applicationDefault method
Returns a credential created from the {@link https://developers.google.com/identity/protocols/application-default-credentials | Google Application Default Credentials} that grants admin access to Firebase services. This credential can be used in the call to {@link firebase-admin.app#initializeApp}.
Google Application Default Credentials are available on any Google infrastructure, such as Google App Engine and Google Compute Engine.
See {@link https://firebase.google.com/docs/admin/setup#initialize_the_sdk | Initialize the SDK} for more details.
@example
initializeApp({
credential: applicationDefault(),
databaseURL: "https://<DATABASE_NAME>.firebaseio.com"
});
@param httpAgent - Optional {@link https://nodejs.org/api/http.html#http_class_http_agent | HTTP Agent} to be used when retrieving access tokens from Google token servers.
@returns A credential authenticated via Google Application Default Credentials that can be used to initialize an app.
Implementation
external Credential applicationDefault([Agent httpAgent]);