I have 2 APIs and a front end that work in docker containers. They can all be created via docker-compose and I have an Nginx reverse proxy that should route to them using their hostnames i.e. api-1.my-project.localhost. In fact, I have had this process working, but every so often, like this morning, I get the "Non-existent domain" or "We can't find this site" when visiting it using these hostnames.

I don't believe the docker-compose.yml is all that important but I have included it here:

version: "3.2"
services:
  api-1:
    # Runs on port 5000
    image: my-companies-docker-registry.api-1
  api-2:
    # Runs on port 5000
    image: my-companies-docker-registry.api-2
  main-front-end:
    # Runs on port 3000
    image: my-companies-docker-registry.main-front-end
  my-project:
    image: nginx
    depends_on:
      - api-1
      - api-2
      - main-front-end
    ports:
      - 80:80
    volumes:
      - type: bind
        read_only: true
        source: ./nginx
        target: /etc/nginx

My nginx config looks like so:

events {}
http {
    # Api 1
    upstream api-1{
        server api-1:5000;
    }

    server {
        listen       80;
        server_name  api-1.my-project.localhost;

        location / {
            proxy_pass http://api-1;
        }
    }

    # Api 2
    upstream api-2 {
        server api-2:5000;
    }

    server {
        listen       80;
        server_name  api-2.my-project.localhost;

        location / {
            proxy_pass http://api-2;
        }
    }

    # Main Front end

    upstream main-front-end {
        server main-front-end:3000;
    }

    server {
        listen       80 default_server deferred;
        server_name  my-project.localhost www.my-project.localhost;

        location / {
            proxy_pass http://main-front-end;
            proxy_http_version 1.1;
            proxy_set_header Upgrade $http_upgrade;
            proxy_set_header Connection "Upgrade";
        }
    }
}

The aim of this is so that I can access the site using http://my-project.localhost and the APIs using api-1.my-project.localhost and api-2.my-project.localhost. As I have listen 80 default_server deferred by visiting http://localhost I can hit nginx, which lets me see my front end site. So docker-compose has bound the ports correctly.

At some point in the past, I have been able to access the sites using the my-project.localhost suffix but now this is no longer the case. This site suggests adding a host entry for every site, I don't remember doing this before, as there are a lot of sites, this would have taken a while but it is possible I did and now they have been removed. I am also aware that Nginx is not docker, so I have no idea how those hostnames would have been extracted and added to my machines host resolution process.

How could this have worked before and not now? And how can I get my setup to work without making manual host file changes?