title: docker-compose.yml build fails with nginx configuration
body: <p>I'm trying to build a multi-container environment, with a client,server,worker &amp; nginx directories and I'm getting this error:</p>
  <pre><code>nginx_1     | 10-listen-on-ipv6-by-default.sh: info: /etc/nginx/conf.d/default.conf differs from the packaged version
  nginx_1     | /docker-entrypoint.sh: Launching /docker-entrypoint.d/20-envsubst-on-templates.sh
  nginx_1     | /docker-entrypoint.sh: Configuration complete; ready for start up
  nginx_1     | 2021/01/01 19:48:26 [emerg] 1#1: host not found in upstream &quot;client:3000&quot; in /etc/nginx/conf.d/default.conf:2
  nginx_1     | nginx: [emerg] host not found in upstream &quot;client:3000&quot; in /etc/nginx/conf.d/default.conf:2
  </code></pre>
  <blockquote>
  <p>Why it can't find my react service running on <code>3000</code> in my latest
  check the default port has not been changed</p>
  </blockquote>
  <h2>Architecture</h2>
  <ul>
  <li>Client: React project listens on default port <code>3000</code></li>
  <li>Server: The <code>API</code> server listens on port <code>5000</code></li>
  <li>Worker: functions in a <code>js</code> file</li>
  <li>Nginx: contains the <code>default.conf</code> and <code>Dockerfile.dev</code> (Dockerfile.dev is not omitted in the previous directories)</li>
  <li>Some more backend services</li>
  </ul>
  <h2>Nginx</h2>
  <p>This is my configuration where i try to forward requests from <code>/</code> to <strong>client</strong> and from <code>/api</code> to the <strong>server</strong></p>
  <h2>default.conf</h2>
  <pre><code>upstream client {
      server client:3000;
  }
  
  upstream api {
      server api:5000;
  }
  
  server {
      listen 80;
  
      location / {
          proxy_pass http://client;
      }
  
      locatoin /api {
          rewrite /api/(.*) /$1 break;
          proxy_pass http://api;
      }
  }
  </code></pre>
  <h2>docker-composer.yml</h2>
  <pre><code>version: '3'
  services:
    nginx:
      restart: always
      build:
        dockerfile: Dockerfile.dev
        context: ./nginx
      ports:
        - '8081:80'
  </code></pre>
  <h2>Dockerfile.dev</h2>
  <pre><code>FROM nginx
  COPY ./default.conf /etc/nginx/conf.d/default.conf
  </code></pre>