If they don't released the official version of ubuntu package yet then you should compile it for yourself from the source code but it can not guarantee works on your server. I strongly suggest you to wait for a while so you can see an official update. Using proper channels to update your system is always the best idea.

It's been released for 17d, how long should we expect DO to update our Ubuntu images to allow us continued use of LE? I am attempting to create new certificates, and I'm sure others are about to expire, and would really like an update on the timelines to get back on track without workarounds.

The latest info I have:

• whoever ports this to ubunut is working on porting it according to cerbot.eff
• certbot.eff.org says you can install certbot-auto wget https://dl.eff.org/certbot-auto chmod a+x certbot-auto certbot-auto accepts the same flags as certbot; it installs all of its own dependencies and updates the client code automatically.

I followed the directions and it indeed did install v0.21 but I did not try it out because I had renewed my keys by 1) stopping nginx 2) doing the manual thing and 3) restarting nginx

Here is the certbot.eff link