nginx in docker 502

I have a Docker Registry in a container on my server. My NginX is also in a container and another location(config) for static files works. So i can confirm that ssl is propperly configured. Curl on the server to the docker registry also works, so i can confirm that my registry is hosted correctly. (Linux reports it listening onto http://*:5000).

as far as i know i did everything right, but it somehow still doesnt work. here the 2 error messages i get:

2024/09/21 18:14:50 [error] 19#19: *34 no live upstreams while connecting to upstream, client: IP, server: docker.myDomain.org, request: "GET /v2/ HTTP/1.1", upstream: "http://localhost/v2/", host: "docker.myDomain.org"
2024/09/21 18:15:17 [error] 19#19: *35 connect() failed (111: Connection refused) while connecting to upstream, client: IP, server: docker.myDomain.org, request: "GET /.git/config HTTP/1.1", upstream: "http://127.0.0.1:5000/.git/config", host: "213.165.94.168"

my Config 'docker.conf' looks like:

server {
    listen 443 ssl;
    server_name docker.myDomain.org;

    ssl_certificate /etc/nginx/ssl/myDomain.org.cer;
    ssl_certificate_key /etc/nginx/ssl/myDomain.org.key;

    location / {
        # Do not allow connections from docker 1.5 and earlier
        # docker pre-1.6.0 did not properly set the user agent on ping, catch "Go *" user agents
        if ($http_user_agent ~ "^(docker\/1\.(3|4|5(?!\.[0-9]-dev))|Go ).*$" ) {
          return 404;
        }
        proxy_pass http://localhost:5000;
        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-Proto $scheme;
        proxy_read_timeout                  900;
    }

    access_log /var/log/nginx/docker-access.log;
    error_log /var/log/nginx/docker-error.log;
}

server {
    listen 80;
    server_name docker.myDomain.org;
    return 301 https://$host$request_uri;
}

what could be the issue here? (my tests currently are using postman and the browser); another private registy i use works with both my testing methods.

Since a have somewhat limited experience with nginx and issues finding informations on how to debug or troubleshoot such issues i hope for help here.

You are trying to proxy localhost

In the context of the nginx container, localhost is the container itself.

If you're using Docker Compose, you can simply use the container/service name http://servicename:5000

If not, you'll need to create a network and add both containers to it