Getting Started with Azure Functions

Azure functions are Function as a Service (FAAS) offering from Microsoft Azure. It is a serverless compute service from the provider where user need not to worry about underlying deployment infrastructure because Microsoft as a cloud provider manages it for us.

Azure functions are good choice to perform independent stateless task. It has the ability to scale automatically based on traffic/demand. The documentation covers a lot, so we will not go into more details instead lets try to create a simple function.

Triggers – An azure function needs a trigger to perform its task. There are no of inbuilt triggers supported by Azure functions like HTTP Trigger, Queue Trigger, Blog Trigger etc.

Note – An azure function must have one and only one trigger associated to it.

Bindings – Azure function framework provides a way to read data into a function and write data from function to any data service. There are two major types of bindings,

1. Input binding – Read data into an Azure function from any data service.
2. Output binding – Write data to any data service from an Azure function.

Function.json – A file containing configuration details like trigger, bindings with respect to an individual Azure function. Every azure function has a corresponding configuration file that means every function app will have exactly one function.json with respect to each function.

There are multiple ways to create function apps like,

·         Azure Portal

·         Visual Studio

·         CLI

·         VS Code

We will look at the CLI and see that how easy it is to create a function app using Azure Function Core Tools.

Prerequisite:-

• Install Azure Function Core Tools from https://github.com/Azure/azure-functions-core-tools
• Start with an empty folder and cmd/power-shell  instance must be opened from same.

Step 1:- After installing the Core tools as mentioned above lets first verify it. Open a new instance of any command line tool (I am using power-shell but its completely your choice) and run below command,

                func

You should be able to see details like, Core Tool’s version, Contexts, Actions etc as shown below,

Step 2:- Create a new function app. Function app is a unit of deployment or a group of logically related functions, shares common configuration and scale together. Use below command to initialize a new Function App.

func init

There are multiple options worker runtime to select from but lets start with node and JavaScript as language.

Step 3:- Add new function by using command,

                func  new

Lets start with Http trigger template and you can also update function name to one you prefer, but I am leaving it to default. Hit enter,

Step 4:- Run your function app using below command,

                func start

Step 5:- Try hitting the URL from any browser. Please note that the default function generated by CLI expects an input(name) either in query string or request body.