Add migration_command accessor for overriding (#242)

With rails 6 multiple database support the `db:migrate` command isn't always
what is needed when deploying to an environment.

Other usecases are only running migrations for one of the databases using
something like `db:migrate:primary`.

Exposing the accessor `migration_command` allows flexibility for more scenarios.

CHANGELOG.md

@@ -1,6 +1,7 @@
 # [master][]
 
 * Your contribution here!
+* Added option `:migration_command` to allow overriding the default `db:migrate` used.
 
 # [1.5.0][] (May 15 2020)
 

README.md

@@ -60,6 +60,9 @@ set :migration_role, :db
 # Defaults to the primary :db server
 set :migration_servers, -> { primary(fetch(:migration_role)) }
 
+# Defaults to `db:migrate`
+set :migration_command, 'db:migrate'
+
 # Defaults to false
 # Skip migration if files in db/migrate were not modified
 set :conditionally_migrate, true

lib/capistrano/tasks/migrations.rake

@@ -22,7 +22,7 @@ namespace :deploy do
     on fetch(:migration_servers) do
       within release_path do
         with rails_env: fetch(:rails_env) do
-          execute :rake, 'db:migrate'
+          execute :rake, fetch(:migration_command)
         end
       end
     end
@@ -36,5 +36,6 @@ namespace :load do
     set :conditionally_migrate, fetch(:conditionally_migrate, false)
     set :migration_role, fetch(:migration_role, :db)
     set :migration_servers, -> { primary(fetch(:migration_role)) }
+    set :migration_command, -> { fetch(:migration_command, 'db:migrate') }
   end
 end