Hi there
The first time I went to production I can say that it took me some time to take care of everything.
Deploying Elixir/Phoenix apps requires certain OS knowledge.
I have a vagrant box for each project locally. Sure, you can use Docker if you fancy or anyother containerization software however there are some hidden costs to this approach.
I make sure that the VPS OS is the same as the OS I’ll be using in Vagrant. For most projects it’s just copy pasting the vagrant setup file.
Then I’ve created a simple bash script which compiles everything from within a virtual machine with distillery and copies it via SCP, extracts & runs it on the host. (You can compare it to edeliver.. however it’s simpler and what I need)
Shouldn’t take more than 10 minutes for the whole compilation stuff. If you use distillery you won’t need to install anything else on the VPS since you’ll get a self contained binary.
I currently run multiple Phoenix/elixir apps on a single Linode VPS. Phoenix gets routed via NGINX on a per domain basis. My usage of nginx is purely based on the fact that I also run some PHP compatible scripts on the same server.
For high performance apps I’d recommend using HAproxy since it goes better AND has more statistics. This way you don’t need to setup 10 vps’es for 10 apps 
The only downside to this is that yes, I need to configure a systemd service manually for each app. Nginx setupalso needs to be defined manually. These happen only the first time. After that it’s just reloading the vagrant box and deploying it.
I’d also recommend something else if you ever have issues with DB migrations. Or if you want to work directly on the remote DB in a secure way, at least for the migration of the data part
This may seem as less good practice from a security standpoint however if you use public key certificates it’s all good . Set up a reverse port forwarding from your production postgresql (or another DB) to your localhost.
This way you can use the remote database locally. All over an encrypted connection and you need not modify anything in postgresql to allow outgoing IP’s since everything will be done via localhost.
ssh -L 40001:localhost:5432 user@remotehost.net -p 2887
Where localhost is the hostname and 40001 is the local port you’ll use/
The -p 2887 indicates that I’ll be using that port for SSH instead of the default SSH port.
The above can be used for everything else as well including observing your app locally, migration of big data. All from your own box.
Good luck!
