How do you debug Google Deployment Manager templates?

I'm looking at this example, which uses this template. I added a print statement to it, but how do I see this output?

import base64
import hashlib
from StringIO import StringIO
import zipfile


def GenerateConfig(ctx):
  """Generate YAML resource configuration."""
  in_memory_output_file = StringIO()
  function_name = ctx.env['deployment'] + 'cf'
  zip_file = zipfile.ZipFile(
      in_memory_output_file, mode='w', compression=zipfile.ZIP_DEFLATED)



  ####################################################
  ############ HOW DO I SEE THIS????? ################
  print('heelo wworrld')
  ####################################################
  ####################################################



  for imp in ctx.imports:
    if imp.startswith(ctx.properties['codeLocation']):
      zip_file.writestr(imp[len(ctx.properties['codeLocation']):],
                        ctx.imports[imp])
  zip_file.close()
  content = base64.b64encode(in_memory_output_file.getvalue())
  m = hashlib.md5()
  m.update(content)
  source_archive_url = 'gs://%s/%s' % (ctx.properties['codeBucket'],
                                       m.hexdigest() + '.zip')
  cmd = "echo '%s' | base64 -d > /function/function.zip;" % (content)
  volumes = [{'name': 'function-code', 'path': '/function'}]
  build_step = {
      'name': 'upload-function-code',
      'action': 'gcp-types/cloudbuild-v1:cloudbuild.projects.builds.create',
      'metadata': {
          'runtimePolicy': ['UPDATE_ON_CHANGE']
      },
      'properties': {
          'steps': [{
              'name': 'ubuntu',
              'args': ['bash', '-c', cmd],
              'volumes': volumes,
          }, {
              'name': 'gcr.io/cloud-builders/gsutil',
              'args': ['cp', '/function/function.zip', source_archive_url],
              'volumes': volumes
          }],
          'timeout':
              '120s'
      }
  }
  cloud_function = {
      'type': 'gcp-types/cloudfunctions-v1:projects.locations.functions',
      'name': function_name,
      'properties': {
          'parent':
              '/'.join([
                  'projects', ctx.env['project'], 'locations',
                  ctx.properties['location']
              ]),
          'function':
              function_name,
          'labels': {
              # Add the hash of the contents to trigger an update if the bucket
              # object changes
              'content-md5': m.hexdigest()
          },
          'sourceArchiveUrl':
              source_archive_url,
          'environmentVariables': {
              'codeHash': m.hexdigest()
          },
          'entryPoint':
              ctx.properties['entryPoint'],
          'httpsTrigger': {},
          'timeout':
              ctx.properties['timeout'],
          'availableMemoryMb':
              ctx.properties['availableMemoryMb'],
          'runtime':
              ctx.properties['runtime']
      },
      'metadata': {
          'dependsOn': ['upload-function-code']
      }
  }
  resources = [build_step, cloud_function]

  return {
      'resources':
          resources,
      'outputs': [{
          'name': 'sourceArchiveUrl',
          'value': source_archive_url
      }, {
          'name': 'name',
          'value': '$(ref.' + function_name + '.name)'
      }]
  }

Edit

This is in no way a solution to this problem but I found that if I set a bunch of outputs for info I'm interested in, seeing it kind of helps. So I guess you could roll your own sort of log-ish thing by collecting info/output into a list or something in your Python template and then passing all that back as an output- not great but it's better than nothing.

Deployment Manager is an infrastructure deployment service that automates the creation and management of Google Cloud Platform (GCP) resources. What you are trying to do on deployment manager is not possible due to its managed environment.

As of now, the only way to troubleshoot is to rely on the expanded template from the Deployment Manager Dashboard. There is already a feature request in order to address your use case here. I advise you to star the feature request in order to get updates via email and to place a comment in order to show the interest of the community. All the official communication regarding that feature will be posted there.