title: mysql in docker only works when changing folder name
body: <p>I was working on a project that uses docker-compose to bring up a container with a REST API  (python) and another with a mysql db. The API exposes an endpoint that calls the db (sqlalchemy). At some point, I started getting this error when calling the API:</p>
  <pre><code>sqlalchemy.exc.OperationalError: (pymysql.err.OperationalError) (1130, &quot;192.168.80.1' is not allowed to connect to this MySQL server&quot;)
  (Background on this error at: https://sqlalche.me/e/14/e3q8)
  </code></pre>
  <p>Then, I cloned a <a href="https://github.com/hogeline/sample_fastapi" rel="nofollow noreferrer">similar project</a> that uses the same libraries for everything and it worked. After this, I spent the next 6 hours in a <a href="https://en.wikipedia.org/wiki/Ship_of_Theseus" rel="nofollow noreferrer">ship-of-theseus</a>-like effort turning the working project into my own project, and it still worked. What I found out in the end is if I change the folder name of my existing, non-functional project, it will start functioning.</p>
  <p>Additional information:</p>
  <ul>
  <li>Every time I ran docker, I made sure to remove everything by running it in this fashion:</li>
  </ul>
  <pre><code>docker system prune -a &amp;&amp; docker-compose up --build --force-recreate
  </code></pre>
  <ul>
  <li>When copying my broken project into a new location, it was still broken</li>
  <li>When copying my broken project into a new location, but changing its folder name afterwards, it would work</li>
  </ul>
  <p>My question is - is there any form of caching that I don't know about that maybe gets invalidated when I change the folder name? Or is there another problem that I'm overlooking?</p>