ! [ -x "$(command -v docker-compose)" ]; then
  echo 'Error: docker-compose is not installed.' >&2
  exit 1
fi

domains=(rusinas.wtf www.rusinas.wtf)
rsa_key_size=4096
data_path="./data/certbot"
email="[email protected]" # Adding a valid address is strongly recommended
staging=1 # Set to 1 if you're testing your setup to avoid hitting request limits

if [ -d "$data_path" ]; then
  read -p "Existing data found for $domains. Continue and replace existing certificate? (y/N) " decision
  if [ "$decision" != "Y" ] && [ "$decision" != "y" ]; then
    exit
  fi
fi


if [ ! -e "$data_path/conf/options-ssl-nginx.conf" ] || [ ! -e "$data_path/conf/ssl-dhparams.pem" ]; then
  echo "### Downloading recommended TLS parameters ..."
  mkdir -p "$data_path/conf"
  curl -s https://raw.githubusercontent.com/certbot/certbot/master/certbot-nginx/certbot_nginx/_internal/tls_configs/options-ssl-nginx.conf > "$data_path/conf/options-ssl-nginx.conf"
  curl -s https://raw.githubusercontent.com/certbot/certbot/master/certbot/certbot/ssl-dhparams.pem > "$data_path/conf/ssl-dhparams.pem"
  echo
fi

echo "### Creating dummy certificate for $domains ..."
path="/etc/letsencrypt/live/$domains"
mkdir -p "$data_path/conf/live/$domains"
docker-compose run --rm --entrypoint "\
  openssl req -x509 -nodes -newkey rsa:$rsa_key_size -days 1\
    -keyout '$path/privkey.pem' \
    -out '$path/fullchain.pem' \
    -subj '/CN=localhost'" certbot
echo


echo "### Starting nginx ..."
docker-compose up --force-recreate -d nginx
echo

echo "### Deleting dummy certificate for $domains ..."
docker-compose run --rm --entrypoint "\
  rm -Rf /etc/letsencrypt/live/$domains && \
  rm -Rf /etc/letsencrypt/archive/$domains && \
  rm -Rf /etc/letsencrypt/renewal/$domains.conf" certbot
echo


echo "### Requesting Let's Encrypt certificate for $domains ..."
#Join $domains to -d args
domain_args=""
for domain in "${domains[@]}"; do
  domain_args="$domain_args -d $domain"
done

# Select appropriate email arg
case "$email" in
  "") email_arg="--register-unsafely-without-email" ;;
  *) email_arg="--email $email" ;;
esac

# Enable staging mode if needed
if [ $staging != "0" ]; then staging_arg="--staging"; fi

docker-compose run --rm --entrypoint "\
  certbot certonly --webroot -w /var/www/certbot \
    $staging_arg \
    $email_arg \
    $domain_args \
    --rsa-key-size $rsa_key_size \
    --agree-tos \
    --force-renewal" certbot
echo

echo "### Reloading nginx ..."
docker-compose exec nginx nginx -s reload

But I am getting the error:

Certbot failed to authenticate some domains (authenticator: webroot). The Certificate Authority reported these problems:     
  Domain: rusinas.wtf
  Type:   connection
  Detail: 165.227.153.70: Fetching http://rusinas.wtf/.well-known/acme-challenge/qSn6ROSM6PAtyzbaJoWhQl-9qbApbCkJ95tX-z_FLc4: Connection refused

  Domain: www.rusinas.wtf
  Type:   connection
  Detail: 165.227.153.70: Fetching http://www.rusinas.wtf/.well-known/acme-challenge/zDltta9WYRq1xEo3M7HhxkSX-xjC1XvWcMPx4-CHu8Y: Connection refused

Hint: The Certificate Authority failed to download the temporary challenge files created by Certbot. Ensure that the listed domains serve their content from the provided --webroot-path/-w and that files created there can be downloaded from the internet.

I have no idea how to fix it. It is quite obvious that my domain should be available in order to certbot to confirm it, buut I can't see how it is possible. I tried to run all this on my VPS but no success, my website is not available, even though the nginx container is running just fine. I guess the problem is in the configuration, but I am no expert in this area :(