The dokku droplet as installed has a problem with the ruby buildpack, which depends on a nodejs.org download that has recently 301'd. This means no ruby apps are deployable.
It looks like dokku in the droplet wasn't installed using debian packages, which is the recommended way to run dokku now.
What's the easiest way to upgrade dokku so I can deploy again?
Looks like you've already figured it out, but for others that come along:
Newer Dokku Droplets do use the Debian packages, but older ones were installed from source. For convenience on those older Droplets, a local checkout of the Dokku git repository can be found in /root/dokku
To upgrade Dokku, you can run:
cd /root/dokku
git pull --tags origin master
sudo make install
@asb My current dokku version is v0.3.20-20-g2698ce6
When I run git pull --tags origin master I get:
fatal: Not a git repository (or any of the parent directories): .git
If I run sudo apt-get install dokku:
Reading package lists... Done
Building dependency tree
Reading state information... Done
E: Unable to locate package dokku
So I can't update my dokku version. How to proceed?
Ah, it appears that it was installed from source, so the instructions at https://github.com/progrium/dokku/blob/master/docs/upgrading.md apply.
WARNING: this will result in minutes of downtime.