Merge pull request #35497 from eileencodes/parse-yaml-without-erb-for-rake-tasks

Load YAML for rake tasks without parsing ERB

2 files changed, 36 insertions, 0 deletions

diff --git a/railties/lib/rails/application/configuration.rb b/railties/lib/rails/application/configuration.rb
index af3ec36064..83a7b6cf01 100644
--- a/railties/lib/rails/application/configuration.rb
+++ b/railties/lib/rails/application/configuration.rb
@@ -184,6 +184,26 @@ module Rails
         end
       end
 
+      # Load the database YAML without evaluating ERB. This allows us to
+      # create the rake tasks for multiple databases without filling in the
+      # configuration values or loading the environment. Do not use this
+      # method.
+      #
+      # This uses a DummyERB custom compiler so YAML can ignore the ERB
+      # tags and load the database.yml for the rake tasks.
+      def load_database_yaml # :nodoc:
+        if path = paths["config/database"].existent.first
+          require "rails/application/dummy_erb_compiler"
+
+          yaml = Pathname.new(path)
+          erb = DummyERB.new(yaml.read)
+
+          YAML.load(erb.result)
+        else
+          {}
+        end
+      end
+
       # Loads and returns the entire raw configuration of database from
       # values stored in <tt>config/database.yml</tt>.
       def database_configuration
diff --git a/railties/lib/rails/application/dummy_erb_compiler.rb b/railties/lib/rails/application/dummy_erb_compiler.rb
new file mode 100644
index 0000000000..4e92526969
--- /dev/null
+++ b/railties/lib/rails/application/dummy_erb_compiler.rb
@@ -0,0 +1,16 @@
+# frozen_string_literal: true
+
+# These classes are used to strip out the ERB configuration
+# values so we can evaluate the database.yml without evaluating
+# the ERB values.
+class DummyERB < ERB # :nodoc:
+  def make_compiler(trim_mode)
+    DummyCompiler.new trim_mode
+  end
+end
+
+class DummyCompiler < ERB::Compiler # :nodoc:
+  def compile_content(stag, out)
+    out.push "_erbout << 'dummy_compiler'"
+  end
+end