A Go 1.11 app in App Engine is configured using an app.yaml 
file, that contains the runtime, handlers, scaling, and other general settings
including environment variables.
About app.yaml 
files
 
You can specify the runtime configuration for your Go 1.11 app,
including versions and URLs, in the app.yaml 
file. This file acts as a
deployment descriptor of a specific service 
version. You must first create the app.yaml 
file for the default 
service of your app
before you can create and deploy app.yaml 
files for additional services.
Generally, your app.yaml 
file requires only the runtime 
element for a simple
Go 1.11 app in the standard environment, for
example:
  runtime 
 : 
  
 go111 
 
 
app.yaml 
files in your
app, see Structuring Web Services 
. App Engine provides default values for all other settings, including the F1 instance class , which determines the memory and CPU resources that are available to your app, and automatic scaling , which controls how and when new instances of your app are created.
If you need to override the default settings, create an app.yaml 
file and
specify the settings you need. For more information, see  app.yaml 
file reference 
.
You can specify a unique name for your app.yaml 
files, but then you must
specify the file name with the deployment
command 
as well. For example, if you name your app.yaml 
file service-name-app.yaml 
or app.standard.yaml 
, then you must deploy your app using either:
  gcloud app deploy service-name-app.yaml 
 gcloud app deploy app.standard.yaml 
 
 
All configuration elements
For a complete list of all the supported elements in this configuration file,
see the  app.yaml 
reference 
.

