Configuring settings

This section uses code in the5-logging directory. Edit the filesand run commands in this directory.

1. Open theconfig.py file for editing and replace the following values:
• Set the value of[PROJECT_ID] to your project ID, which is visible in the Google Cloud console.
• Set the value of[DATA_BACKEND] to the same value you used during theUsing structured data tutorial.
• If you are using Cloud SQL or MongoDB, set the values under theCloud SQL orMongo section to the same values you used during theUsing structured data step.
• Set the value of[CLOUD_STORAGE_BUCKET] to your Cloud Storage bucket name.

• Under theOAuth2 configuration section, set the values of[GOOGLE_OAUTH2_CLIENT_ID] and[GOOGLE_OAUTH2_CLIENT_SECRET] to the application client ID and secret that you created previously.

2. Save and close theconfig.py file.

If you are using Cloud SQL:

1. Open theapp.yaml file for editing.
2. Set the value ofcloudsql-instance to the same value used for[CLOUDSQL_CONNECTION_NAME] in theconfig.py file. Use the formatproject:region:cloudsql-instance. Uncomment this entire line.
3. Save and close theapp.yaml file.

Installing dependencies

To create a virtual environment and install dependencies, use the followingcommands:

virtualenv-ppython3envsourceenv/bin/activatepipinstall-rrequirements.txt

virtualenv-ppython3envenv\scripts\activatepipinstall-rrequirements.txt

Running the app on your local machine

1. Start a local web server:

   pythonmain.py

2. In your browser, enter the following address:

   http://localhost:8080

PressControl+C to exit the worker and then the local web server.

Deploying the app to the App Engine flexible environment

1. Deploy the sample app:

   gcloudappdeploy

2. In your browser, enter the following URL:

   https://PROJECT_ID.REGION_ID.r.appspot.com

   Replace the following:

   • PROJECT_ID: Your Google Cloud project ID
   • REGION_ID: Acode that App Engine assignsto your app

If you update your app, you deploy the updated version by entering the samecommand that you used to deploy the app. The deployment creates a new versionof your app and promotes it to the default version. The earlier versions of yourapp remain, as do their associated virtual machine (VM) instances. All of theseapp versions and VM instances are billable resources. To reduce costs, delete thenon-default versions of your app.

To delete an app version:

1. In the Google Cloud console, go to theVersions page for App Engine.

   Go to Versions

2. Select the checkbox for the non-default app version that you want to delete.Note: The only way you can delete the default version of your App Engine app is by deleting your project. However, you canstop the default version in the Google Cloud console. This action shuts down all instances associated with the version. You can restart these instances later if needed.

   In the App Engine standard environment, you can stop the default version only if your app has manual or basic scaling.

3. To delete the app version, clickdeleteDelete.

For more information about cleaning up billable resources, see theCleaning up section in the final step of this tutorial.

Simulate an error

To see Error Reporting in action, intentionally introduce a mistake inyour code, and then look for the exception in the Google Cloud console'sError Reporting page.

1. Inbookshelf/crud.py, add an operation that accesses an undefined variableand generates aReferenceError in the index view.

   @crud.route("/")deflist():x[3]

2. Deploy the app.

   gcloudappdeploy

3. Access the index page.

   gcloudappbrowse

   You can view the messageAn internal error occurred.

4. In the Google Cloud console, go to theError Reporting page:

   Go toError Reporting

   You can also find this page by using the search bar.

   You can see the error listed.

   

5. Click the error to see information about the error, such as when the errorwas last seen,the number of times the error occurred, a histogram ofoccurrence times, and the stack trace.

Understanding the code

To report uncaught exceptions, the code first uses the Flaskerrorhandlerdecorator, and then reports the exception to Error Reporting by usingtheCloud Client Libraries for Python.

@app.errorhandler(500)defserver_error(e):client=error_reporting.Client(app.config['PROJECT_ID'])client.report_exception(http_context=error_reporting.build_flask_context(request))return"""    An internal error occurred.    """,500

The client automatically adds the traceback info and uses a helper function toextract the relevant request details from the Flask request, which populatesError Reporting with the relevant stack traces and HTTP contexts for anyuncaughtInternalServerErrorHTTP 500 exception in your app.