Script for weather reporting in Waybar

2024.07.17

While I was living in Argentina, we (my family) found ourselves checking for weather forecasts almost constantly — weather there can be quite unexpected, much more so that here in Mexico. So it took me a bit of tinkering to come up with a couple of simple scripts to show the weather forecast as part of my Waybar setup. I haven’t cared to share with anybody, as I believe them to be quite trivial and quite dirty.

But today, Víctor was asking for some slightly-related things, so here I go. Please do remember I warned: Dirty.

Forecast

I am using OpenWeather’s open API. I had to register to get an APPID, and it allows me for up to 1,000 API calls per day, more than plenty for my uses, even if I am logged in at my desktops at three different computers (not an uncommon situation). Having that, I set up a file named /etc/get_weather/, that currently reads:

# Home, Mexico City
LAT=19.3364
LONG=-99.1819

# # Home, Paraná, Argentina
# LAT=-31.7208
# LONG=-60.5317

# # PKNU, Busan, South Korea
# LAT=35.1339
#LONG=129.1055

APPID=SomeLongRandomStringIAmNotSharing

Then, I have a simple script, /usr/local/bin/get_weather, that fetches the current weather and the forecast, and stores them as /run/weather.json and /run/forecast.json:

#!/usr/bin/bash
CONF_FILE=/etc/get_weather

if [ -e "$CONF_FILE" ]; then
    . "$CONF_FILE"
else
    echo "Configuration file $CONF_FILE not found"
    exit 1
fi

if [ -z "$LAT" -o -z "$LONG" -o -z "$APPID" ]; then
    echo "Configuration file must declare latitude (LAT), longitude (LONG) "
    echo "and app ID (APPID)."
    exit 1
fi

CURRENT=/run/weather.json
FORECAST=/run/forecast.json

wget -q "https://api.openweathermap.org/data/2.5/weather?lat=${LAT}&lon=${LONG}&units=metric&appid=${APPID}" -O "${CURRENT}"
wget -q "https://api.openweathermap.org/data/2.5/forecast?lat=${LAT}&lon=${LONG}&units=metric&appid=${APPID}" -O "${FORECAST}"

This script is called by the corresponding systemd service unit, found at /etc/systemd/system/get_weather.service:

[Unit]
Description=Get the current weather

[Service]
Type=oneshot
ExecStart=/usr/local/bin/get_weather

And it is run every 15 minutes via the following systemd timer unit, /etc/systemd/system/get_weather.timer:

[Unit]
Description=Get the current weather every 15 minutes

[Timer]
OnCalendar=*:00/15:00
Unit=get_weather.service

[Install]
WantedBy=multi-user.target

(yes, it runs even if I’m not logged in, wasting some of my free API calls… but within reason)

Then, I declare a "custom/weather" module in the desired position of my ~/.config/waybar/waybar.config, and define it as:

"custom/weather": {
    "exec": "while true;do /home/gwolf/bin/parse_weather.rb;sleep 10; done",
"return-type": "json",
},

This script basically morphs a generic weather JSON description into another set of JSON bits that display my weather in the way I prefer to have it displayed as:

#!/usr/bin/ruby
require 'json'

Sources = {:weather => '/run/weather.json',
           :forecast => '/run/forecast.json'
          }
Icons = {'01d' => '🌞', # d → day
         '01n' => '🌃', # n → night
         '02d' => '🌤️',
         '02n' => '🌥',
         '03d' => '☁️',
         '03n' => '🌤',
         '04d'  => '☁️',
         '04n' => '🌤',
         '09d' => '🌧️',
         '10n' =>  '🌧 ',
         '10d' => '🌦️',
         '13d' => '❄️',
         '50d' => '🌫️'
        }

ret = {'text': nil, 'tooltip': nil, 'class': 'weather', 'percentage': 100}

# Current weather report: Main text of the module
begin
  weather = JSON.parse(open(Sources[:weather],'r').read)

  loc_name = weather['name']
  icon = Icons[weather['weather'][0]['icon']] || '？' + f['weather'][0]['icon'] + f['weather'][0]['main']

  temp = weather['main']['temp']
  sens = weather['main']['feels_like']
  hum = weather['main']['humidity']

  wind_vel = weather['wind']['speed']
  wind_dir = weather['wind']['deg']

  portions = {}
  portions[:loc] = loc_name
  portions[:temp] = '%s 🌡%2.2f°C (%2.2f)' % [icon, temp, sens]
  portions[:hum] = '💧 %2d%%' % hum
  portions[:wind] = '🌬%2.2fm/s %d°' % [wind_vel, wind_dir]
  ret['text'] = [:loc, :temp, :hum, :wind].map {|p| portions[p]}.join(' ')
rescue => err
  ret['text'] = 'Could not process weather file (%s ⇒ %s: %s)' % [Sources[:weather], err.class, err.to_s]
end

# Weather prevision for the following hours/days
begin
  cast = []
  forecast = JSON.parse(open(Sources[:forecast], 'r').read)
  min = ''
  max = ''

  day=Time.now.strftime('%Y.%m.%d')
  by_day = {}
  forecast['list'].each_with_index do |f,i|
    by_day[day] ||= []
    time = Time.at(f['dt'])
    time_lbl = '%02d:%02d' % [time.hour, time.min]

    icon = Icons[f['weather'][0]['icon']] || '？' + f['weather'][0]['icon'] + f['weather'][0]['main']

    by_day[day] << f['main']['temp']
    if time.hour == 0
      min = '%2.2f' % by_day[day].min
      max = '%2.2f' % by_day[day].max
      cast << '        ↑ min: <b>%s°C</b> max: <b>%s°C</b>' % [min, max]
      day = time.strftime('%Y.%m.%d')
      cast << '     ┍━━━━━┫  <b>%04d.%02d.%02d</b> ┠━━━━━┑' %
              [time.year, time.month, time.day]
    end
    cast << '%s | %2.2f°C | 🌢%2d%% | %s %s' % [time_lbl,
                                                f['main']['temp'],
                                                f['main']['humidity'],
                                                icon,
                                                f['weather'][0]['description']
                                               ]
  end
  cast << '        ↑ min: <b>%s</b>°C max: <b>%s°C</b>' % [min, max]

  ret['tooltip'] = cast.join("\n")
  
rescue => err
  ret['tooltip'] = 'Could not process forecast file (%s ⇒ %s)' % [Sources[:forecast], err.class, err.to_s]
end


# Print out the result for Waybar to process
puts ret.to_json

The end result? Nothing too stunning, but definitively something I find useful and even nicely laid out:

Screenshot

Do note that it seems OpenWeather will return the name of the closest available meteorology station with (most?) recent data — for my home, I often get Ciudad Universitaria, but sometimes Coyoacán or even San Ángel Inn.