使用Docker Distillery版本运行迁移

Question

我正在尝试部署我的Phoenix 1.3应用程序。我已经设置了mix docker发布版本。现在我正在弄清楚如何运行迁移。

我决定采用定制发布命令的方法。我创建了这样的MigrationTask：

  defmodule SfiBackend.ReleaseTasks do
    @start_apps [
      :crypto,
      :ssl,
      :postgrex,
      :ecto,
      :logger
    ]

    def myapp do
      Application.ensure_started(:sfi_backend)
      Enum.each(@start_apps, fn app -> Application.ensure_started(app) end)
      Application.get_application(__MODULE__) |> IO.inspect(label: "My application:")
    end

    def repos, do: Application.get_env(myapp(), :ecto_repos, []) |> IO.inspect(label: "Repose:")

    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() |> IO.inspect(), &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

从技术上讲，它应该运行，因为我从Distillery Repo复制了它，但事实并非如此。

我收到这样的错误：

My application:: :sfi_backend
Repose:: [SfiBackend.Repo]
[SfiBackend.Repo]
Running migrations for sfi_backend
init terminating in do_boot ()
{"init terminating in do_boot",{#{'__exception__'=>true,'__struct__'=>'Elixir.ArgumentError',message=><<"argument error">>},[{ets,lookup_element,['Elixir.Ecto.Registry',nil,3],[]},{'Elixir.Ecto.Registry',lookup,1,[{file,"lib/ecto/registry.ex"},{line,18}]},{'Elixir.Ecto.Adapters.SQL',sql_call,6,[{file,"lib/ecto/adapters/sql.ex"},{line,251}]},{'Elixir.Ecto.Adapters.SQL','query!',5,[{file,"lib/ecto/adapters/sql.ex"},{line,198}]},{'Elixir.Ecto.Adapters.Postgres','-execute_ddl/3-fun-0-',4,[{file,"lib/ecto/adapters/postgres.ex"},{line,85}]},{'Elixir.Enum','-reduce/3-lists^foldl/2-0-',3,[{file,"lib/enum.ex"},{line,1755}]},{'Elixir.Ecto.Adapters.Postgres',execute_ddl,3,[{file,"lib/ecto/adapters/postgres.ex"},{line,85}]},{'Elixir.Ecto.Migrator','-migrated_versions/2-fun-0-',2,[{file,"lib/ecto/migrator.ex"},{line,44}]}]}}

Crash dump is being written to: erl_crash.dump...done

Answer 1

从堆栈跟踪中，它显示它在按名称查找后无法找到您的repo：

下面是ecto2.2中的lookup函数：

def lookup(repo_name) do
  pid = GenServer.whereis(repo_name)
  :ets.lookup_element(__MODULE__, pid, 3)
end

如果pid为nil，这将导致参数错误。看起来您是在seed中启动Repos，而不是在migrate中

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

将该代码分解到另一个函数中并从migrate调用它，以确保启动Repos。