Improve CLI error reporting

lib/producer/core/cli.rb

@@ -17,8 +17,9 @@ module Producer
           rescue ArgumentError => e
             stderr.puts e.message
             exit EX_USAGE
-          rescue RuntimeError => e
-            stderr.puts "#{e.class.name.split('::').last}: #{e.message}"
+          rescue Exception => e
+            ef = ErrorFormatter.new(force_cause: [RecipeEvaluationError])
+            stderr.puts ef.format e
             exit EX_SOFTWARE
           end
         end

lib/producer/core/error_formatter.rb

@@ -0,0 +1,53 @@
+module Producer
+  module Core
+    class ErrorFormatter
+      def initialize(debug: false, force_cause: [])
+        @debug        = debug
+        @force_cause  = force_cause
+      end
+
+      def debug?
+        !!@debug
+      end
+
+      def format(exception)
+        lines = format_exception exception
+
+        if debug? && exception.cause
+          lines << ''
+          lines << 'cause:'
+          lines << format_exception(exception.cause, filter: false)
+        end
+
+        lines.join("\n")
+      end
+
+      private
+
+      def format_exception(exception, filter: true)
+        [
+          format_message(exception),
+          *format_backtrace(exception.backtrace, filter: filter)
+        ]
+      end
+
+      def format_message(exception)
+        exception = exception.cause if @force_cause.include? exception.class
+        "#{exception.class.name.split('::').last}: #{exception.message}"
+      end
+
+      def format_backtrace(backtrace, filter: true)
+        backtrace = filter_backtrace backtrace if filter
+        indent_backtrace backtrace
+      end
+
+      def filter_backtrace(backtrace)
+        backtrace.reject { |l| l =~ /\/producer-\w+\/(?:bin|lib)\// }
+      end
+
+      def indent_backtrace(backtrace)
+        backtrace.map { |e| '  %s' % e }
+      end
+    end
+  end
+end

lib/producer/core/errors.rb

@@ -2,8 +2,10 @@ module Producer
   module Core
     Error                       = Class.new(StandardError)
     RuntimeError                = Class.new(RuntimeError)
+
     ArgumentError               = Class.new(Error)
     ConditionNotMetError        = Class.new(Error)
+    RecipeEvaluationError       = Class.new(RuntimeError)
     RemoteCommandExecutionError = Class.new(RuntimeError)
     RegistryKeyError            = Class.new(RuntimeError)
   end

lib/producer/core/recipe/file_evaluator.rb

@@ -5,7 +5,14 @@ module Producer
         class << self
           def evaluate(file_path, env)
             content = File.read(file_path)
-            Recipe.new(env).tap { |o| o.instance_eval content, file_path }
+            begin
+              Recipe.new(env).tap { |o| o.instance_eval content, file_path }
+            rescue Exception => e
+              fail RecipeEvaluationError, e.message, [
+                '%s (recipe)' % file_path,
+                *e.backtrace
+              ]
+            end
           end
         end
       end