Publishing my vitals over the cloud

Having grown up with an over-protective and worrying father, my moving away never sat quite well with him.

After years of answering regular text messages assessing my well-being, I've decided to try out a different approach.

The Project

The idea is to build a dashboard that my father can regularly check to ensure that I'm alive and well. Hopefully reducing his anxiety and paranoia over my inescapable impending doom.

I decided to leverage my enthusiasm for Fitbit products with my understanding of the cloud to build this.

I settled on a VueJS + ExpressJS tech stack for fast prototyping. Details can always be found on my github.

Here's a very basic diagram of the concept

Using the Fitbit API

Having both a connected scale and wristband, the Fitbit API gives me access to a multitude of data points:

• Heart rate
• Daily activity
• Steps
• Body (Weight/Fat/BMI)
• Sleep info
• and many more

The goal is to have our server periodically retrieve data through the api.

Step 1: Registering an application

First things first, let's head over to the Fitbit developer console and register an application.

This will provide us with a CLIENT_ID/CLIENT_SECRET key pair required for an OAuth2 authentication.

Important :

The detailed heart rate data, also known as "Heart Rate Intraday Time Series" , is currently only available through the Personal app type, which we are using today.

Given that this project only displays data, the app should be marked as Read-Only.

Step 2: Authenticate

For a quick and painless authentication, I am using the passport-fitbit-oauth2 module.

Creating the Strategy

const Strategy = new FitbitStrategy({
  clientID:     config.CLIENT_ID,
  clientSecret: config.CLIENT_SECRET,
  callbackURL:  config.CALLBACK_URL,
  scope: [
    'sleep', 'weight', 'activity',
    'heartrate', 'location', 'profile',
    'nutrition', 'social'
  ]
}, (access_token, refresh_token, profile, done) => {
    // store the tokens
    done( ... );
})

Hooking it up to ExpressJS

passport.use(Strategy);

const authenticate = passport.authenticate('fitbit', {
  session: false,
  successRedirect: '/',
  failureRedirect: '/error'
});

app.get('/login', once, authenticate);
app.get('/callback', once, authenticate);

Access tokens eventually expire, that can be detected by the return of a 401 from the API. A sign for us to proceed with the Token Refresh.

Step 3: Retrieving data

Now that we have the Fitbit access token, we can start making calls to their Web API.

Here's an example of how to retrieve todays' Heart Rate Intraday Time Series:

GET https://api.fitbit.com/1/user/-/activities/heart/date/today/1d/1min.json

The server then returns the following JSON :

{
    "activities-heart-intraday": {
        "dataset": [
            {
                "time": "00:01:00",
                "value": 64
            },
            {
                "time": "00:02:00",
                "value": 63
            },
            //...
        ],
        "datasetInterval": 1,
        "datasetType": "minute"
    }
}

Building the dashboard

With this being a passion project, I pulled in a few libraries I love to quickly get going.

• Vue as a framework, a choice of comfort
• Vue Trend for slick looking graphs
• Font Awesome for the icons, a classic
• Animate.css exclusively for the heart pulsing animation

After a bit of wiring around, the following was birthed :

Securing the app

The web app exposes very personal data of mine, notably my fat percentage which can be seen sky rocketing around the Christmas holidays.

For this reason, I hooked up my own tiny CMS (Pocket), which provides me with users, access control and an admin panel out of the box.

Improvement ideas

Here are a few things I'm thinking of adding or have considered :

• My nutrition (would require me to input everything I eat)
• A button that reminds me to drink water
• My location, that may be a bit too much

Conclusion

Despite this project being extremely small and simplistic, I enjoyed the concept of making family members happier through technology.

Would love to hear your thoughts and experiences in writing code for well being.

Cheers,

Patrick