An Azure Function App is the Azure home for one or more Azure Functions. Each function handles a focused task; the app hosts them and provides a place to manage their runtime and configuration. Think of it loosely as the computer running your functions—except Azure handles the underlying infrastructure. That is the practical meaning of “serverless,” not a promise that servers have vanished. section 2.2.14 section 2.2.17
Give uploaded photos a job
In a photo-upload workflow, images arrive in Blob Storage and a function handles image resizing. Create the Function App first, then add a function using the Blob Storage trigger template. Set its path to `imagecontainer/{name}`: the trigger watches that container, and `{name}` identifies the incoming file. A newly created function only logs inserted files until you add the processing work. section 2.2.14 section 2.2.18
To set up the hosting app in the Azure Portal:
- Find Function App, select Add, and choose a hosting plan. Consumption is the option used in this workflow; Consumption, Premium, and an Azure App Service plan are other hosting choices with different trade-offs. section 2.2.16 section 8.6
- Choose the subscription, resource group, name, runtime, version, and region. The photo example uses .NET 8 LTS with the isolated worker model. An app name must be unique because it forms part of the app’s public URL. section 2.2.16 section 2.2.17
- Connect a storage account, preferably in the same region. The app uses storage for such things as trigger and binding metadata, code, and logs; keeping it nearby reduces latency. Enable Application Insights for monitoring, then review and create the app. section 2.2.16 section 2.2.17
For repeatable setup, `az functionapp create` offers a CLI alternative: supply an app name, storage account, resource group, Consumption-plan location, and Functions version. The app’s `host.json` holds settings that affect all its functions, while `local.settings.json` holds local-development settings that are not deployed to Azure. In short, the app is more than a folder for code. section 8.2
The app is also an integration boundary worth checking. Import a Function App into API Management and every function inside it becomes an API endpoint through that integration template—not just the one you had in mind. If a function cannot reach its expected blob containers, inspect the app’s `AzureWebJobsStorage` setting to identify the linked storage account. section 8.4.4
