Reporting errors

Configuring settings

This section uses code in the 5-logging directory. Edit the files and run commands in this directory.

1. Open the config.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 the Using structured data tutorial.
• If you are using Cloud SQL or MongoDB, set the values under the Cloud SQL or Mongo section to the same values you used during the Using structured data step.
• Set the value of [CLOUD_STORAGE_BUCKET] to your Cloud Storage bucket name.

• Under the OAuth2 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 the config.py file.

If you are using Cloud SQL:

1. Open the app.yaml file for editing.
2. Set the value of cloudsql-instance to the same value used for [CLOUDSQL_CONNECTION_NAME] in the config.py file. Use the format project:region:cloudsql-instance . Uncomment this entire line.
3. Save and close the app.yaml file.

Installing dependencies

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

  virtualenv 
 - 
 p 
 python3 
 env 
 source 
 env 
 / 
 bin 
 / 
 activate 
 pip 
 install 
 - 
 r 
 requirements 
 . 
 txt 
 

  virtualenv 
 - 
 p 
 python3 
 env 
 env 
\ scripts 
\ activate 
 pip 
 install 
 - 
 r 
 requirements 
 . 
 txt 
 

Running the app on your local machine

1. Start a local web server:

     python 
    main 
    . 
    py 
    
   

2. In your browser, enter the following address:

    http://localhost:8080 
   

Press Control+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:

     gcloud 
    app 
    deploy 
    
   

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 : A code that App Engine assigns to your app

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

To delete an app version:

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

   Go to Versions

2. Select the checkbox for the non-default app version that you want to delete.
3. To delete the app version, click delete Delete .

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

Simulate an error

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

1. In bookshelf/crud.py , add an operation that accesses an undefined variable and generates a ReferenceError in the index view.

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

2. Deploy the app.

   gcloud  
   app  
   deploy

3. Access the index page.

   gcloud  
   app  
   browse

   You can view the message An internal error occurred .

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

   Go to Error 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 error was last seen,the number of times the error occurred, a histogram of occurrence times, and the stack trace.

Understanding the code

To report uncaught exceptions, the code first uses the Flask errorhandler decorator, and then reports the exception to Error Reporting by using the Cloud Client Libraries for Python .

  @app 
 . 
 errorhandler 
 ( 
 500 
 ) 
 def 
  
 server_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 to extract the relevant request details from the Flask request, which populates Error Reporting with the relevant stack traces and HTTP contexts for any uncaught InternalServerError HTTP 500 exception in your app.