Create AWS Lambda function

in the browser in order to access the AWS console. After logging in, click "Get Started Now" on the pop-up page after selecting Lambda in the Compute section and selecting the AWS location from the top menu on the right (typically pick a location closest to your location to minimize network latency). You will see a list of current function codes instead of the welcome page if this is not the first function in the chosen region.Simply select "Create a Lambda Function" in this instance.

The next step is to create lambda functions. Set the option to "Edit code inline" and enter the following code in the web console editor according to your chosen runtime environment. AWS Lambda functions are executed in a environment without any visual information. Therefore, all runtimes implement a convenient way to write centralized logs to Amazon CloudWatch.

Amazon CloudWatch is a monitoring and logging service that can be used to manage application metrics, alerts, and logs, as well as AWS services used within the application.In a Node.js environment, anything written with console.log() is redirected to CloudWatch Logs, whereas in Python, any output from print is redirected.

The following is two instances of the Node.js lambda function.

1.

`//Introducing the core modules required for Lambda

const AWS = require('aws-sdk');



// Function for handling Lambda events

exports.handler = async (event, context,callback) => {

    // return result body

    return {

        statusCode: 200,

        body: JSON.stringify({ message: 'Hello, World!' })

    };

};`

2.

`exports.handler = async (event, context,callback) => {

    console.log('lambda event:', JSON.stringify(event, null, 2));

    var name = '';

    if('name' in event ){

        name = ['name'];

        console.log('name = ', event.name)

    }else{

        name = 'world';

        console.log('name = ', name)

    }

    var result = 'Hi,' + name ;

    callback(null, result);

};`

In Node.js, we use the callback to end functions in the standard Node.js programming model. In this case, the function successfully ends with callback(null, data) and returns the greeting string object. If the first parameter of the callback is not null, it indicates that the function encountered an execution error and returns, such as callback(error).

After initialization is complete, the function receives the information provided as event input and the context of the call—both in their native runtime formats: JavaScript objects in Node.js like , event use case is like this .

It is recommended to start with the Getting Started link in the documentation to create an AWS IAM user for the CLI.The following is the security policy:

AWSLambdaFullAccess

AmazonAPIGatewayAdministrator

AmazonCognitoPowerUser

When using the aws configure command to set up the CLI, you need to set the current AWS region as the default. Otherwise, you need to explicitly specify the region for each AWS CLI command using the --region option.

At the same time, it is also recommended that you enable the CLI autocompletion feature described in the documentation. To test whether the AWS CLI installation and configuration are correct, you can try executing the command：‘aws lambda list-functions’ to get a list of AWS Lambda functions that have been created under your account, along with the configuration information for each function, such as memory size, timeout, execution role, etc.

The default output format of the CLI is JSON, but it can be changed during the initial configuration of the CLI using the --output option. To invoke the function we just created, use the following syntax in the command line, and the JSON event is in single quotes. If you are using the AWS CLI on Windows to invoke the Lambda function, you need to change the single quotes mentioned above to double quotes and repeat once.

For example, --payload'' should be changed to --payload"{""name"":""Peter""}".

The output of the function is written to a local file. For example, if you want to greet "Peter," enter the following command in the command line. If you did not specify the region where you created and run AWS Lambda when configuring the AWS CLI, you must specify it at the end of the command using the --region parameter; otherwise, the above command will result in an error.

Execute the following command in the command line to test the output of function when no name is provided as input; the returned message will be "Hi, world!"