add release conf for performing migrations

lib/philomena/release.ex

@@ -0,0 +1,24 @@
+defmodule Philomena.Release do
+  @app :philomena
+
+  def migrate do
+    load_app()
+
+    for repo <- repos() do
+      {:ok, _, _} = Ecto.Migrator.with_repo(repo, &Ecto.Migrator.run(&1, :up, all: true))
+    end
+  end
+
+  def rollback(repo, version) do
+    load_app()
+    {:ok, _, _} = Ecto.Migrator.with_repo(repo, &Ecto.Migrator.run(&1, :down, to: version))
+  end
+
+  defp repos do
+    Application.fetch_env!(@app, :ecto_repos)
+  end
+
+  defp load_app do
+    Application.load(@app)
+  end
+end

post-receive

@@ -21,12 +21,6 @@ if git diff --name-only $oldrev $newrev | grep -Ee "^mix.(exs|lock)"; then
   mix deps.get || die "mix failed to update"
 fi
 
-# Run migrations
-if git diff --name-only $oldrev $newrev | grep "^priv/repo/migrations"; then
-  echo "Running database migrations"
-  mix ecto.migrate || die "ecto.migrate failed"
-fi
-
 # Compile assets
 if git diff --name-only $oldrev $newrev | grep "^assets/"; then
   echo "Compiling assets"
@@ -38,6 +32,12 @@ fi
 echo "Building release"
 mix release --overwrite || die "failed to generate release"
 
+# Run migrations
+if git diff --name-only $oldrev $newrev | grep "^priv/repo/migrations"; then
+  echo "Running database migrations"
+  _build/prod/rel/philomena/bin/philomena eval "Philomena.Release.migrate()" || die "ecto.migrate failed"
+fi
+
 # Include a task to restart your running appserver instances here.
 #
 # In general, you should have many app instances configured on different