To be able to use emulators and deploy the app(s) to the Google Cloud you need to install the gcloud command line tools. Follow the instructions [https://cloud.google.com/sdk/docs/install|here]. When you're on Linux preferably install from sources instead of using the apt package.
After installing the command line tools you need to initialize them and authenticate: https://cloud.google.com/sdk/docs/initializing
When you're done you should be able to type gcloud config list in your terminal and get an output like this:
account = uni@nhafkemeyer.com
disable_usage_reporting = False
project = playground-330914
Your active configuration is: [default]
The server app is an Node.js app using the Express framework. Therefore you need Node.js and npm (or yarn) installed. I recommend [https://github.com/nvm-sh/nvm|NVM], which is a version manager for Node.js. It allows you to use different node versions on one system and change between them. When you use nvm you can run nvm use or nvm install inside the server directory. This will set the active node version to the one specified in server/.nvmrc, or install it.
In the server directory run npm install to install the dependencies. All following commands should be run inside the server directory.
The app uses Google Cloud Datastore. To avoid needing to connect to the production instance you can use an emulator for local development and testing. First of all you need to install it:
gcloud components install cloud-datastore-emulator
Run the following command to start the emulator:
gcloud beta emulators datastore start --data-dir=.
The data-dir flag tells the emulator where to store its data. In this case we want it to store it in a /WEB-INF directory inside the server directory. After starting the emulator you need to set some environment variables so the applications knows to connect to the emulator instead of the production database. To automatically set them run
$(gcloud beta emulators datastore env-init --data-dir=.)
Now you're ready to start the application itself. Do so by running
npm run dev
App Engine