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A Guide to Provisioning Lambda Functions in VPC with Internet Access

Provisioning a Lambda Function in a VPC with Internet Access

Have you ever wanted to use Lambda to access resources in your VPC but struggled with internet access? Provisioning a Lambda Function in a VPC with internet access may sound daunting, but it’s essential for organizations that operate securely in the cloud.

In this article, we will walk you through how to create a VPC with public and private subnets and enable internet access for your Lambda Function while ensuring that your resources are kept secure.

Creating a VPC with Public and Private Subnet Groups

The first step in provisioning a Lambda Function in a VPC is creating a VPC with both public and private subnet groups. A VPC is a fully customizable virtual network that provides a secure and isolated environment for your resources.

Subnets are segments of a VPC that are created in specific availability zones within a region. Public subnets are connected to the internet and can receive traffic from outside the VPC, whereas private subnets provide an additional layer of security by isolating resources that don’t need to be publicly available.

Resources within private subnets can access the internet through a network address translation (NAT) gateway.

Enabling Internet Access for Lambda Function in VPC

Enabling internet access for your Lambda Function requires configuring permissions to manage elastic network interfaces and placing the function in a private subnet with a route table rule pointing to a NAT gateway. Lastly, allow outbound access in the function’s security group.

Permissions to Manage Elastic Network Interfaces

An Elastic Network Interface (ENI) is a virtual network interface that can be attached to an instance in a VPC. When creating the Lambda Function, ensure that you configured the necessary IAM policies to allow it to manage ENIs.

Placing Function in Private Subnet with Route Table Rule Pointing to NAT Gateway

To enable internet access for a Lambda Function, you need to place the function in a private subnet. A NAT gateway is required to forward traffic to and from the internet to resources in the private subnet.

A route table is created for each subnet that associates the subnet with a specific route table. To enable internet access to the private subnet, a route table rule should be created pointing to the NAT gateway.

Allowing Outbound Access in Function’s Security Group

The Security Group associated with your Lambda Function controls network traffic to and from the Lambda Function itself. You need to create an outbound rule to allow traffic to go outside of your VPC to the internet.

Code Implementation

Now that we have successfully created a VPC with public and private subnets and enabled internet access for our Lambda Function in our VPC let us look at creating a Lambda function and placing it in a VPC.

Creating a Lambda Function and Placing it in VPC

Create your Lambda Function normally but, this time, ensure that you select the VPC and Subnet where you will place your Lambda Function. Once this configuration is complete, you can use the default security group and the AWSLambdaVPCAccessExecutionRole managed policy.

Implementing Function to Request API and Return Response

After the Lambda Function’s setup is complete, you can now implement it to perform any intended functionality. For example, you may use the node-fetch package to request data from an API and return the response.

The node-fetch package is a lightweight and quick package that provides a consistent API for consuming HTTP-based APIs.

Conclusion

Provisioning a Lambda Function in a VPC with internet access requires setting up a VPC with public and private subnets, enabling internet access for your Lambda Function through the permissions to manage elastic network interfaces, placing the function in a private subnet with a route table rule pointing to a NAT gateway, and allowing outbound access in the functions security group. With these steps, you can have an already secure cloud environment that can securely run your Lambda Functions with internet access while still protecting your resources.

Deployment and Testing

After completing the implementation of VPC and Lambda Function and verifying that internet access is enabled for the Lambda Function via the private subnet and NAT gateway, it is time to deploy and test the Lambda function and verify that the function’s code can access resources within the VPC.

Deploying Lambda Function and VPC

Once the VPC and Lambda Function are created and configured, the next step is to deploy them. Deploying Lambda Functions is a straightforward process that can be done using the AWS Management Console, the AWS CLI, or any of the AWS SDKs.

To deploy a Lambda Function and its associated VPC, navigate to the Lambda Management Console.

Select the Lambda Function that you just created and click on the “Deploy” button. Choose the deployment package, specify the VPC configuration, the subnets, the security groups, and click on the “Deploy” button.

Testing Function’s Internet Access via Lambda Management Console

After successful deployment, the next step is to test the Lambda Function’s ability to connect to resources in the VPC and the internet. Since we configured the outbound rules on the function’s security group to allow traffic from the private subnet to the internet, we can use that private subnet to ping any publicly available internet resources like google.com.

To test that the Lambda Function has internet access via the private subnet, navigate back to the Lambda Management Console and choose the Lambda Function that you just created. Click on the “Test” button, and in the test event input, specify a JSON payload and configure your test settings.

Ensure that the Lambda function is executed in the private subnet, which contains the NAT gateway and has internet access. Once the execution is complete, you can check the CloudWatch logs to verify whether the Lambda function was successful in accessing the VPC.

Viewing CloudWatch Logs

AWS CloudWatch logs is a service that provides metrics, logs, and events for AWS resources and services. AWS Lambda integrates with CloudWatch Logs to store logs generated by your Lambda functions.

The logs are useful for debugging, auditing applications, and troubleshooting issues within your Lambda Function. To view the CloudWatch logs for your Lambda function, navigate to the AWS Management Console and click on the CloudWatch link.

Once you’re on the CloudWatch dashboard, navigate to the Logs section and select the Log Group that corresponds to your Lambda Function. Within the Log Group, you can access logs generated by the Lambda Function and view detailed information on specific invocations and executions.

Clean Up and Additional Resources

After testing and verifying that your Lambda function is working correctly, it’s time to clean up any provisioned resources that you no longer need. You can do this by navigating to the respective management console, selecting the resources you want to delete, and following the simple steps provided.

In case you want to continue learning or testing your knowledge, AWS provides numerous tutorials and additional resources. Some of the resources include additional AWS services like Amazon RDS, Amazon S3, AWS CloudFormation, AWS Elastic Beanstalk, to name a few.

AWS also offers online courses from AWS experts that cover multiple topics, including provisioning AWS resources, deploying applications on AWS, building scalable and secure applications in AWS, among others.

Conclusion

Provisioning a Lambda Function in a VPC with internet access is a vital step to ensure that you have an already secure cloud environment that can securely run your Lambda Functions with internet access while still protecting your resources. The process of creating a VPC with public and private subnets and enabling internet access for your Lambda function through a private subnet and NAT gateway can be a challenging task.

Still, with the above steps, you should have sufficient knowledge to deploy, test and clean up your Lambda functions and VPCs. AWS provides additional tutorials and online courses to enhance your knowledge, and the more knowledge you gain, the more you get to understand and appreciate AWS services and how they can be beneficial to your organization.

Provisioning a Lambda Function in a VPC with Internet Access is a crucial step in securing your resources and allowing Lambda functions to access resources in a private subnet while enabling internet access. Creating a VPC with public and private subnets, enabling internet access for Lambda Functions, deploying and testing the function, and deleting provisioned resources are the essential steps in provisioning a Lambda Function in a VPC with Internet Access.

AWS offers additional tutorials and courses for those wishing to learn more about AWS services and solidify their knowledge. The ability to provision a Lambda function in a VPC with internet access is critical for organizations operating securely in the cloud, and it is a skill worth mastering.

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