http://stackoverflow.com/a/22272491
Your precompile process is probably being killed because you are running out of RAM. You can confirm this by running top in another ssh session. To fix this, create a swap file that will be used when RAM is full.
Create SWAP Space on Ubuntu You will probably end up needing some swap space if you plan on using Rails on Digital Ocean 512MB RAM droplet. Specifically, you will run out of RAM when compiling the assets resulting in the process being quietly killed and preventing successful deployments.
To see if you have a swap files:
sudo swapon -s No swap file shown? Check how much disk space space you have:
df To create a swap file:
Step 1: Allocate a file for swap
sudo fallocate -l 2048m /mnt/swap_file.swap Step 2: Change permission
sudo chmod 600 /mnt/swap_file.swap Step 3: Format the file for swapping device
sudo mkswap /mnt/swap_file.swap Step 4: Enable the swap
sudo swapon /mnt/swap_file.swap Step 5: Make sure the swap is mounted when you Reboot. First, open fstab
sudo gedit /etc/fstab Finally, add entry in fstab
/mnt/swap_file.swap none swap sw 0 0 Save and exit. You're done adding swap. Now your rake assets:precompile should complete without being killed.