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How to build AWS Lambda functions in .NET Core

Serverless computing has gained recognition in the previous few years primarily as a result of it helps each ease of growth and excessive scalability. Serverless capabilities are stateless, event-driven, and extremely scalable, and so they don’t have any dependencies on the underlying infrastructure. AWS Lambda is the main instance of a serverless computing platform.

On this article, we’ll discuss how we will use .NET Core to construct and deploy serverless capabilities on AWS Lambda. To work with the code examples supplied on this article, it is best to have Visible Studio 2019 put in in your system. Should you don’t have already got a replica, you’ll be able to download Visual Studio 2019 here. As well as, you will have the AWS Toolkit for Visible Studio 2019, which you’ll be able to download here.

Naturally, you must also have an AWS account since we’ll be constructing and deploying our serverless capabilities to AWS Lambda. Should you don’t have an AWS account, you’ll be able to create a free one here.

AWS Lambda venture sorts in Visible Studio

The AWS Toolkit for Visible Studio 2019 consists of two .NET Core venture templates that may assist you to construct and deploy .NET Core-based AWS Lambda capabilities rapidly. When working with AWS Lambda in Visible Studio, you’ll be able to select from both of two venture sorts:

  1. AWS Lambda venture: Choose the AWS Lambda venture sort if you wish to construct and deploy a person AWS Lambda perform. We’ll leverage the AWS Lambda venture sort on this article to develop and deploy an AWS Lambda perform.
  2. AWS Serverless Software venture: Choose the AWS Serverless Software venture sort for those who’re growing a number of AWS Lambda capabilities that you’ll deploy collectively as a part of an software, utilizing an AWS CloudFormation template to orchestrate the deployment. For instance, you may use this venture sort to create a database, add IAM roles, deploy a number of capabilities concurrently.

Create a brand new AWS Lambda venture in Visible Studio 2019

So let’s create an AWS Lambda venture in Visible Studio 2019. Observe these steps to create a brand new AWS Lambda venture leveraging .NET Core in Visible Studio 2019.

  1. Launch the Visible Studio IDE.
  2. Click on on “Create a brand new venture.”
  3. Within the “Create a brand new venture” window, seek for and choose the AWS Lambda Challenge (.NET Core – C#) template from the checklist of templates displayed.
  4. Click on Subsequent.
  5. Within the “Configure your new venture” window, specify the identify and placement for the brand new venture.
  6. Optionally verify the “Place resolution and venture in the identical listing” verify field, relying in your preferences.
  7. Click on Create.
  8. Choose the Empty Operate blueprint. (See Determine 1.)
  9. Click on End.
aws lambda net core 01 IDG

The AWS Toolkit for Visible Studio supplies numerous quickstart blueprints for AWS Lambda initiatives.

A brand new AWS Lambda venture shall be created. Word that the venture features a file named Operate.cs that accommodates the next code.

utilizing Amazon.Lambda.Core;
[meeting: LambdaSerializer(typeof(Amazon.Lambda.Serialization.
           SystemTextJson.DefaultLambdaJsonSerializer))]
namespace IDGAWSLambda

We’ll work with this code to create our AWS Lambda perform within the subsequent sections of this text.

How does an AWS Lambda perform work?

When working with AWS Lambda capabilities, you’ll usually come throughout two key elements — the perform handler and the context object.

The perform handler is the entry level to begin the execution of your Lambda perform. The perform handler accepts two parameters — enter information as the primary parameter and the Lambda context because the second parameter. Word that Lambda capabilities might be invoked synchronously or asynchronously. In case your Lambda capabilities are long-running, it would be best to make the most of asynchronous invocation.

The context object contains information pertaining to the invocation, i.e. the strategy of invocation in addition to the execution state. This data is handed to the perform handler on the time of execution. For instance, you’ll be able to make the most of the context to verify particulars on the reminiscence allocation or retrieve the variety of milliseconds remaining earlier than the execution of the perform occasions out.

Create a easy Lambda perform in Visible Studio 2019

Check with the Operate.cs file containing the Operate class that was routinely created together with your new AWS Lambda venture. Change the code of the Operate.cs file with the next code:

utilizing Amazon.Lambda.Core;
[assembly: LambdaSerializer(typeof(Amazon.Lambda.Serialization.SystemTextJson.DefaultLambdaJsonSerializer))]
namespace IDGAWSLambda
{
    public class Operate
   
}

As you’ll be able to see, our super-simple perform takes a string as enter and returns the string prefixed by “Welcome: ”.

Deploy the Lambda perform to AWS Lambda

You may deploy an AWS Lambda perform in two alternative ways, both by utilizing the AWS Toolkit for Visible Studio or by utilizing the AWS Console. On this instance, we’ll use the AWS Toolkit to deploy our Lambda perform.

Observe the steps outlined beneath to deploy the perform to AWS Lambda.

  1. Proper-click on the venture within the Answer Explorer window.
  2. Click on “Publish to AWS Lambda…”
  3. Within the “Add to AWS Lambda” display screen, you’ll be able to specify the perform identify, description, the framework, the Lambda runtime model, meeting identify, sort identify, technique identify, and so on. All of those shall be populated routinely, however you’ll be able to change them if desired. (See Determine 2.)
  4. Click on Subsequent.
  5. Within the “Superior Operate Particulars” display screen, you’ll be able to specify the IAM position to permit your Lambda perform to entry AWS providers resembling S3.
  6. Click on Add.
aws lambda net core 02 IDG

Determine 2: The small print about your Lambda perform shall be populated routinely however you’ll be able to change them.

As soon as the deployment is profitable, you’ll be offered with a Operate View display screen. Once you enter a string right here and click on Invoke, you’ll see the next output:

aws lambda net core 03 IDG

Determine three: Our easy AWS Lambda perform in motion.

Retrieve data from the Lambda perform’s context object

The next code snippet illustrates how one can write a Lambda perform that may return data from the context object such because the request Id, perform identify, perform model, remaining time, and reminiscence restrict.

public string FunctionHandler(ILambdaContext context)

Check your Lambda perform from the AWS Administration Console

Now you can take a look at the Lambda perform from the AWS Administration Console by following the steps outlined beneath.

  1. Within the AWS Administration Console, click on on All Companies -> Lambda.
  2. From the checklist of Lambda capabilities displayed, choose the perform you’d like to check (the identify of the perform is “Operate” in our instance).
  3. Within the subsequent display screen, choose the Check tab.
  4. Click on Check to execute the Lambda perform.
aws lambda net core 04 IDG

Determine four: Displaying data from the context object of our easy Lambda perform.

The fantastic thing about serverless capabilities is that they’re straightforward to create and you needn’t be involved concerning the underlying infrastructure. You may give attention to constructing your capabilities with out worrying about OS-level patching, community connectivity, managing and sustaining digital machines, or scaling thresholds.

You should utilize .NET Core and C# to develop serverless capabilities for AWS Lambda, Microsoft Azure Capabilities, or Google Cloud Capabilities. I’ll write extra about utilizing .NET Core and C# for serverless computing in my future posts right here.

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