This program lets me know if I should water my balcony at night. It collects temperature data from https://www.weatherbit.io/ during the day into PostgreSQL. At the end of the day it sends an e-mail with the average temperature, if it was over 20 degrees Celcius. I could probably take into account more data like precipitation but this is a good start.
I implemented this idea before in Clojure and ClojureScript, but in those versions I didn't need the database since I used a historical API. That API is not free anymore and I don't want to pay 35 dollars a month for a reminder about watering my balcony. Since the requirements changed, I decided to do it in Haskell for fun and to learn something new.
Create a new login user (default name balcony) and a database (default name
balcony) and execute ddl.sql with that user.
Set the following environment variables. Those with defaults are optional.
BALCONY_SMTP_HOST (default smtp.gmail.com)
BALCONY_SMTP_USER
BALCONY_SMTP_PASS
BALCONY_DB_NAME (default balcony)
BALCONY_DB_HOST (default localhost)
BALCONY_DB_PORT (default 5432)
BALCONY_DB_PASS (default empty string)
BALCONY_WEATHER_API_KEY
BALCONY_MAIL_FROM
BALCONY_MAIL_TO (comma separated string)
BALCONY_MAIL_BODY (optional body template where {{avg}} will be replaced with the average)
stack build
stack install
Trigger the program via cron. I log every hour from 9 to 18 and send an e-mail at 19.
crontab -e
0 9-18 * * * /usr/bin/env bash -c '. $HOME/.profile ; balcony-exe log'
0 19 * * * /usr/bin/env bash -c '. $HOME/.profile ; balcony-exe mail'