I have a component in my Ember app which returns data from a static markdown file.

```js
  didInsertElement() {
    fetch('markdown/faqs-content.md').then(response => {
      response.text().then(result => {
        this.set('markdown', result);
      });
    });
  }
```

When the app runs, the request goes to `http://localhost:4200/markdown/faqs-content.md` and everything works fine.

However, in mirage, I get this error:

`Mirage: Your app tried to GET '/markdown/faqs-content.md', but there was no route defined to handle this request. Define a route for this endpoint in your routes() config. Did you forget to define a namespace?`

The above happens, even though the following is included in `mirage/config.js`:

`this.passthrough();`

Presumably, this is because the API namespace is not included in the request URL.

The problem can be solved by adding the full URL to passthrough:

`this.passthrough('https://localhost:4201/markdown/faqs-content.md');`

Doing this has two issues: 

1. I don't always know the port that the app is served on, and
2. I don't want to lose the functionality of using `this.passThrough()`, which automatically invokes pass through for any API requests where there is no corresponding route in `mirage/config.js`.

I thus have 2 questions.

1. In `config.js`, is there any way of getting port that Ember server is running on, to allow something like `https://localhost:${port}/markdown/faqs-content.md`?
2. Is there a way that I can configure Mirage to pass through for the request to `https://localhost:4201/markdown/faqs-content.md`, and still allow it to pass through for any other requests that don't have a corresponding route defined?