burkeholland/burke · Datasets at Hugging Face

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OK! We’ve got a dynamic color scale based on hue, and wouldn’t you know it, we can just pass the hue to LIFX as simply as we pass a named color.


Now we just need to find out what the current temperature is, back into a hue and do that every few minutes. Serverless, here we come!

Serverless Timer Functions
Serverless is all the rage. It’s like HTML5 used to be: it doesn’t matter what it is, it only matters that you know the word and are not afraid to use it in a blog post.

For this example, we’ll use Azure Functions because there is support for timer triggers, and we can test those timer triggers locally before we deploy using VS Code. One of the things about Serverless that irritates me to no end is when I can’t debug it locally.

Using the Azure Functions Core Tools and the Azure Functions Extension for VS Code, I can create a new Serverless project and select a Timer Trigger.


Timer Triggers in Azure Functions are specified as Cron Expressions. Don’t worry, I didn’t know what that was either.

Cron Expressions allow you to get very specific with interval definition. Cron breaks things down into second, minute, hour, day, month, year. So if you wanted to run something every second of every minute of every hour of every day of every year, your expression would look like this…

* * * * * *
If you wanted to run it every day at 10:15, it would look like this…

* 15 10 * * *
If you wanted to run it every 5 minutes (which is what Azure defaults to), you specify that by saying “when minutes is divisible by 5.”

0 /5 * * *
For the purposes of this function, we set it to 2 minutes.


I am using a 2 minute interval because that’s how often we can call the weather API for free 💰.

Getting the Forecast From DarkSky
DarkSky has a wonderful weather API that you can call up to 1,000 times per day for free. If there are 1,440 minutes in a day (and there are), that means we can call DarkSky every 1.44 minutes per day and stay in the free zone. I just rounded up to 2 minutes because temperature doesn’t change that fast.

This is what our function looks like when we call the DarkSky API. All of my tokens, keys, latitude and longitude settings are in environment variables so they aren’t hardcoded. Those are set in the local.settings.json file. I used axios for my HTTP requests because it is a magical, magical package.

const axios = require('axios');

module.exports = function (context, myTimer) {
// build up the DarkSky endpoint
let endpoint = `${process.env.DS_API}/${process.env.DS_SECRET}/${process.env.LAT},
${process.env.LNG}`;

// use axios to call DarkSky for weather
axios
.get(endpoint)
.then(response => {
let temp = Math.round(response.data.currently.temperature);

// TODO: Set the color of the LIFX bulb
})
.catch(err => {
context.log(err.message);
});
};
Now that I have the temperature, I need to call the LIFX API. And wouldn’t you know it, someone has already created an npm package to do this called lifx-http-api. This is why you love JavaScript.

Setting the Bulb Hue
After the weather result comes back, I need to use the LIFX API instance and call the setState method. This method returns a promise which means that we need to nest promises. Nesting promises can get out of hand and could land us right back in callback hell, which is what we’re trying to avoid with promises in the first place.

Instead, we’ll handle the first promise and then return Promise.all which we can handle at another top-level then. This just prevents us from nesting then statements.

Remember kids, promises are just socially acceptable callbacks.

const axios = require('axios');
const LIFX = require('lifx-http-api');

let client = new LIFX({
bearerToken: process.env.LIFX_TOKEN
});

module.exports = function (context, myTimer) {
// build up the DarkSky endpoint
let endpoint = <code>${process.env.DS_API}/${process.env.DS_SECRET}/${
process.env.LAT
},${process.env.LNG}<code>;

// use axios to call DarkSky for weather
axios
.get(endpoint)
.then(response => {
let temp = Math.round(response.data.currently.temperature);

// make sure the temp isn't above 100 because that's as high as we can go
temp = temp < 100 ? temp : 100;

// determine the hue
let hue = 200 + (160 * (temp / 100));

// return Promise.all so we can resolve at the top level
return Promise.all([
data,
client.setState('all', { color: <code>hue:${hue}<code> })
]);
})
.then(result => {
// result[0] contains the darksky result
// result[1] contains the LIFX result
context.log(result[1]);
})
.catch(err => {
context.log(err.message);

OK! We’ve got a dynamic color scale based on hue, and wouldn’t you know it, we can just pass the hue to LIFX as simply as we pass a named color.

Now we just need to find out what the current temperature is, back into a hue and do that every few minutes. Serverless, here we come!

Serverless Timer Functions

Serverless is all the rage. It’s like HTML5 used to be: it doesn’t matter what it is, it only matters that you know the word and are not afraid to use it in a blog post.

For this example, we’ll use Azure Functions because there is support for timer triggers, and we can test those timer triggers locally before we deploy using VS Code. One of the things about Serverless that irritates me to no end is when I can’t debug it locally.

Using the Azure Functions Core Tools and the Azure Functions Extension for VS Code, I can create a new Serverless project and select a Timer Trigger.

Timer Triggers in Azure Functions are specified as Cron Expressions. Don’t worry, I didn’t know what that was either.

Cron Expressions allow you to get very specific with interval definition. Cron breaks things down into second, minute, hour, day, month, year. So if you wanted to run something every second of every minute of every hour of every day of every year, your expression would look like this…

* * * * * *

If you wanted to run it every day at 10:15, it would look like this…

* 15 10 * * *

If you wanted to run it every 5 minutes (which is what Azure defaults to), you specify that by saying “when minutes is divisible by 5.”

0 */5 * * * *

For the purposes of this function, we set it to 2 minutes.

I am using a 2 minute interval because that’s how often we can call the weather API for free 💰.

Getting the Forecast From DarkSky

DarkSky has a wonderful weather API that you can call up to 1,000 times per day for free. If there are 1,440 minutes in a day (and there are), that means we can call DarkSky every 1.44 minutes per day and stay in the free zone. I just rounded up to 2 minutes because temperature doesn’t change that fast.

This is what our function looks like when we call the DarkSky API. All of my tokens, keys, latitude and longitude settings are in environment variables so they aren’t hardcoded. Those are set in the local.settings.json file. I used axios for my HTTP requests because it is a magical, magical package.

const axios = require('axios');

module.exports = function (context, myTimer) {

// build up the DarkSky endpoint

let endpoint = `${process.env.DS_API}/${process.env.DS_SECRET}/${process.env.LAT},

${process.env.LNG}`;

// use axios to call DarkSky for weather

axios

.get(endpoint)

.then(response => {

let temp = Math.round(response.data.currently.temperature);

// TODO: Set the color of the LIFX bulb

})

.catch(err => {

context.log(err.message);

});

};

Now that I have the temperature, I need to call the LIFX API. And wouldn’t you know it, someone has already created an npm package to do this called lifx-http-api. This is why you love JavaScript.

Setting the Bulb Hue

After the weather result comes back, I need to use the LIFX API instance and call the setState method. This method returns a promise which means that we need to nest promises. Nesting promises can get out of hand and could land us right back in callback hell, which is what we’re trying to avoid with promises in the first place.

Instead, we’ll handle the first promise and then return Promise.all which we can handle at another top-level then. This just prevents us from nesting then statements.

Remember kids, promises are just socially acceptable callbacks.

const axios = require('axios');

const LIFX = require('lifx-http-api');

let client = new LIFX({

bearerToken: process.env.LIFX_TOKEN

});

module.exports = function (context, myTimer) {

// build up the DarkSky endpoint

let endpoint = <code>${process.env.DS_API}/${process.env.DS_SECRET}/${

process.env.LAT

},${process.env.LNG}<code>;

// use axios to call DarkSky for weather

axios

.get(endpoint)

.then(response => {

let temp = Math.round(response.data.currently.temperature);

// make sure the temp isn't above 100 because that's as high as we can go

temp = temp < 100 ? temp : 100;

// determine the hue

let hue = 200 + (160 * (temp / 100));

// return Promise.all so we can resolve at the top level

return Promise.all([

data,

client.setState('all', { color: <code>hue:${hue}<code> })

]);

})

.then(result => {

// result[0] contains the darksky result

// result[1] contains the LIFX result

context.log(result[1]);

})

.catch(err => {

context.log(err.message);