Angular -Google-Maps backend API key

Question

In general, this question is about how to use some dynamic content from the backend inside the module.config function in AngularJS.

In particular, this question relates to the GoogleMapApi provider in angular-google-maps

In my Angular app, the Google Maps API key is stored in the Firebase firewall. What I would like to do is set the API key for GoogleMapApiProvider

.config(function(uiGmapGoogleMapApiProvider) {
    uiGmapGoogleMapApiProvider.configure({
    key: 'your api key',
    }); 
})

I know that I only have providers and constants available in the configuration function of the Angular module. So I try to think about how to get the required API key from my Firebase firewall using $ firebaseProvider Any help or direction is most appreciated! Thanks!