Starting Go server on App Engine localhost throws error - google-app-engine

Question

Can anyone tell me why this is happening:
$ dev_appserver.py nmg_server
INFO 2017-07-08 17:15:37,369 application_configuration.py:461] No version specified. Generated version id: 20170708t171537
WARNING 2017-07-08 17:15:37,369 application_configuration.py:166] The Managed VMs runtime is deprecated, please consider migrating your application to use the Flexible runtime. See https://cloud.google.com/appengine/docs/flexible/python/migrating for more details.
INFO 2017-07-08 17:15:37,472 devappserver2.py:116] Skipping SDK update check.
INFO 2017-07-08 17:15:37,513 api_server.py:312] Starting API server at: http://localhost:54096
INFO 2017-07-08 17:15:37,517 api_server.py:938] Applying all pending transactions and saving the datastore
INFO 2017-07-08 17:15:37,517 api_server.py:941] Saving search indexes
Traceback (most recent call last):
File "/Users/dgaedcke/gcloud_tools/google-cloud-sdk/platform/google_appengine/dev_appserver.py", line 103, in <module>
_run_file(__file__, globals())
File "/Users/dgaedcke/gcloud_tools/google-cloud-sdk/platform/google_appengine/dev_appserver.py", line 97, in _run_file
execfile(_PATHS.script_file(script_name), globals_)
File "/Users/dgaedcke/gcloud_tools/google-cloud-sdk/platform/google_appengine/google/appengine/tools/devappserver2/devappserver2.py", line 381, in <module>
main()
File "/Users/dgaedcke/gcloud_tools/google-cloud-sdk/platform/google_appengine/google/appengine/tools/devappserver2/devappserver2.py", line 369, in main
dev_server.start(options)
File "/Users/dgaedcke/gcloud_tools/google-cloud-sdk/platform/google_appengine/google/appengine/tools/devappserver2/devappserver2.py", line 196, in start
options.api_host, apiserver.port, wsgi_request_info_, options.grpc_apis)
File "/Users/dgaedcke/gcloud_tools/google-cloud-sdk/platform/google_appengine/google/appengine/tools/devappserver2/dispatcher.py", line 223, in start
_module.start()
File "/Users/dgaedcke/gcloud_tools/google-cloud-sdk/platform/google_appengine/google/appengine/tools/devappserver2/module.py", line 1647, in start
self._add_instance()
File "/Users/dgaedcke/gcloud_tools/google-cloud-sdk/platform/google_appengine/google/appengine/tools/devappserver2/module.py", line 1799, in _add_instance
expect_ready_request=True)
File "/Users/dgaedcke/gcloud_tools/google-cloud-sdk/platform/google_appengine/google/appengine/tools/devappserver2/go_runtime.py", line 189, in new_instance
self._go_application.maybe_build()):
TypeError: maybe_build() takes exactly 2 arguments (1 given)
I'm trying to run my server for testing on localhost and it keeps exiting with this error

Answer 1

This appears to be a bug in Cloud SDK which is affecting dev_appserver.py when using with App Engine Managed VMs. It does not seem to be affecting App Engine Standard or App Engine Flex environments.
Until Google releases a new Cloud SDK with the fix, you can modify the CLOUD_SDK_INSTALL_DIR//platform/google_appengine/google/appengine/tools/devappserver2/go_managedvm.py file locally as shown below (added both the patchable unified diff as well as before/after just for convenience).
Also consider moving to App Engine Flex since Managed VMs are deprecated and will not be supported after October 27, 2017.
Warning: The Managed VMs beta environment (applications deployed with
vm:true) is deprecated and will be decommissioned. This page is for
users who are already using the flexible environment with vm:true in
their app.yaml and want to upgrade to the latest release. If you are
updating your application from the standard environment, see the
Migrating Services from the Standard Environment to the Flexible
Environment instead.
Diff in patchable format
--- /Users/tuxdude/google-cloud-sdk-orig/platform/google_appengine/google/appengine/tools/devappserver2go_managedvm.py 2017-07-08 11:11:11.000000000 -0700
+++ /Users/tuxdude/google-cloud-sdk/platform/google_appengine/google/appengine/tools/devappserver2/go_managedvm.py 2017-07-08 11:11:11.000000000 -0700
## -152,15 +152,9 ##
logging.debug('Build succeeded:\n%s\n%s', stdout, stderr)
self._go_executable = exe_name
- def maybe_build(self, maybe_modified_since_last_build):
+ def maybe_build(self):
"""Builds an executable for the application if necessary.
- Args:
- maybe_modified_since_last_build: True if any files in the application root
- or the GOPATH have changed since the last call to maybe_build, False
- otherwise. This argument is used to decide whether a build is Required
- or not.
-
Returns:
True if compilation was successfully performed (will raise
an exception if compilation was attempted but failed).
## -173,9 +167,6 ##
self._work_dir = tempfile.mkdtemp('appengine-go-bin')
atexit.register(_rmtree, self._work_dir)
- if self._go_executable and not maybe_modified_since_last_build:
- return False
-
if self._go_executable:
logging.debug('Rebuilding Go application due to source modification')
else:
Before:
def maybe_build(self, maybe_modified_since_last_build):
"""Builds an executable for the application if necessary.
Args:
maybe_modified_since_last_build: True if any files in the application root
or the GOPATH have changed since the last call to maybe_build, False
otherwise. This argument is used to decide whether a build is Required
or not.
Returns:
True if compilation was successfully performed (will raise
an exception if compilation was attempted but failed).
False if compilation was not attempted.
Raises:
BuildError: if building the executable fails for any reason.
"""
if not self._work_dir:
self._work_dir = tempfile.mkdtemp('appengine-go-bin')
atexit.register(_rmtree, self._work_dir)
if self._go_executable and not maybe_modified_since_last_build:
return False
if self._go_executable:
logging.debug('Rebuilding Go application due to source modification')
else:
logging.debug('Building Go application')
self._build()
return True
After:
def maybe_build(self):
"""Builds an executable for the application if necessary.
Returns:
True if compilation was successfully performed (will raise
an exception if compilation was attempted but failed).
False if compilation was not attempted.
Raises:
BuildError: if building the executable fails for any reason.
"""
if not self._work_dir:
self._work_dir = tempfile.mkdtemp('appengine-go-bin')
atexit.register(_rmtree, self._work_dir)
if self._go_executable:
logging.debug('Rebuilding Go application due to source modification')
else:
logging.debug('Building Go application')
self._build()
return True