This happens when you are trying to overwrite the default nginx config file which does not accept some root properties like http, user. If you need those extra configurations you can try copying what you have to /etc/nginx/nginx.conf

So instead of this: COPY default.conf /etc/nginx/conf.d/default.conf

Do this: COPY nginx.conf /etc/nginx/nginx.conf

Note: By copying to the /etc/nginx/conf.d/, you will be overwriting the default config.

I would like to add another solution to the ones proposed above. As above suggested, substituting nginx.conf or default.conf works. I do it in docker-compose.yml:

    volumes:
      - ./services/nginx.conf:/etc/nginx/nginx.conf

However, I came across the necessity to use environment variables in my nginx.conf file, which requires creating a template in /etc/nginx/templates/, which envsubst then outputs in /etc/nginx/conf.d, like explained here.

I came across the following errors:

• nginx: [emerg] "events" directive is not allowed here in /etc/nginx/conf.d/default.conf
• nginx: [emerg] "http" directive is not allowed here in /etc/nginx/conf.d/default.conf

Here is the working solution for the nginx.conf file (the file name does not matter here, since it is changed when copied to container, see docker-compose below, but I like to name it nginx.conf for clarity):

server {
  listen ${FE_PORT};
  location / {
    proxy_pass http://frontend:${FE_PORT};
  }
}
server {
  listen ${BE_PORT};
  location / {
    proxy_pass http://backend:${BE_PORT};
  }
}
server {
  listen ${SERVICE_PORT};
  location / {
    proxy_pass http://service:${SERVICE_PORT};
  }
}

And docker-compose.yml:

nginx:
    image: nginx
    container_name: nginx
    ports:
      - "${FE_PORT}:${FE_PORT}"
      - "${BE_PORT}:${BE_PORT}"
      - "${SERVICE_PORT}:${SERVICE_PORT}"
    environment:
      - FE_PORT
      - BE_PORT
      - SERVICE_PORT
    volumes:
      - ./nginx.conf:/etc/nginx/templates/default.conf.template

Solved this by overwrting nginx.conf.

Dockerfile

FROM nginx

COPY default.conf /etc/nginx/conf.d/default.conf

default.conf

worker_processes 1;

events { worker_connections 1024; }

http {

    sendfile on;

    upstream app {
        server app:8080;
    }

    server {
        listen 8080;

        location / {
            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;
        }
    }

}