Running ecto migration via release from distillery

meraj

I have an elixir umbrella project with three applications. I am creating its binary (release) via distillery.

Running this command creates .tar.gz file in _build/prod/rel/se/releases/0.1.0:

MIX_ENV=prod mix release --env=qa

And I am able to extract and run the application. To run ecto migration I have added this module for release tasks [by following https://hexdocs.pm/distillery/running-migrations.html ]:

defmodule Se.ReleaseTasks do

@start_apps [
    :postgrex,
    :ecto
]

def myapp, do: Application.get_application(__MODULE__)

def repos, do: Application.get_env(myapp(), :ecto_repos, [])

def seed() do
    me = myapp()

    IO.puts "Loading #{me}.."
    # Load the code for myapp, but don't start it
    :ok = Application.load(me)

    IO.puts "Starting dependencies.."
    # Start apps necessary for executing migrations
    Enum.each(@start_apps, &Application.ensure_all_started/1)

    # Start the Repo(s) for myapp
    IO.puts "Starting repos.."
    Enum.each(repos(), &(&1.start_link(pool_size: 1)))

    # Run migrations
    migrate()

    # Run seed script
    Enum.each(repos(), &run_seeds_for/1)

    # Signal shutdown
    IO.puts "Success!"
    :init.stop()
end

def migrate, do: Enum.each(repos(), &run_migrations_for/1)

def priv_dir(app), do: "#{:code.priv_dir(app)}"

defp run_migrations_for(repo) do
    app = Keyword.get(repo.config, :otp_app)
    IO.puts "Running migrations for #{app}"
    Ecto.Migrator.run(repo, migrations_path(repo), :up, all: true)
end

def run_seeds_for(repo) do
    # Run the seed script if it exists
    seed_script = seeds_path(repo)
    if File.exists?(seed_script) do
    IO.puts "Running seed script.."
    Code.eval_file(seed_script)
    end
end

def migrations_path(repo), do: priv_path_for(repo, "migrations")

def seeds_path(repo), do: priv_path_for(repo, "seeds.exs")

def priv_path_for(repo, filename) do
    app = Keyword.get(repo.config, :otp_app)
    repo_underscore = repo |> Module.split |> List.last |> Macro.underscore
    Path.join([priv_dir(app), repo_underscore, filename])
end
end

Application is run and compiled with this code located in one of the umbrella project where we require migrations. After compilation and starting server, when I try to run it via:

bin/se_cloud command Elixir.Se.ReleaseTasks seed

I get this error:

Elixir.Se.ReleaseTasks.seed is either not defined or has a non-zero arity

Did anyone else encounter this issue? Or I am mis-configuring something here?

27 comments

#ecto #distillery #troubleshooting

0 6020 27

2018-04-26 20:46:57 UTC

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idi527

Can you connect to the remote shell bin/se_cloud remote_console and check that this module actually exists (or loaded)?

iex> :erlang.module_loaded(Elixir.Se.ReleaseTasks)
true # or false

Post #1

meraj

I did that and following is the output:

iex(se_cloud@127.0.0.1)1> :erlang.module_loaded(Elixir.Se.ReleaseTasks)
false

Post #2

idi527

That might be the problem. For some reason this module does not get loaded in your release. What “otp app” do you define this module in? Does that “otp app” get added to the release?

In other words, it seems that your app is named :se (judging by Se). Is :se anywhere in your rel/config.exs?

Post #3

meraj

Yes. I have it defined in my rel/config.exs as (it was in fact generated by distillery itself when I ran mix release.init I only added the set commands option.):

release :se_cloud do
set version: "0.1.0"
set commands: [
    "migrate": "rel/commands/migrate.sh"
]
set applications: [
    :runtime_tools,
    se: :permanent,
    se_web: :permanent
]
end

Post #4

idi527

Ok, and what’s the folder of the file where Se.ReleaseTasks is defined? Is it under apps/se/lib/?

Post #5

meraj

No this is file is defined under apps/se/

File name is release_tasks.ex

Post #6

meraj

After moving release_tasks.ex to app/se/lib and creating release again I am getting this:

iex(se_cloud@127.0.0.1)1> :erlang.module_loaded(Elixir.Se.ReleaseTasks)
true

However, now when I run the seed command, I am getting this error:

{“init terminating in do_boot”,{{badmatch,{error,{“no such file or directory”,“nil.app”}}},[{‘Elixir.Se.ReleaseTasks’,seed,0,[{file,“lib/release_tasks.ex”},{line,17}]},{init,start_em,1,},{init,do_boot,3,}]}}
init terminating in do_boot ({{badmatch,{error,{[],[]}}},[{Elixir.Se.ReleaseTasks,seed,0,[{},{}]},{init,start_em,1,},{init,do_boot,3,}]})

I also checked it from remote console:

iex(se_cloud@127.0.0.1)1> Application.get_application(:se)
nil

I am not sure whey getting this error now while I am able to run the bin/se_cloud start with seeing any error on console or logs.

Post #7

idi527

You probably need to load your application before running the migrations.

Post #8

meraj

Yes. In ReleaseTasks module I am trying to load application first, as you can see in my code:

def myapp, do: Application.get_application(:se)

But it is failing upon loading it. I also tried to run this via remote console:

iex(se_cloud@127.0.0.1)1> Application.get_application(:se)
nil

And getting this nil which means it is not able find application while I am able to run bin/se_cloud start without any error printed to console / logs.

Post #9

idi527

I don’t think Application.get_application(:se) should return anything but nil unless you have defined :se module for some application.

What you should probably do is

def myapp do
  Application.get_application(__MODULE__) || raise("couldn't get application for #{__MODULE__}")
end

I’ve added a raise/1 here to “fail fast” in the case no application gets found. It would also provide us with a more constructive error message (couldn't get application for Se.ReleaseTasks) than what we’ve had before ({{badmatch,{error,{“no such file or directory”,“nil.app”}}}).

Post #10

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