Flask on Dokku on Digitalocean

howto.txt

Install the Dokku droplet - smallest possible digitalocean vm works fine
Make sure you add your ssh key so you can git over ssh and ssh into the image later
* On the image be sure to NOT set up IPv6
Boot the image - note the ip
Add a star alias on some domain you control and point it at that ip address - this lets you dokku up a lot of projects at somedomain.yourdomain.com
Go to http://[your IP address] to finalize dokku setup - set up virtual domains to make use of the star alias you just made
* You need to add your ssh public key here as well
* You CANNOT just add your key to authorised_keys - you need to use sshcommand - this enables the whole 'push to deploy' workflow
Follow the Flask-y steps here https://www.linode.com/docs/applications/containers/deploy-a-flask-application-with-dokku/

== communication between nodes
As you add auxiliary services you might want them to communicate. All containers in one Dokku app are created on the same network
- but they are unaware of each other's IP addresses and there's no DNS - that requires a user defined network (https://github.com/dokku/dokku/issues/2085)
I added a shared mount for communicating configuration data using 
dokku mount
and wrote a small script so each container is able to dump it's own location on disk so the other can read it. I include the script.

Don't forget to dokku ps:scale all your procs

Some experiences: Had a couple of botched updates due to network failure. This out Dokku on the fritz - bad state I could not retry my way out of. Fixed via a reboot. Which introduced the OTHER and NEW problem of Dokku not correctly killing old docker containers - so they all of a sudden rebooted as well - consuming all system resources. Had to kill all of these manually.
docker stop IDORNAME
docker rm IDORNAME
and of course while trying not to kill the actual stuff I had running.

I've also experienced failure to properly come up after reboot - had to do a
dokku ps:restart APPNAME
before the thing would run.