I have a an angular app that communicate with express server. I have linked the angular app to the express server. I could ping the link inside the angular container but shows error when used in the code.

**Docker Compose file**

```
myexpress: 
    build: express-server 
    links:
      - "mymongodb:mongo"
    ports:
      - "8080:3000" 
  angular: 
    build: angular 
    links:
      - "myexpress:express"
    ports:
      - "4200:4200" 

```

I can access the application at <http://localhost:4200/>. The code fragment of the http call is:

```
return this.http.post('http://express:3000/signup', body, {headers: headers})
      .map((response: Response) => response.json())
      .catch((error: Response) => Observable.throw(error.json()));

```

The console shows the following error:
[![enter image description here](https://i.stack.imgur.com/lQC9I.png)](https://i.stack.imgur.com/lQC9I.png)

How to access the link from the angular container?