Simple add swap on VPS

Create a Swap File
sudo fallocate -l 1G /swapfile

Enabling the Swap File
sudo chmod 600 /swapfile
sudo swapon /swapfile

Verify swap
free -h

Output
              total        used        free      shared  buff/cache   available
Mem:           488M         37M         96M        652K        354M        425M
Swap:          1.0G          0B        1.0G

Make the Swap File Permanent

Back up the /etc/fstab file in case anything goes wrong:
sudo cp /etc/fstab /etc/fstab.bak

Add the swap file information to the end of your /etc/fstab file by typing:
echo '/swapfile none swap sw 0 0' | sudo tee -a /etc/fstab