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Lab 1 - Creating an Azure Function Project

Goal

The goal of this lab is to create a basic Azure Function App with an HTTP Trigger function and to trigger the function locally using a REST client.

Steps

1. Create a Function App with a HttpTrigger function

With your IDE of choice create a new Azure Function project (suggested name: XasaOnboarding) with the following options:

  • Azure Functions v3 (.NET Core)
  • HTTP Trigger function
  • Storage Account (AzureWebJobsStorage): Storage Emulator
  • Authentication level: Function

NuGet Packages

First let's have a look at the NuGet packages in the new project, the following packages should be present:

  • Microsoft.NET.Sdk.Functions version 3.0.7.
  • Microsoft.Azure.WebJobs.Extensions.Http version 3.0.2(this is required for using the Http Trigger).

Function code

Now let's have a look at the boilerplate function code. Depending on the IDE, the default Http Trigger function will look something like this:

public static class Function1
{
    [FunctionName("Function1")]
    public static async Task<IActionResult> Run(
        [HttpTrigger(AuthorizationLevel.Function, "get", "post", Route = null)] HttpRequest req,
        ILogger log)
    {
        log.LogInformation("C# HTTP trigger function processed a request.");

        string name = req.Query["name"];

        string requestBody = await new StreamReader(req.Body).ReadToEndAsync();
        dynamic data = JsonConvert.DeserializeObject(requestBody);
        name = name ?? data?.name;

        return name != null
            ? (ActionResult)new OkObjectResult($"Hello, {name}")
            : new BadRequestObjectResult("Please pass a name on the query string or in the request body");
    }
}

Looking at the code, try to answer these questions:

What defines an Azure Function in C#?

How can this function be triggered?

Functions do not need to be static methods anymore, so feel free to remove static from the method and class definitions.

2. Run the Function App locally

Build and run the Function App locally.

The Azure Function Runtime should start in a console window and show some diagnostic information. If there are any issues with your function we will see the errors in this console.

What is the HTTP endpoint the function can be called at?

3. Trigger the HTTP function

With your REST client of choice do a GET request to the local endpoint and provide a value for the name query string parameter.

Does the function return the expected output?

Now place a breakpoint in the function method and execute a GET request again.

Is the breakpoint hit?

4. Create a Copy of the Function

As we've noticed, an Azure Function in C# is a method decorated with the FunctionName attribute. This attribute contains the identifier of the function.

  • Copy the function method and paste it into the same class.
  • Change the method name so it's different from the existing method name.
  • Leave the FunctionName attribute value as it is (so the value in both functions are the same).
  • Now build the project.

What is the build output? Are there errors?

As a best practice, try to limit each class to contain only one function. This way we can use nameof(ClassName) as the FunctionName variable:

public class EchoFunctionHttpTrigger
{
    [FunctionName(nameof(EchoFunctionHttpTrigger))]
    ...
}

If everything works as expected, continue with the next lab to change this default function into something useful.