Getting Started with AWS Lambda

DevOps is about speed. AWS Lambda and serverless architectures allow you to develop and deliver faster than before. When used effectively, they can lower your costs and allow you to embrace DevOps with ease.

Lambda is a serverless computing environment which allows you to connect your code with an event. Your code will be executed when an event fires. You can also put Lambda functions behind a REST API, which we’ll see how to do momentarily.

Lambda supports many different languages and execution environments. For this example, we’ll be using Node.js since it’s pretty simple to get a Lambda function up and running with that environment. You can also use Python, Go, C#, and Java. Let’s create our first Lambda function!

Tools We Need

No need of local development environment, AWS Lambda will execute our code.

Creating your first Lambda function

Select “Lambda” from the “Services” menu. Alternately, you can type “Lambda” in the search box on AWS console and then select it.

Once you’re on the Lambda screen, click the “Create a Function” button to begin the process of creating your first function. Fill out the form as you see it below:

The role field refers to the permissions you want your Lambda function to have within AWS. You can further research AWS Identity and Access Management, but we won’t cover that here. For our purposes, we’ll create a role for our function based on the “Simple Microservice” permissions.

Click the “Create function” button to navigate to the Lambda function creation screen. This screen looks busy at first, so we’ll walk through it piece by piece and set what we need as we go along. For now, close the “Designer” section of the page by clicking on the section header. We will come back to that while integrating our code with another AWS service in order to make it available for use. Your screen should look like this:

In the “Function code” section, you’ll see an integrated code editor for you to use. Let’s use simple example to illustrate working of plumping in AWS lambda. Edit code as below:

exports.handler = (event, context, callback) = {
    const result = event.number1 + event.number2;
    callback(null, result);
};

Let’s test our Lambda function to see if it works. The Lambda interface gives us ability to do that. Click on dropdown next to “Test” and “Save” buttons and choose “configure test events.” (Note: “configure test events” will be your only option.)

In the “Configure Test Event” dialog box, select “Hello World” as the template and update the JSON inside the box to the following:

{
    "number1": 2,
    "number2": 3
}

Once done, your screen should look like this:

Click the “Create” button, and you’re ready to test. What we just did was create a test input to our function. Now we can execute the function and make sure the result is what we expect.

Click the “Save” button if it’s active. Make sure your new test function is selected in the dropdown and click the “Test” button. Your function will execute, and you’ll see the results displayed at the bottom of the page. In this case, the result returned from the function should be 5.

Congratulations! We’ve created a Lambda function and successfully tested it so we can be confident it will do what we think it will do.

So now we have working lambda function. We can invoke it from Events/ Triggers. This event can be many different things, such as database records being updated or files being uploaded to an S3 bucket.

What's Next?

Awesome, you just configured, wrote and executed your first code on AWS Lambda!

What else can you do with Python and Lambda? Stay tuned to Crevise Blogs!

We can understand the real power of AWS Lambda when we connect a trigger to it, so our code will be executed based on the events. We'll take a look at that in the next tutorial.