App Engine

• App Engine
  • App Engine Standard Environment
  • App Engine Flexible Environment
  • App Engine Standard vs Flexible Comparison
  • App Engine Config Files
  • App Engine IAM Roles

App Engine Standard Environment

• Offers a simple deployment experience compare to the Flexible Environment
• Offers fined-grained autoscaling
• Offers free daily usage quota (low usage service may run at no charge)
• Google provides several SDKs for development and deployment on AppEngine. We can test the application locally before uploading it to the AppEngine Service
• AppEngine runtimes: specific versions of Java, PHP, Python and Go
• For other languages we may want to consider the Flexible Environment
• Sandbox: software construct independent of the hardware. Constraints:
  • No writing to local files
  • All requests time out at 60 seconds
  • Limits in third-party software

App Engine Flexible Environment

• Instead of the sandbox, we can specify the contain the App Engine is running on
• App Engine manages the containers, we get to chose where they are running
• App Engine applications can access GC services such as data stores, memory caches, task queues, etc.

App Engine Standard vs Flexible Comparison

	App Engine Standard	App Engine Flexible
Instance startup	Milliseconds	Minutes
SSH access	No	Yes (not by default)
Write to local disk	No	Yes (ephemeral writes only)
Support 3rd party binaries	No	Yes
Network Access	Via App Engine services	Yes
Pricing Model	After free daily use, pay per instance class, with automatic shutdown	Pay for resource allocation per hour, no automatic shutdown

App Engine Config Files

• app.yaml: defines our configuration settings for our runtime as well as general app, network, and other resource settings
• cron.yaml: a cron.yaml file should in the root directory of your application (alongside app.yaml) and configures scheduled tasks for our applications
• dispatch.yaml: allows us to override routing rules. We can use the dispatch.yaml to send incoming requests to a specific service (formerly known as modules) based on the path or hostname in the URL
• index.yaml: we can use Firestore in Datastore mode (Datastore) for storing data for our applications that run in the flexible environment. We define indexes our app needs in a index.yaml configuration file

App Engine IAM Roles

• App Engine Admin (roles/appengine.appAdmin):
  • Read/Write/Modify access to all application configuration and settings
  • To deploy new versions, a principal must have the Service Account User (roles/iam.serviceAccountUser) role on the App Engine default service account, and the Cloud Build Editor (roles/cloudbuild.builds.editor) and Cloud Storage Object Admin (roles/storage.objectAdmin) roles on the project
• App Engine Creator (roles/appengine.appCreator):
  • Ability to create the App Engine resource for the project
• App Engine Viewer (roles/appengine.appViewer):
  • Read-only access to all application configuration and settings
• App Engine Code Viewer (roles/appengine.codeViewer):
  • Read-only access to all application configuration, settings, and deployed source code
• App Engine Deployer (roles/appengine.deployer):
  • Read-only access to all application configuration and settings
  • To deploy new versions, you must also have the Service Account User (roles/iam.serviceAccountUser) role on the App Engine default service account, and the Cloud Build Editor (roles/cloudbuild.builds.editor) and Cloud Storage Object Admin (roles/storage.objectAdmin) roles on the project
  • Cannot modify existing versions other than deleting versions that are not receiving traffic
• App Engine Service Admin (roles/appengine.serviceAdmin):
  • Read-only access to all application configuration and settings
  • Write access to module-level and version-level settings. Cannot deploy a new version