old_contents: #!/usr/bin/env python
  #    Licensed under the Apache License, Version 2.0 (the "License"); you may
  #    not use this file except in compliance with the License. You may obtain
  #    a copy of the License at
  #
  #         http://www.apache.org/licenses/LICENSE-2.0
  #
  #    Unless required by applicable law or agreed to in writing, software
  #    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
  #    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
  #    License for the specific language governing permissions and limitations
  #    under the License.
  
  import os
  import sys
  import traceback
  import yaml
  
  
  def exit_usage():
      print('Usage %s <yaml file or directory>' % sys.argv[0])
      sys.exit(1)
  
  def validate(filename):
      print('Validating %s' % filename)
      try:
          yaml.load(open(filename).read())
      except Exception:
          print(traceback.format_exc())
          return 1
      return 0
  
  if len(sys.argv) < 2:
      exit_usage()
  
  path_args = sys.argv[1:]
  exit_val = 0
  failed_files = []
  
  for base_path in path_args:
      if os.path.isdir(base_path):
          for subdir, dirs, files in os.walk(base_path):
              for f in files:
                  if f.endswith('.yaml'):
                      file_path = os.path.join(subdir, f)
                      failed = validate(file_path)
                      if failed:
                          failed_files.append(file_path)
                      exit_val |= failed
      elif os.path.isfile(base_path) and base_path.endswith('.yaml'):
          failed = validate(base_path)
          if failed:
              failed_files.append(base_path)
          exit_val |= failed
      else:
          print('Unexpected argument %s' % base_path)
          exit_usage()
  
  if failed_files:
      print('Validation failed on:')
      for f in failed_files:
          print(f)
  else:
      print('Validation successful!')
  sys.exit(exit_val)
  
new_contents: #!/usr/bin/env python
  #    Licensed under the Apache License, Version 2.0 (the "License"); you may
  #    not use this file except in compliance with the License. You may obtain
  #    a copy of the License at
  #
  #         http://www.apache.org/licenses/LICENSE-2.0
  #
  #    Unless required by applicable law or agreed to in writing, software
  #    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
  #    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
  #    License for the specific language governing permissions and limitations
  #    under the License.
  
  import os
  import sys
  import traceback
  import yaml
  
  
  def exit_usage():
      print('Usage %s <yaml file or directory>' % sys.argv[0])
      sys.exit(1)
  
  def validate(filename):
      print('Validating %s' % filename)
      try:
          tpl = yaml.load(open(filename).read())
      except Exception:
          print(traceback.format_exc())
          return 1
      # yaml is OK, now walk the parameters and output a warning for unused ones
      for p in tpl.get('parameters', {}):
          str_p = '\'%s\'' % p
          in_resources =  str_p in str(tpl.get('resources', {}))
          in_outputs =  str_p in str(tpl.get('outputs', {}))
          if not in_resources and not in_outputs:
              print('Warning: parameter %s in template %s appears to be unused'
                    % (p, filename))
  
      return 0
  
  if len(sys.argv) < 2:
      exit_usage()
  
  path_args = sys.argv[1:]
  exit_val = 0
  failed_files = []
  
  for base_path in path_args:
      if os.path.isdir(base_path):
          for subdir, dirs, files in os.walk(base_path):
              for f in files:
                  if f.endswith('.yaml'):
                      file_path = os.path.join(subdir, f)
                      failed = validate(file_path)
                      if failed:
                          failed_files.append(file_path)
                      exit_val |= failed
      elif os.path.isfile(base_path) and base_path.endswith('.yaml'):
          failed = validate(base_path)
          if failed:
              failed_files.append(base_path)
          exit_val |= failed
      else:
          print('Unexpected argument %s' % base_path)
          exit_usage()
  
  if failed_files:
      print('Validation failed on:')
      for f in failed_files:
          print(f)
  else:
      print('Validation successful!')
  sys.exit(exit_val)
  
subject: Add simple parameter test to yaml-validate.py