We’ll cover a simple example of sending a slack message every morning to get the day weather’s forecast: min-max temp and an emoji depicting what the sky will be like, using OpenWeatherMap free API.

Using Node-RED, an automation tool based on a visual interface, the bot is built with 0 code (or maybe a maximum of 2 lines).

Final Node-RED flow sending the weather to Slack Slack mobile notification with the daily weather forecast

Preparation

Intro

The goal is to create an automated bot that sends weather information every morning on a slack channel with 0 code (or maybe a maximum of 2 lines). To do so, we’re going to use Node-RED, an automation tool based on a visual interface to query APIs and trigger external tools. See it like a free, highly customizable and self-hosted IFTTT. Each action is a Node and is connected to another ones/ones with wires.

Install and run

Node red install doc

$ node -v # >=  8.x
$ sudo npm install -g --unsafe-perm node-red # install node red globally
$ node-red # will create a ~/.node-red folder to store config & data
Welcome to Node-RED
===================
22 Nov 21:53:17 - [info] Node-RED version: v0.19.5
22 Nov 21:53:17 - [info] Node.js  version: v8.12.0
22 Nov 21:53:23 - [info] User directory : /home/florian/.node-red
22 Nov 21:53:23 - [info] Server now running at http://127.0.0.1:1880/

Go ahead and open http://127.0.0.1:1880/, you’ll have an empty flow open by default: Empty Node-RED flow editor at localhost:1880

Walkthrough

Discover

Drag n drop an inject, a debug, connect them together, hit Deploy, click on the blue square on the left of the inject node and open the debug console: Node-RED inject node connected to debug node

This is the very first step! This is what happened:

  • inject creates a global Javascrippt object msg with the key payload containing the actual int timestamp
  • inject sends it to the Debug
  • debug displays in the console the default configured output msg.payload

Double-clicking on the Debug node displays the configuration: Node-RED debug node configuration panel

Build the weather bot

Connect to Open Weather Map

Create API key on Open Weather Map and use it in the following endpoint:

https://api.openweathermap.org/data/2.5/weather?q=Paris,fr&appid=[APP_ID]&units=metric

Default call for testing https://samples.openweathermap.org/data/2.5/weather?q=London,uk&appid=b6907d289e10d714a6e88b30761fae22

Look for the node http request, set the endpoint and change the return to be a JSON object: Node-RED http request node returning a JSON object

Deploy and run! OpenWeatherMap API response displayed in Node-RED debug

And it took what, 5 min? Sweeet…

Format

Use the template node a little bit of moustache templating and here we are:

{{payload.main.temp_min}}/{{payload.main.temp_max}}

Node-RED template node with moustache temperature format Node-RED weather call output with min and max temperatures

Send to Slack

Install the Node red slack module

npm install node-red-contrib-slack

Make sure you have a webhook configured on your slack, i.e. https://my_instance.slack.com/apps/manage/custom-integrations: Slack custom integration incoming webhook configuration

And use the slack node with the correct Webhook URL: Node-RED slack node configured with webhook URL

CRON it with Node RED

Think of using it on a daily basis? Node RED has a much easier system than Linux’s CRONs.

Open up the inject node and define the Regular setting. Node-RED inject node regular schedule settings

Going further

You now have a fully working bot sending weather information every morning! Going further: display an emoji based on payload.weather[0].id (see https://openweathermap.org/weather-conditions), connect to your home IoT, your smart mirror…