To set up your environment for developing on Custom Runtime:
Download, install, and then initialize the Cloud SDK.
The Cloud SDK provides you the
gcloudcommand-line tooling for deploying and managing your apps.
By downloading, you agree to be bound by the Terms that govern use of the Cloud SDK for App Engine.
Download and install Git for access to code, samples, libraries, and tools in GitHub:
To locally test and run your App Engine custom runtime apps, download and install Docker:
Don't forget to set up your environment. For example, install a version of your custom runtime and your preferred tooling.