Enable yaml aliases

lib/kamal/configuration.rb

@@ -25,7 +25,9 @@ def load_config_files(*files)
 
       def load_config_file(file)
         if file.exist?
-          YAML.load(ERB.new(IO.read(file)).result).symbolize_keys
+          # Newer Psych doesn't load aliases by default
+          load_method = YAML.respond_to?(:unsafe_load) ? :unsafe_load : :load
+          YAML.send(load_method, ERB.new(IO.read(file)).result).symbolize_keys
         else
           raise "Configuration file not found in #{file}"
         end

test/cli/main_test.rb

@@ -296,6 +296,19 @@ class CliMainTest < CliTestCase
     end
   end
 
+  test "config with aliases" do
+    run_command("config", config_file: "deploy_with_aliases").tap do |output|
+      config = YAML.load(output)
+
+      assert_equal ["web", "web_tokyo", "workers", "workers_tokyo"], config[:roles]
+      assert_equal ["1.1.1.1", "1.1.1.2", "1.1.1.3", "1.1.1.4"], config[:hosts]
+      assert_equal "999", config[:version]
+      assert_equal "registry.digitalocean.com/dhh/app", config[:repository]
+      assert_equal "registry.digitalocean.com/dhh/app:999", config[:absolute_image]
+      assert_equal "app-999", config[:service_with_version]
+    end
+  end
+
   test "init" do
     Pathname.any_instance.expects(:exist?).returns(false).times(3)
     Pathname.any_instance.stubs(:mkpath)

test/fixtures/deploy_with_aliases.yml

@@ -0,0 +1,36 @@
+# helper aliases
+chicago_hosts: &chicago_hosts
+  hosts:
+    - 1.1.1.1
+    - 1.1.1.2
+tokyo_hosts: &tokyo_hosts
+  hosts:
+    - 1.1.1.3
+    - 1.1.1.4
+web_common: &web_common
+  env:
+    ROLE: "web"
+  traefik: true
+
+# actual config
+service: app
+image: dhh/app
+servers:
+  web:
+    <<: *chicago_hosts
+    <<: *web_common
+  web_tokyo:
+    <<: *tokyo_hosts
+    <<: *web_common
+  workers:
+    cmd: bin/jobs
+    <<: *chicago_hosts
+  workers_tokyo:
+    cmd: bin/jobs
+    <<: *tokyo_hosts
+env:
+  REDIS_URL: redis://x/y
+registry:
+  server: registry.digitalocean.com
+  username: user
+  password: pw