1 files changed, 105 insertions, 0 deletions
diff --git a/railties/lib/rails/secrets.rb b/railties/lib/rails/secrets.rb
new file mode 100644
index 0000000000..747cf31d7a
--- /dev/null
+++ b/railties/lib/rails/secrets.rb
@@ -0,0 +1,105 @@
+# frozen_string_literal: true
+
+require "yaml"
+require "active_support/message_encryptor"
+
+module Rails
+  # Greatly inspired by Ara T. Howard's magnificent sekrets gem. 😘
+  class Secrets # :nodoc:
+    class MissingKeyError < RuntimeError
+      def initialize
+        super(<<-end_of_message.squish)
+          Missing encryption key to decrypt secrets with.
+          Ask your team for your master key and put it in ENV["RAILS_MASTER_KEY"]
+        end_of_message
+      end
+    end
+
+    @cipher = "aes-128-gcm"
+    @root = File # Wonky, but ensures `join` uses the current directory.
+
+    class << self
+      attr_writer :root
+
+      def parse(paths, env:)
+        paths.each_with_object(Hash.new) do |path, all_secrets|
+          require "erb"
+
+          secrets = YAML.load(ERB.new(preprocess(path)).result) || {}
+          all_secrets.merge!(secrets["shared"].deep_symbolize_keys) if secrets["shared"]
+          all_secrets.merge!(secrets[env].deep_symbolize_keys) if secrets[env]
+        end
+      end
+
+      def key
+        ENV["RAILS_MASTER_KEY"] || read_key_file || handle_missing_key
+      end
+
+      def encrypt(data)
+        encryptor.encrypt_and_sign(data)
+      end
+
+      def decrypt(data)
+        encryptor.decrypt_and_verify(data)
+      end
+
+      def read
+        decrypt(IO.binread(path))
+      end
+
+      def write(contents)
+        IO.binwrite("#{path}.tmp", encrypt(contents))
+        FileUtils.mv("#{path}.tmp", path)
+      end
+
+      def read_for_editing(&block)
+        writing(read, &block)
+      end
+
+      private
+        def handle_missing_key
+          raise MissingKeyError
+        end
+
+        def read_key_file
+          if File.exist?(key_path)
+            IO.binread(key_path).strip
+          end
+        end
+
+        def key_path
+          @root.join("config", "secrets.yml.key")
+        end
+
+        def path
+          @root.join("config", "secrets.yml.enc").to_s
+        end
+
+        def preprocess(path)
+          if path.end_with?(".enc")
+            decrypt(IO.binread(path))
+          else
+            IO.read(path)
+          end
+        end
+
+        def writing(contents)
+          tmp_file = "#{File.basename(path)}.#{Process.pid}"
+          tmp_path = File.join(Dir.tmpdir, tmp_file)
+          IO.binwrite(tmp_path, contents)
+
+          yield tmp_path
+
+          updated_contents = IO.binread(tmp_path)
+
+          write(updated_contents) if updated_contents != contents
+        ensure
+          FileUtils.rm(tmp_path) if File.exist?(tmp_path)
+        end
+
+        def encryptor
+          @encryptor ||= ActiveSupport::MessageEncryptor.new([ key ].pack("H*"), cipher: @cipher)
+        end
+    end
+  end
+end