If you need to upgrade your Digital Ocean droplet to the most recent Ubuntu (currently 16.04 LTS), I will copy your data offsite, destroy and replace your current droplet with the latest Ubuntu, copy your data back to your fresh droplet and install all the pieces that Discourse needs. Everything gets updated to the latest version: Docker, Postgres, and Nginx.
Since your droplet is rebuilt rather than creating a new one, your DNS records do not need to be changed.
This process requires as much as two hours of downtime, though if you need it, you are probably down already.
To complete this process I need access to your server and your Digital Ocean account. Log in to your server as root and issue this command:
Then go to Digital Ocean’s API page and generate an API key to send me. (It will be a big string of random numbers and letters.)