Serverless

01: Before Starting

In this tutorial, we will explore Azure server less offering Azure Function. Please read the pre-requisite as below before starting. This tutorial expect you to know what is server less computing. Familiarity with Python and Flask framework. Azure Subscription Azure CLI installed on your machine VS Code as an IDE. Account on github.com At the end of this tutorial, you will be able to design a service in Azure Function with concept of API Authentication, Logging and Telemetry, Configuring Azure Function for popular python framework like Flask or FastAPI.

October 1, 2022 Read

02: Setting up Environment

Browser Login to Azure Portal with your account. Select your subscription. Say: Visual Studio Enterprise Subscription. Create a new Resource Group. Name: az-func-demo-wus Region: West US AZ CLI Authenticate az cli. Select your account when prompted az login Set Account to Visual Studio Enterprise Subscription. Copy subscription Id from portal. az account set --subscription xxx-0fc2-xxxxx-9342-xxxxxxx GitHub Repo Create a GitHub repo on github.com for committing the code. Click on github.com Create a new public repository.

October 1, 2022 Read

03: Creating Azure Function App

For this tutorial, we will create azure function using Azure Portal, however, this can also be created directly from VSCode, Az Cli etc. Creating Azure Function App using Azure Portal Select resource group az-func-demo-wus Click on +Create button in overview tab. Search for Function App in marketplace and click create In Create Function App page: Ensure right subscription and resource group are selected. Function App name: Provide a unique name to Azure Function.

October 1, 2022 Read

04: Writing an API

Now we have Azure Function App with a Function (API) running. Lets us know write our API. There is no set rules or patterns to develop APIs on Azure Function App. One can have one-function-one-api or we can use popular framework like Flask or FastApi integrated with Azure Function. For this tutorial we will use Flask as that can help us migrate existing Flask App running on Virtual Machine or any Host to Azure Function.

October 1, 2022 Read

05: API Authentication

As we now have a function integrated with flask framework and exposing two APIs i.e. /health and /vault/<secret_name>. In this step, we will see who to have protected api. If we just need to protect all APIs then we can simply use Azure Function Identity feature, however in most cases, not all api’s needs Authz as we may have health api which needs to be open. Also, in many other cases we want to verify token for custom roles based on access to certain specific api.

October 1, 2022 Read

06: Accessing Protected API

To access protected API in our Function App, we need to get an access token from Azure AD App. This diagram shows a high-level view of the authentication flow: The E2E oauth2 auth code flow is being described here Generate Client Id and Secret To generate an access token to access our APIs, A User first need to onboard their AD App (Client AD App) to our AD App (Server AD App).

October 1, 2022 Read

07: Logging with App Insight

Before we start, we need to verify if Azure Function App is connected to an instance of App Insight or not. To check this, go to Application Insights in Azure Function and verify if it is connected to an App Insight Resource. If not, we either need to create a new App Insight resource and attach it to Function App or use an existing App Insight app. Get App Insight Connection String Click on App Insight attached to Azure Function Copy Instrumentation Key and Connection String from overview tab Code Changes Notes:

October 1, 2022 Read

08: Telemetry with App Insight

Let us now create work on injestig code for App Insight telemetry. This help observe how a request was served from the different part of the code. Code Changes In src/appinsight/logger.py, we will create decorator that help inject trace to App Insight def trace_as_dependency(tracer: Tracer = None, name: str = None, prefix: str = None): """trace_as_dependency [method decorator to trace a method invocation as a dependency (in AppInsights)] Args: tracer (Tracer): [Opencensus tracer object used to create the trace record.

October 1, 2022 Read