Mix release -- deployment tasks

I have a Phoenix application that uses elasticsearch-elixir. I’m deploying with Mix releases, and trying to call an indexing function against this compiled release.

The docs have a guide on running these tasks in a Distillery release. They suggest adding the following module:

defmodule Backend.Release do
  # OTP apps that must be started in order for the code in this module
  # to function properly.
  #
  # Don't forget about Ecto and Postgrex if you're using Ecto to load documents
  # in your Elasticsearch.Store module!
  @start_apps [
    :crypto,
    :ssl,
    :postgrex,
    :ecto,
    :elasticsearch
  ]

  # Ecto repos to start, if any
  @repos Application.get_env(:my_app, :ecto_repos, [])

  # Elasticsearch clusters to start
  @clusters [Backend.Elasticsearch.Cluster]

  # Elasticsearch indexes to build
  @indexes [:instances]

  def build_elasticsearch_indexes() do
    start_services()
    IO.puts("Building indexes...")
    Enum.each(@indexes, &Elasticsearch.Index.hot_swap(Backend.Elasticsearch.Cluster, &1))
    stop_services()
  end

  # Ensure that all OTP apps, repos used by your Elasticsearch store,
  # and your Elasticsearch Cluster(s) are started
  defp start_services do
    IO.puts("Starting dependencies...")
    Enum.each(@start_apps, &Application.ensure_all_started/1)

    IO.puts("Starting repos...")
    Enum.each(@repos, & &1.start_link(pool_size: 1))

    IO.puts("Starting clusters...")
    Enum.each(@clusters, & &1.start_link())
  end

  defp stop_services do
    :init.stop()
  end
end

I’ve tried this setup, and then running my_app eval "MyApp.ReleaseTasks.build_elasticsearch_indexes" against the compiled binary. However, it causes an error:

Starting dependencies...
Starting repos...
Starting clusters...
Building indexes...
** (exit) exited in: GenServer.call(Backend.Elasticsearch.Cluster, :config, 5000)
    ** (EXIT) no process: the process is not alive or there's no process currently associated with the given name, possibly because its application isn't started
    (elixir) lib/gen_server.ex:1000: GenServer.call/3
    (elasticsearch) lib/elasticsearch/indexing/index.ex:32: Elasticsearch.Index.hot_swap/2
    (elixir) lib/enum.ex:783: Enum."-each/2-lists^foreach/1-0-"/2
    (elixir) lib/enum.ex:783: Enum.each/2
    lib/backend/release.ex:29: Backend.Release.build_elasticsearch_indexes/0
    (stdlib) erl_eval.erl:680: :erl_eval.do_apply/6
    (elixir) lib/code.ex:240: Code.eval_string/3

I think I remember reading somewhere that Application.ensure_all_started is no longer the recommended way to do something like this, but I can’t find it now. Does the above module look reasonable for Elixir 1.9 releases? Is there an obvious reason I’m missing that this doesn’t work?

The new recommended way you’re referring to is specifically for Ecto migrations and can be seen here

https://hexdocs.pm/phoenix/releases.html#ecto-migrations-and-custom-commands

So it doesn’t really cover your use case. Application.ensure_all_started/1 is still the correct way to start an application and its dependencies.

Hard to say what’s causing your error. Are you sure you’ve started all the required processes? Are there any others in your application supervision tree that might be missing?

2 Likes

Okay, great. If ensure_all_started is the correct way, then I’ll simply ensure_all_started(@app). Thank you!