only automigrate in prod env

config/config.exs

@@ -21,6 +21,8 @@ config :cannery, CanneryWeb.Endpoint,
   live_view: [signing_salt: "zOLgd3lr"],
   registration: System.get_env("REGISTRATION") || "invite"
 
+config :cannery, Cannery.Application, automigrate: false
+
 config :cannery, :generators,
   migration: true,
   binary_id: true,

config/prod.exs

@@ -15,6 +15,8 @@ config :cannery, Cannery.Repo,
   url: "ecto://postgres:postgres@localhost/cannery",
   pool_size: 10
 
+config :cannery, Cannery.Application, automigrate: true
+
 # Do not print debug messages in production
 config :logger, level: :info
 

lib/cannery/application.ex

@@ -15,13 +15,17 @@ defmodule Cannery.Application do
       # Start the PubSub system
       {Phoenix.PubSub, name: Cannery.PubSub},
       # Start the Endpoint (http/https)
-      CanneryWeb.Endpoint,
+      CanneryWeb.Endpoint
       # Start a worker by calling: Cannery.Worker.start_link(arg)
-      # {Cannery.Worker, arg},
-      # Automatically migrate on start
-      Cannery.Repo.Migrator
+      # {Cannery.Worker, arg}
     ]
 
+    # Automatically migrate on start in prod
+    children =
+      if Application.get_env(:cannery, Cannery.Application, automigrate: false)[:automigrate],
+        do: children ++ [Cannery.Repo.Migrator],
+        else: children
+
     # See https://hexdocs.pm/elixir/Supervisor.html
     # for other strategies and supported options
     opts = [strategy: :one_for_one, name: Cannery.Supervisor]