fix: add release module and auto-migrate on Docker startup

Add SentinelCp.Release with migrate/rollback for running Ecto
migrations in production releases. Update Dockerfile CMD to run
migrations before starting the server so docker compose up works
out of the box.

Author: raffaelschneider

Dockerfile

@@ -75,4 +75,4 @@ EXPOSE 4000
 HEALTHCHECK --interval=30s --timeout=5s --start-period=10s --retries=3 \
   CMD curl -f http://localhost:4000/health || exit 1
 
-CMD ["/app/bin/sentinel_cp", "start"]
+CMD /app/bin/sentinel_cp eval "SentinelCp.Release.migrate()" && /app/bin/sentinel_cp start

lib/sentinel_cp/release.ex

@@ -0,0 +1,32 @@
+defmodule SentinelCp.Release do
+  @moduledoc """
+  Release tasks for running migrations in production.
+
+  Usage:
+
+      bin/sentinel_cp eval "SentinelCp.Release.migrate()"
+  """
+
+  @app :sentinel_cp
+
+  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