GCP exercise

The terraform files in this repository create a basic python application with Flask and runs it in Google Cloud Platform App Engine.

It runs a Python Flask application that shows "Hello World" on the webpage. The zip file under the app/ folder contains the source code of the application, which is for demonstration purposes only.

I also created a module to deploy the application because I thought initially that I could create multiple App Engine applications in different regions, but it's not possible. A new project would need to be created on another region and a new App Engine deployment should be made for high availability, using Cloud CDN to re-route traffic to the available region.

Initial Google config

• Clone this repo
• Create a new project in your GCP console
• Manually create a bucket for the terraform state.
• Enable Google App Engine API here
• Create a service account to start the terraform setup here
• Create and download an API key for this service account
• Set the environment variable GOOGLE_CREDENTIALS with the path to the JSON file containing the service account API key

Authenticating to GCP with a service account and a credentials file is not ideal. The users should be properly authenticated to Google using their own credentials, associated with an IAM role.

Configure terraform

• Add the correct parameters to the variables.tf file:

• project-id: The Project ID within GCP that you just created for this exercise
• region: Where the bucket will be created
• location: Where the application will run from
• app_bucket_name: Where the application will be uploaded so that App Engine can be instantiated.

• Run terraform init

In the real world, the application would be deployed from another repository using more robust tools for CI/CD, running test suites, etc.

Build the infra and app

• Run terraform plan -out=/tmp/tf.plan in the root folder of the repo
• Run terraform apply /tmp/tf.plan to deploy the whole infra and the application
• Run terraform state show google_app_engine_application.app | grep default_hostname to see the URL that the application has been deployed.

In the real world, a custom domain would be created and associated via CNAME to this App Engine URL.

Destroy the infra

• Run terraform destroy and proceed to shutdown your GCP project settings

Common GCP Fails

1. The Frankfurt region (europe-west3) doesn't have a lot of capacity.

ERROR: (gcloud.app.deploy) Error Response: [8] The region europe-west3 does not have enough resources available to fulfill the request. Please try again later.

2. App Engine Flexible is not very reliable

google_app_engine_flexible_app_version.hello: Still creating... [9m50s elapsed]

Error: Error creating FlexibleAppVersion: googleapi: Error 500: Internal error encountered.

and another (at least it didn't take almost 10 minutes as the one above):

google_app_engine_application.app: Creation complete after 14s [id=<redacted>]

Error: Error creating StandardAppVersion: googleapi: Error 404: Unable to retrieve P4SA: [service-562739294791@gcp-gae-service.iam.gserviceaccount.com] from GAIA. Could be GAIA propagation delay or request from deleted apps.