outsider:
The relays coil current is 80 mA, twice the absolute maximum for an Atmega328 output pin, you need a switching transistor like 2N3904 or similar, and a spike suppression diode like 1N4148 across the coil, you could power 1 relay from the 5V pin if it's only intermittent.
I agree that is a proper way drive drive a standalone relay. That cannot be said of the aforementioned relay module. It looks like it has some smarts and stuff between the Arduino and the relay coil.