Optional
httpAgent: AgentOptional HTTP Agent to be used when retrieving access tokens from Google token servers.
A credential authenticated via Google Application Default Credentials that can be used to initialize an app.
admin.initializeApp({
credential: admin.credential.applicationDefault(),
databaseURL: "https://<DATABASE_NAME>.firebaseio.com"
});
Returns a credential created from the Google Application Default Credentials that grants admin access to Firebase services. This credential can be used in the call to firebase-admin.app#initializeApp.
Google Application Default Credentials are available on any Google infrastructure, such as Google App Engine and Google Compute Engine.
See Initialize the SDK for more details.