Running Go server on App Engine server localhost throws error

This seems to be a bug in the Cloud SDK that affects dev_appserver.py

when used with App Engine Managed VMs

. This does not seem to affect the App Engine Standard or App Engine Flex environment.

Until Google releases a new Cloud SDK with a fix, you can modify the file locally CLOUD_SDK_INSTALL_DIR//platform/google_appengine/google/appengine/tools/devappserver2/go_managedvm.py

as shown below (added both the fixable unified difference and before / after just for convenience).

Also consider moving to App Engine Flex from Managed Virtual Machines deprecated and will not be supported after October 27, 2017 .

Warning : The beta environment for managed VMs (applications deployed with vm:true

) is out of date and will be retired. This page is for users who are already using a flexible environment with vm:true

in their own app.yaml

and want to upgrade to the latest version. If you're updating your application from a standard environment, see Migrating services from a standard environment to a flexible environment instead .

Diff in patch 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