dolarPy

Checks USD/PYG exchange rate from several sites, with a calculator, RESTful API and a twitter bot

• Scraper: Checks USD/PYG exchange rate from several sites every 10 minutes, saves the info in a json file
• Webservice: Flask app to serve the API and display the main website with the calculator
• TwitterBot: Reads the webservice output and tweet it(in a human readable format)

DEMO/Webservice

http://dolar.melizeche.com/api/1.0/

Twitter Bot

https://twitter.com/DolarPy

Mobile

• For Android https://github.com/ivankoop/DolarPy-Android
• For Android-Kotlin https://github.com/LucasGinard/DolarPy-Android-Kotlin
• For iOS https://github.com/LucasGinard/DolarPy-iOS

API wrappers

• For Java https://github.com/melizeche/dolarpy-wrapper-java
• For Python https://github.com/melizeche/dolarpy-wrapper-python

Documentation in progress

Requirements

• Python 3.9+
• BeautifulSoup4
• Flask
• Tweepy

Install

git clone git@github.com:melizeche/dolarPy.git
cd dolarPy
python3 -m venv env
# if venv module is not installed install with `sudo apt install python3-venv`
source env/bin/activate
pip install -r requirements.txt
crontab -e (add coti.py) // See example below
python cotiapp.py

On macOS High Sierra with python3 (also most linux distros)

# pip3 is installed with Python3
pip3 install virtualenv
# creating the virtualenv
virtualenv -p python3 env
# activate the virtualenv:
source env/bin/activate
pip3 install -r requirements.txt
# and the run
# if you need to deactivate the virtualenv:
deactivate

Crontab format and example

MIN HOUR DAYofMONTH MONTH DAYofWEEK PYTHONPATH SCRIPT

So for check/update the exchange rate every 10 minutes between 6am and 8pm on weekdays

*/10 6-20 * * 1-5 /apps/dolarPy/env/bin/python /apps/dolarPy/coti.py

And for tweet the exchange rate at 8am, 12pm and 6pm on weekdays

0 8,12,18 * * 1-5 /apps/dolarPy/env/bin/python /apps/dolarPy/single_tweet_bot.py

Proxy (optional)

Some sources sit behind Cloudflare or firewalls that block datacenter IPs (the scraper then logs an error or a 403 and reports 0 for that source). To fetch them through another machine, open a SOCKS tunnel to it:

autossh -M 0 -f -N -D 1080 -o ServerAliveInterval=30 -o ServerAliveCountMax=3 user@other-server

requests honors the standard proxy variables (SOCKS support comes from PySocks, already in requirements.txt), so this routes every source through the tunnel:

*/10 6-20 * * 1-5 ALL_PROXY=socks5h://localhost:1080 /apps/dolarPy/env/bin/python /apps/dolarPy/coti.py

To proxy only the source that needs it, pass proxies= to that scraper's request and read the address from its own variable, e.g. FOO_PROXY:

proxy = os.environ.get("FOO_PROXY")
requests.get(url, timeout=10, proxies={"http": proxy, "https": proxy} if proxy else None)

To start the tunnel on boot, add the same autossh command to your crontab with @reboot.

This was first set up for Ueno, which was removed after the bank collapsed in November 2026 (Al Jazeera).

Tests

There are two suites, split by the question they answer.

Offline (default, no network) -- checks that coti.py keeps its own contract: every source is fetched from the right endpoint, a source that is down or redesigned degrades to zeros instead of breaking the others, dolar.json has the documented shape, and the API serves it.

pip install -r requirements-dev.txt
pytest

Live (opt-in) -- asks the real sites whether the scrapers still scrape. This is what catches a redesign, and it is what to run while fixing one:

pytest -m live              # every source
pytest -m live -k maxi      # just one, while tuning its selector

A live failure means the site changed its markup and the selector in coti.py needs updating (or the site is down/blocking). There is no saved copy of any page to keep in sync -- fixing a scraper is a one-file change.

The live suite also runs nightly in GitHub Actions, which opens an issue when a check fails on two consecutive runs.

Contributing

If it is a new feature, before contributing, open an issue and ask if your functionality is needed by the project.

1. Fork it!
2. Create your feature branch: git checkout -b my-new-feature
3. Commit your changes: git commit -am 'Add some feature'
4. Push to the branch: git push origin my-new-feature
5. Submit a pull request :D

Author

• Marcelo Elizeche Landó https://github.com/melizeche

Contributors / Thanks

• Alejo Carballude https://github.com/AlejoAsd
• Carlos Carvallo https://github.com/carloscarvallo
• Carlos Laspina https://github.com/claspina
• Carlos Vallejos https://github.com/cabupy
• Christian Zelaya https://github.com/eduzetapy
• Diego Díaz https://github.com/berithpy
• Diego Zacarías https://github.com/zv3
• Ivan Koop https://github.com/ivankoop
• Matías Sánchez https://github.com/MatiSanchez25
• Mauricio Medina https://github.com/mauri-medina
• Taras Samoilenko https://github.com/cos1715
• Alcides Rivarola https://github.com/alcides29
• Lucas Ginard https://github.com/LucasGinard
• Padaleiana https://github.com/padaleiana
• nestorcde https://github.com/nestorcde
• Ever Leiva https://github.com/EverML
• Enrique Zárate https://github.com/enrique-zarate
• Jorge Cáceres https://github.com/jacaceresf

TODO(APIv2)

• Better Documentation
• Add more currencies
• Databases support
• Historical data API endpoint

License

This project is licensed under the Apache 2.0 License - see the LICENSE.txt file for details