Allow skipping master key

README.md

@@ -244,6 +244,14 @@ ARG RUBY_VERSION
 FROM ruby:$RUBY_VERSION-slim as base
 ```
 
+### Using without RAILS_MASTER_KEY
+
+If you're using MRSK with older Rails apps that predate RAILS_MASTER_KEY, or with a non-Rails app, you can skip the default usage and reference:
+
+```yaml
+skip_master_key: true
+```
+
 ### Using accessories for database, cache, search services
 
 You can manage your accessory services via MRSK as well. The services will build off public images, and will not be automatically updated when you deploy:

lib/mrsk/commands/app.rb

@@ -98,6 +98,10 @@ class Mrsk::Commands::App < Mrsk::Commands::Base
     end
 
     def rails_master_key_arg
-      [ "-e", redact("RAILS_MASTER_KEY=#{config.master_key}") ]
+      if master_key = config.master_key
+        [ "-e", redact("RAILS_MASTER_KEY=#{master_key}") ]
+      else
+        []
+      end
     end
 end

lib/mrsk/configuration.rb

@@ -115,7 +115,9 @@ class Mrsk::Configuration
   end
 
   def master_key
-    ENV["RAILS_MASTER_KEY"] || File.read(Pathname.new(File.expand_path("config/master.key")))
+    unless raw_config.skip_master_key
+      ENV["RAILS_MASTER_KEY"] || File.read(Pathname.new(File.expand_path("config/master.key")))
+    end
   end
 
   def to_h

test/commands/app_test.rb

@@ -2,14 +2,18 @@ require "test_helper"
 require "mrsk/configuration"
 require "mrsk/commands/app"
 
-ENV["RAILS_MASTER_KEY"] = "456"
-
 class CommandsAppTest < ActiveSupport::TestCase
   setup do
+    ENV["RAILS_MASTER_KEY"] = "456"
+
     @config = { service: "app", image: "dhh/app", registry: { "username" => "dhh", "password" => "secret" }, servers: [ "1.1.1.1" ] }
     @app = Mrsk::Commands::App.new Mrsk::Configuration.new(@config)
   end
 
+  teardown do
+    ENV["RAILS_MASTER_KEY"] = nil
+  end
+
   test "run" do
     assert_equal \
       [:docker, :run, "-d", "--restart unless-stopped", "--name", "app-missing", "-e", "RAILS_MASTER_KEY=456", "--label", "service=app", "--label", "role=web", "--label", "traefik.http.routers.app.rule='PathPrefix(`/`)'", "--label", "traefik.http.services.app.loadbalancer.healthcheck.path=/up", "--label", "traefik.http.services.app.loadbalancer.healthcheck.interval=1s", "--label", "traefik.http.middlewares.app.retry.attempts=3", "--label", "traefik.http.middlewares.app.retry.initialinterval=500ms", "dhh/app:missing"], @app.run
@@ -27,4 +31,11 @@ class CommandsAppTest < ActiveSupport::TestCase
       [ :docker, :run, "--rm", "-e", "RAILS_MASTER_KEY=456", "dhh/app:missing", "bin/rails", "db:setup" ],
       @app.run_exec("bin/rails", "db:setup")
   end
+
+  test "run without master key" do
+    ENV["RAILS_MASTER_KEY"] = nil
+    @app = Mrsk::Commands::App.new Mrsk::Configuration.new(@config.tap { |c| c[:skip_master_key] = true })
+
+    assert @app.run.exclude?("RAILS_MASTER_KEY=456")
+  end
 end

test/configuration_test.rb

@@ -1,10 +1,10 @@
 require "test_helper"
 require "mrsk/configuration"
 
-ENV["RAILS_MASTER_KEY"] = "456"
-
 class ConfigurationTest < ActiveSupport::TestCase
   setup do
+    ENV["RAILS_MASTER_KEY"] = "456"
+
     @deploy = {
       service: "app", image: "dhh/app",
       registry: { "username" => "dhh", "password" => "secret" },
@@ -21,6 +21,10 @@ class ConfigurationTest < ActiveSupport::TestCase
     @config_with_roles = Mrsk::Configuration.new(@deploy_with_roles)
   end
 
+  teardown do
+    ENV["RAILS_MASTER_KEY"] = nil
+  end
+
   test "ensure valid keys" do
     assert_raise(ArgumentError) do
       Mrsk::Configuration.new(@deploy.tap { _1.delete(:service) })
@@ -134,6 +138,11 @@ class ConfigurationTest < ActiveSupport::TestCase
     assert_equal "456", @config.master_key
   end
 
+  test "skip master key" do
+    config = Mrsk::Configuration.new(@deploy.tap { |c| c[:skip_master_key] = true })
+    assert_nil @config.master_key
+  end
+
   test "volume_args" do
     assert_equal ["--volume", "/local/path:/container/path"], @config.volume_args
   end