Tools for running Distributed Elixir/Erlang with Nomad and Consul
The built-in Erlang distribution mechanisms are prefaced on using the Erlang Port Mapper Daemon, a process that runs on each box with an Erlang node and assigns it a port. On startup you feed your node with a list of hosts to connect to or connect manually in your application code. While this method can work in some cloud environments, cloud scheduling technologies such as Kubernetes or Nomad make it very inflexible and error prone.
There are several libraries and strategies for using the Kubernetes API to build a distributed cluster, but Consul provides us with a clean DNS api to retrieve information, while Nomad handles monitoring and scheduling services.
Caravan is split into two parts: The first is a set of modules that remove the
need for epmd by determing node ports by the node name. The idea and much of
the code is from the excellent article Erlang (and Elixir) distribution
without
epmd.
It's worth the read, and should explain what we're trying to accomplish with
the Caravan.Epmd module.
The second part utilizes libcluster to help with forming clusters automatically based on DNS SRV queries to Consul.
View extended documentation on Hex.
Note: Caravan is still pre 1.0, so there may be breaking changes until that time.
{:caravan, "~> 0.5.0"},