You can detect city and country from an IP address by using the GeoLite database Show archive.org snapshot . This is a flat file you can copy into your project (~ 20 MB).
You can access the database using the geoip Show archive.org snapshot gem.
You need to attribute MaxMind Show archive.org snapshot if you are using the data.
Accuracy sort of sucks Show archive.org snapshot . For most countries 1/3 of addresses cannot be resolved within 40 kilometers, probably because the Internet doesn't work this way. Also you will lose 1.5% accuracy for each month you don't update the database file.

Rails Long Term Support

Rails LTS provides security patches for old versions of Ruby on Rails (2.3, 3.2, 4.2 and 5.2)

Detect city, country from IP address