Export FireStore database

CloneFireStore.js 

const firebase = require('firebase-admin');
const serviceAccountSource = require("./source.json"); // source DB key
const serviceAccountDestination = require("./destination.json"); // destiny DB key

const sourceAdmin = firebase.initializeApp({
  credential: firebase.credential.cert(serviceAccountSource)
});

const destinyAdmin = firebase.initializeApp({
  credential: firebase.credential.cert(serviceAccountDestination)
}, "destination");

/**
* This schema is how your DB is organized in a tree structure. You don't have to care about the Documents
* but you do need to inform the name of your collections and any sub collections, in this
* case we have two collections called users and groups, the all have their documents, but
* the collection users has its own sub collections, friends and groups, which again have their
* own sub collection, messages.
* @type {{groups: {}, users: {groups: {messages: {}}, friends: {messages: {}}}}}
*/
const schema = {
  users: {
    friends: {
      messages: {},
    },
    groups: {
      messages: {},
    },
  },
  groups: {},
};

const source = sourceAdmin.firestore();
const destination = destinationAdmin.firestore();

const copy = (sourceDBrep, destinationDBref, aux) => {
  return Promise.all(Object.keys(aux).map((collection) => {
    return sourceDBrep.collection(collection).get()
      .then((data) => {
        let promises = [];
        data.forEach((doc) => {
          const data = doc.data();
          promises.push(
            destinationDBref.collection(collection).doc(doc.id).set(data).then((data) => {
              return copy(sourceDBrep.collection(collection).doc(doc.id),
                destinationDBref.collection(collection).doc(doc.id),
                aux[collection])
            })
          );
        });
        return Promise.all(promises);
      })
  }));
};

copy(source, destination, aux).then(() => {
  console.log('copied');
});

ExportFireStore.js

const admin = require('firebase-admin');
const serviceAccount = require("./key.json");

admin.initializeApp({
  credential: admin.credential.cert(serviceAccount)
});
const dumped = {};

const schema = {
  checkin: {},
  config: {},
  sections: {},
  voters: {}
};

var db = admin.firestore();
const dump = (dbRef, aux, curr) => {
  return Promise.all(Object.keys(aux).map((collection) => {
    return dbRef.collection(collection).get()
      .then((data) => {
        let promises = [];
        data.forEach((doc) => {
          const data = doc.data();
          if (!curr[collection]) {
            curr[collection] = {
              data: {},
              type: 'collection',
            };
            curr[collection].data[doc.id] = {
              data,
              type: 'document',
            }
          } else {
            curr[collection].data[doc.id] = data;
          }
          promises.push(dump(dbRef.collection(collection).doc(doc.id), aux[collection], curr[collection].data[doc.id]));
        });
        return Promise.all(promises);
      });
  })).then(() => {
    return curr;
  })
};
let aux = {...schema};
let answer = {};
dump(db, aux, answer).then((answer) => {
  console.log(JSON.stringify(answer, null, 4));
});

Use it: 

## Install lib
```
npm install firebase-admin
```

## Update keys file
## Update schema

## How to use
```
node exportFirestoreDB.js > firestore_data_bk.json
```