How to re-use/substitute a variable in app.yaml file using App Engine on Google Cloud Platform

Question

I want to define "my_instance_name" once and re-use it in my app.yaml and index.php

My initial thought was to create an env_variable, but could not find a way to use it: env_variables: CLOUD_SQL_INSTANCE_MAIN: "my_instance_name" beta_settings: cloud_sql_instances: ?CLOUD_SQL_INSTANCE_MAIN?

Then I looked up how to define and reuse variables in yaml files via define: define: &background_color '#998088' fill-color: *background_color

But when I deployed my app, I got a parsing error that said 'Anchors not supported in this handler'

Not sure what the right way to approach this is.

Here's an example of the app.yaml I tried:

runtime: php
env: flex

runtime_config:
    document_root: .

# dsd want to be able to create an env_var for this because
#   this instance name is used here and in index.php
#env_variables:
#  CLOUD_SQL_INSTANCE_MAIN: "my_unique_id:us-central1:main-instance"

beta_settings:
    cloud_sql_instances: "my_unique_id:us-central1:main-instance"

Answer 1

Change your app.yaml as below:

runtime: php
env: flex

runtime_config:
    document_root: .

env_variables:
  CLOUD_SQL_INSTANCE_MAIN: &Instance_main
    "my_unique_id:us-central1:main-instance"

beta_settings:
    cloud_sql_instances: *Instance_main

Reference: Introducing YAML anchors