[Firebase + Angular] Multi-tenancy apps

Just a very general note perhaps, and to share our own experience. We ended
up deciding to do the following:

    - We created a single Firebase instance
    - This allowed us to locate all of our user information within a single
    instance
    - For each user, we create a node
    - For each user we create a separate "user record" in which we record
    the node for which they have access
    - We use security rules to control access to that node

The security rule looks something like this:

"rules": {
     ".read": "root.child('users').child(auth.uid).child('accessNode').val()
=== true",
     ".write":
"root.child('users').child(auth.uid).child('accessNode').val() === true",

To summarize the challenge we had and the thinking about separate vs single
Firebase apps:

    - If you create separate instances of Firebase, this gives the benefit
    that you can very clearly partition the instances and clients
    - But it makes shared structures more difficult. In particular, how do
    you "stand up" a new instance, how do you aggregate data across multiple
    instances, and do you store user or analytics data in as many separate
    places as you have clients

We felt there was efficiency in realizing that the Firebase authentication
and permissions are incredibly robust. And because Firebase is entirely
based on URLs, we could keep everything within one Firebase app while
assigning the user to their own node to which they have permission.

Not sure if this is helpful, but we spent a lot of time thinking about the
long-term trade-offs between separate apps vs a single one, and a single
one wins hands-down, especially because of Firebase security and rules.

Thank you Doug for sharing this....most helpful.