Does google app engine support environment variables?

Years have passed, and still it doesn't.

My workaround is to compile app.yaml during deployment process (locally or with CI). For example, I have a template file app.tml.yaml file

runtime: python37
handlers:
- url: /static
  static_dir: app/static/
- url: /.*
  script: auto
env_variables:
  DJANGO_GC_DATABASE_PASSWORD: ${DJANGO_GC_DATABASE_PASSWORD}

Then I call envsubst right before deployment envsubst < ./app.tml.yaml > app.yaml and after that gcloud app deploy as usual. After the deployment is done app.yaml with sensitive data is deleted. Variables are read from local .env file or are set in CI system.

There also other approaches I found listed in this post: https://dev.to/mungell/google-cloud-app-engine-environment-variables-5990 but for me they are not convienient or generic enough.

Environment variables can be defined in your application's app.yaml

An example for a python/php/(maybe go?) app. Java uses a different format.

env_variables:
  MY_ENV_VAR: 'some value here'

https://cloud.google.com/appengine/docs/python/config/appconfig#Python_app_yaml_Defining_environment_variables

You can set these values during your CI process as well if you need to by programmatically appending them to your app.yaml before deploying.