Generates a migration. ## Examples mix ecto.gen.migration add_posts_table mix ecto.gen.migration add_posts_table -r Custom.Repo By default, the migration will be generated to the "priv/YOUR_REPO/migrations" directory of the current application but it can be configured by specify the `:priv` key under the repository configuration. ## Command line options * `-r`, `--repo` - the repo to generate migration for (defaults to `YourApp.Repo`) * `--no-start` - do not start applications