Yep, I use something like this to update my blog when I have added a new post or modified an existing one:

sudo -u www-data /var/www/blog/bin/mebe rpc "GenServer.call(Mebe2.Engine.Worker, :refresh, 30_000)"

Mix releases include the “rpc” script builtin.

I think you can do this in multiple ways. Define a port to receive messages or use the rpc to send messages directly in elixir.

/path/to/_build/prod/rel/my_app/bin/my_app rpc "Genserver.cast(...)"

Really cool solution!

ps: Security Notes:

• I hope your document root is not pointed at /var/www
• You have directory listing and all the other nice stuff disabled with the default apache or another unix handler
• For the future please create a specific user for your projects, applications, scripts and put them into respective directories and run from that location with that user

ie: blog

user: blog
homedir: /home/blog

$ > ps
... blog ...... /home/blog/bin/mebe ...... 

Hi and thanks for the concern. My document root is indeed not /var/www, and directory listing is not enabled. The blog could sure run with a different user, but there is nothing interesting on the server that the user could access, so I’m not too worried about it. But should leave a note to do it the next time I do something on the box.

But this is not at all related to the matter at hand.

To do this in development, you can start your application with a name (--name or --sname) and then use IEx’s --rpc-eval flag (and I think IEx also needs to be given a different name).

rpc is good; however fairly slow because it need to start up a separate erlang node just to talk to the existing running system. If you need to interact with the running system every second, you can make a simple server listening on a UNIX domain socket, that respond to a minimal text based API. This is fairly simple with gen_tcp. Another benefit (at least in my view) is you get to limit what you respond to. My client program is just a shell script that invokes socat.