Nginx not listening on new ports with systemctl reload nginx after adding config with a new port

Not sure how to quickly summary this issue, so I will put my scenario in bulletpoints:

• Normal basic nginx install
• I only use https(443), so I removed all http(80) config
• When you start nginx (or restart it), the process seems to listen on port 80 as well (ss -tulp)
• When I add a config in /etc/nginx/sites-enabled with a listener on http(80) and then;
• Reload nginx, using systemctl reload nginx (note: reload, not restart)
• It does not work, as if nginx is still not listening for traffic on port 80
• If I run systemctl restart nginx it does work.

I noticed this, because LetsEncrypt couldn't renew my certificates. After investigating the issue, I noticed the behaviour described above.
Because I had no nginx config listening on http(80), I think nginx just doesn't add any listeners or something when I start nginx (although port 80 was claimed by nginx)
And if Certbot then tries to renew my certificates, it would add a temporary http(80) config to the nginx config directory, presumably followed by a "reload" of nginx, rather than a restart (which is as expected and as it should)
But since nginx was started without http(80) config, it didn't process the traffic from LetsEncrypt to that temporary challenge config.
My solution was quite simple, to add a basic http(80) config block to nginx with only a return 404; and restarted nginx. After that, Certbot worked just fine and could renew all my certificates.

I was wondering if this is expected behaviour, or if this is a (known) bug in Nginx.

Thanks

Update:

nginx version: nginx/1.18.0
Debian 11 (Bullseye)

I don't think this is a bug, I think this is something wrong at your end. I can't recreate your issue.

I've spun up a fresh EC2 instance with Amazon Linux and installed nginx.

Commented out http server, uncommented https, and generated certs:

#    server {
#        listen       80;
#        listen       [::]:80;
#        server_name  _;
#        root         /usr/share/nginx/html;
#
#        # Load configuration files for the default server block.
#        include /etc/nginx/default.d/*.conf;
#
#        error_page 404 /404.html;
#        location = /404.html {
#        }
#
#        error_page 500 502 503 504 /50x.html;
#        location = /50x.html {
#        }
#    }

    server {
        listen       443 ssl http2;
        listen       [::]:443 ssl http2;
        server_name  _;
        root         /usr/share/nginx/html;

        ssl_certificate "/etc/pki/nginx/cert.pem";
        ssl_certificate_key "/etc/pki/nginx/key.pem";
        ssl_session_cache shared:SSL:1m;
        ssl_session_timeout  10m;
        # ssl_ciphers PROFILE=SYSTEM;
        # ssl_prefer_server_ciphers on;

        # Load configuration files for the default server block.
        include /etc/nginx/default.d/*.conf;

        error_page 404 /404.html;
            location = /40x.html {
        }

        error_page 500 502 503 504 /50x.html;
            location = /50x.html {
        }
    }

Certs:

[root@ip-10-0-0-110 nginx]# ls -l /etc/pki/nginx/
total 8
-rw-r--r-- 1 nginx nginx 2155 Feb  4 09:28 cert.pem
-rw-r--r-- 1 nginx nginx 3272 Feb  4 09:28 key.pem

Start up the server, and port 80 is not in use, but 443 is:

[root@ip-10-0-0-110 nginx]# ss -plunt | grep ':80'
[root@ip-10-0-0-110 nginx]# ss -plunt | grep ':443'
tcp  LISTEN 0      511                            0.0.0.0:443       0.0.0.0:*    users:(("nginx",pid=32264,fd=6),("nginx",pid=32262,fd=6),("nginx",pid=32205,fd=6))
tcp  LISTEN 0      511                               [::]:443          [::]:*    users:(("nginx",pid=32264,fd=7),("nginx",pid=32262,fd=7),("nginx",pid=32205,fd=7))

Uncomment HTTP and do a systemctl reload nginx, and both are in use:

[root@ip-10-0-0-110 nginx]# vim /etc/nginx/nginx.conf
[root@ip-10-0-0-110 nginx]# systemctl reload nginx
[root@ip-10-0-0-110 nginx]# ss -plunt | grep ':443'
tcp  LISTEN 0      511                            0.0.0.0:443       0.0.0.0:*    users:(("nginx",pid=32288,fd=6),("nginx",pid=32287,fd=6),("nginx",pid=32205,fd=6))
tcp  LISTEN 0      511                               [::]:443          [::]:*    users:(("nginx",pid=32288,fd=7),("nginx",pid=32287,fd=7),("nginx",pid=32205,fd=7))
[root@ip-10-0-0-110 nginx]# ss -plunt | grep ':80'
tcp  LISTEN 0      511                            0.0.0.0:80        0.0.0.0:*    users:(("nginx",pid=32288,fd=13),("nginx",pid=32287,fd=13),("nginx",pid=32205,fd=13))
tcp  LISTEN 0      511                               [::]:80           [::]:*    users:(("nginx",pid=32288,fd=14),("nginx",pid=32287,fd=14),("nginx",pid=32205,fd=14))
[root@ip-10-0-0-110 nginx]#

Comment it out and reload again, only 443 is listening.

Version installed:

[root@ip-10-0-0-110 nginx]# yum list nginx
Loaded plugins: extras_suggestions, langpacks, priorities, update-motd
Installed Packages
nginx.x86_64                               1:1.20.0-2.amzn2.0.4