Functions are a serverless compute platform - you supply the code and you don’t need to provision infrastructure or manage scale. Functions get triggered in response to events, which could be a file being uploaded in Blob storage or an incoming HTTP request.
Azure Functions are hosted in a Functions App which is a type of App Service (like Web Apps). Function Apps are part of an App Service Plan but they can use a consumption model, which means infrastructure is only provisioned and paid for while functions are running, there is no cost when there’s no activity.
In this lab we’ll get started with a simple function triggered from an HTTP call, and see how to run it locally and in Azure.
Open the Portal and create a new resource. Search for ‘function’, select Function app and Create. There are some interesting options:
Go ahead and create the new Function App, creating a new RG and Storage Account to use
If you create a Function App in the Portal, you can edit code directly in the browser. Open Functions from the left menu and click Create:
When the function is created, switch to the Code + Test menu. Can you run your function from here? Edit the response the function sends back and save it. Browse to the URL - can you call the function from the browser?
You can delete the RG for the Portal function when you’ve finished exploring.
The Portal is great for experimenting, but for anything other than a playground we’ll want function code in source control. Azure Functions have a custom CLI you use to create projects, run functions on your local machine and deploy to Azure.
First we need to install the Azure Functions Core Tools (using Homebrew on the Mac or Chocolatey on Windows):
# Windows:
choco install azure-functions-core-tools
# macOS:
brew tap azure/functions
brew install azure-functions-core-tools@4
There are other installers available - be sure to install the v4 option for your OS.
Check your installation:
func --version
The output should show you’re on version 4 (mine is 4.0.4829 but yours might be newer).
There is a .NET function library with an HTTP trigger in the calendar folder:
You can use the func CLI to run the function locally:
cd labs/functions/http/calendar
func start
You’ll see output from the .NET build, and then a line saying the function is listening on localhost
Try it:
curl http://localhost:7071/api/HttpTime
This is great for a short feedback loop. You can test the functionality without waiting for an Azure deployment, make changes and run func start again to test them before you go live.
That one command is all you need to run functions locally :) Next we’ll deploy to Azure.
In Azure we’ll need to create the pre-requisites - a Resource Group and Storage Account:
# find a location near you which supports serverless functions:
az functionapp list-consumption-locations -o table
# create the RG:
az group create -n labs-functions-http --tags courselabs=azure -l eastus
# and storage account - use the region you want for your function:
az storage account create -g labs-functions-http --sku Standard_LRS -l eastus -n <sa-name>
📋 Create a Function App to host the function, using the az functionapp create command. Choose .NET as the runtime and Functions version 4. Select your region for the consumption-plan and link it to the Storage Account you just created.
Not sure how?</summary>
Check the help text:
az functionapp create --help
The flag for the region is different from usual, because you specify the consumption plan and location in one:
az functionapp create -g labs-functions-http --runtime dotnet --functions-version 4 --consumption-plan-location eastus --storage-account <sa-name> -n <function-name>
</details>
Check in the Portal - you’ve got an app service plan with no scale up or scale out options, this is the serverless (consumption) plan. You can see the function app:
Now you can deploy from the functions CLI direct to Azure:
func azure functionapp publish <function-name>
You’ll see the app compiled locally and uploaded
The output includes the public URL for the function. This one uses anonymous authorization, so you can test it with:
curl <public-url>/api/HttpTime
Check the storage account in the Portal. You’ll see blob containers are locked, but file storage is available to view. This is the root filesystem for the app; can you find the application logs?
One Function App can host multiple functions - typically you group together all the functions for a project into one Function App.
We have some more functions we can add in the update folder:
update/HttpDate.cs - HTTP trigger which responds with the current date
update/HttpDay.cs - HTTP trigger which responds with the current day of the week
# check you're still in the calendar folder:
pwd
# copy the new functions to this folder:
cp ../update/*.cs .
# start the function emulator:
func start
Now the new functions are in the project folder, you’ll see three HTTP functions listed
The name of the function in the code becomes the URL path to call for an HTTP trigger.
Test the new functions:
curl http://localhost:7071/api/HttpDate
curl http://localhost:7071/api/HttpDay
📋 Deploy the updated functions to Azure.
Not sure how?</summary>
The new functions are in your local project, so it’s the same publish command:
func azure functionapp publish <function-name>
</details>
Try some of the functions when they’re deployed:
curl <public-url>/api/HttpTime
curl <public-url>/api/HttpDate
Check in the Portal - you still have one Function App in the Plan. Open it and you can see the individual Functions. Open one and check the menu options - Integration shows you the triggers, inputs and outputs; Monitor shows you the recent runs and results, click one to see the logs.
Try the other new function:
curl -i <public-url>/api/HttpDay
Youll get a Not authorized error because this function requires authentication
📋 Browse the function options in the Portal to find an authentication key, so you can call the HttpDay function with curl.
Not sure how?</summary>
Back in the Portal open the function click Get function URL - here the output includes a key, also shown in Function Keys. The Portal adds the key because the function is set with authorization required.
Your URL with the token will look something like this:
curl https://courselabsazes.azurewebsites.net/api/HttpDay?code=UUGtEqCqMqF-whsqFzfaafajkURTOgXqVS1lZ9eepgHIXvObgAzFuJ2bGVA==
</details>
The structure of functions is the same as other App Services:
The big difference with functions is that the App Service Plan can be on the consumpion model, so you don’t need to have any servers running.
Your turn to try this out. Create a new directory and from there create a new function with func new. Choose Powershell as the runtime and pick the HTTP trigger template. Run the function locally - does it work without any code changes? Publish the function to Azure. Can you use your existing Function App to host the new function?
Delete the lab RG:
az group delete -y --no-wait -n labs-functions-http