Deploy Back end server step in Play billing sample app - firebase

Question

I've followed all the steps in here to get the "Classy Taxi: Google Play Billing Subscriptions Android App Java Sample" running, however on the last step I'm very confused, it´s not clear to me as to how I´m supposed to deploy the back-end, here are the steps:
These are steps to build the backend server code located here
Make sure you have installed Node.js, npm, and Firebase CLI.
Run npm install to install dependencies.
Configure Cloud Functions for Firebase with your Android app and subscription products:
firebase use --add {your_firebase_project_id}
firebase functions:config:set app.package_name="your_android_application_id"
firebase functions:config:set app.basic_plan_sku="your_basic_subscription_product_sku_id"
firebase functions:config:set app.premium_plan_sku="your_premium_subscription_product_sku_id"
Run firebase deploy to deploy your backend to Cloud Functions for Firebase.
On the steps it´s not clear as to how the server will be deployed, it only mentioned the app id and the products SKU´s but not the code for the server so I need help clarifying that, please. I would like to see steps by step how to deploy the server.
This is what I´m currently doing:
1. Go to the root folder for the server
2. Open cmd from that folder
3. run the commands listed on the docs.
4. then I get this error:
=== Deploying to 'billing-project-c9f03'...
i deploying functions, hosting
Running command: npm --prefix "$RESOURCE_DIR" run lint
npm ERR! code ENOENT
npm ERR! syscall open
npm ERR! path C:\Users\frank\Desktop\Billing app\ClassyTaxiServer\server\package.json
npm ERR! errno -4058
npm ERR! enoent ENOENT: no such file or directory, open 'C:\Users\frank\Desktop\Billing app\ClassyTaxiServer\server\package.json'
npm ERR! enoent This is related to npm not being able to find a file.
npm ERR! enoent
npm ERR! A complete log of this run can be found in:
npm ERR! C:\Users\frank\AppData\Roaming\npm-cache\_logs\2020-04-13T01_21_30_198Z-debug.log
Error: functions predeploy error: Command terminated with non-zero exit code429496323
But I see the package.json file on the root folder.

Answer 1

See the Firebase CLI reference. This should be the project's root directory ClassyTaxiServer; assuming that you've ran all previous steps successfully, before attempting to firebase deploy. firebase.json knows what to do... however, that file is the actual problem; see PR #289.
Update firebase.json to this version and it should work out:
{
"functions": {
"predeploy": [
"npm --prefix \"$RESOURCE_DIR\" run lint",
"npm --prefix \"$RESOURCE_DIR\" run build"
],
"source": "."
},
"hosting": {
"public": "webapp",
"ignore": [
"firebase.json",
"**/.*",
"**/node_modules/**"
],
"rewrites": [ ]
}
}