What should you do?

Topic 3, City Power & Light

Case study

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Background

City Power & Light company provides electrical infrastructure monitoring solutions for homes and businesses. The company is migrating solutions to Azure.

Current environment

Architecture overview

The company has a public website located at http://www.cpandl.com/. The site is a single-page web application that runs in Azure App Service on Linux. The website uses files stored in Azure Storage and cached in Azure Content Delivery Network (CDN) to serve static content.

API Management and Azure Function App functions are used to process and store data in Azure Database for PostgreSQL. API Management is used to broker communications to the Azure Function app functions for Logic app integration. Logic apps are used to orchestrate the data processing while Service Bus and Event Grid handle messaging and events.

The solution uses Application Insights, Azure Monitor, and Azure Key Vault.

Architecture diagram

The company has several applications and services that support their business. The company plans to implement serverless computing where possible.

The overall architecture is shown below.

User authentication

The following steps detail the user authentication process:

✑ The user selects Sign in in the website.

✑ The browser redirects the user to the Azure Active Directory (Azure AD) sign in page.

✑ The user signs in.

✑ Azure AD redirects the user’s session back to the web application. The URL includes an access token.

✑ The web application calls an API and includes the access token in the authentication header. The application ID is sent as the audience (‘aud’) claim in the access token.

✑ The back-end API validates the access token.

Requirements

Corporate website

✑ Communications and content must be secured by using SSL.

✑ Communications must use HTTPS.

✑ Data must be replicated to a secondary region and three availability zones.

✑ Data storage costs must be minimized.

Azure Database for PostgreSQL

The database connection string is stored in Azure Key Vault with the following attributes:

✑ Azure Key Vault name: cpandlkeyvault

✑ Secret name: PostgreSQLConn

✑ Id: 80df3e46ffcd4f1cb187f79905e9a1e8

The connection information is updated frequently. The application must always use the latest information to connect to the database.

Azure Service Bus and Azure Event Grid

✑ Azure Event Grid must use Azure Service Bus for queue-based load leveling.

✑ Events in Azure Event Grid must be routed directly to Service Bus queues for use in buffering.

✑ Events from Azure Service Bus and other Azure services must continue to be routed to Azure Event Grid for processing.

Security

✑ All SSL certificates and credentials must be stored in Azure Key Vault.

✑ File access must restrict access by IP, protocol, and Azure AD rights.

✑ All user accounts and processes must receive only those privileges which are essential to perform their intended function.

Compliance

Auditing of the file updates and transfers must be enabled to comply with General Data Protection Regulation (GDPR). The file updates must be read-only, stored in the order in which they occurred, include only create, update, delete, and copy operations, and be retained for compliance reasons.

Issues

Corporate website

While testing the site, the following error message displays:

CryptographicException: The system cannot find the file specified.

Function app

You perform local testing for the RequestUserApproval function. The following error

message displays:

‘Timeout value of 00:10:00 exceeded by function: RequestUserApproval’

The same error message displays when you test the function in an Azure development environment when you run the following Kusto query: FunctionAppLogs

| where FunctionName = = "RequestUserApproval"

Logic app

You test the Logic app in a development environment. The following error message displays:

‘400 Bad Request’

Troubleshooting of the error shows an HttpTrigger action to call the RequestUserApproval function.

Code

Corporate website

Security.cs:

Function app

RequestUserApproval.cs:

You need to correct the RequestUserApproval Function app error.

What should you do?
A . Update line RA13 to use the async keyword and return an HttpRequest object value.
B . Configure the Function app to use an App Service hosting plan. Enable the Always On setting of the hosting plan.
C . Update the function to be stateful by using Durable Functions to process the request payload.
D . Update the functionTimeout property of the host.json project file to 15 minutes.

View Answer

Answer: C

Explanation:

Async operation tracking

The HTTP response mentioned previously is designed to help implement long-running HTTP async APIs with Durable Functions. This pattern is sometimes referred to as the polling consumer pattern.

Both the client and server implementations of this pattern are built into the Durable Functions HTTP APIs.

Function app

You perform local testing for the RequestUserApproval function. The following error message displays:

‘Timeout value of 00:10:00 exceeded by function: RequestUserApproval’

The same error message displays when you test the function in an Azure development environment when you run the following Kusto query:

FunctionAppLogs

| where FunctionName = = "RequestUserApproval"

Reference: https://docs.microsoft.com/en-us/azure/azure-functions/durable/durable-functions-http-features