Connect from AWS Lambda

AWS Lambda is a serverless, event-driven compute service that allows you to run code without provisioning or managing servers. It is a convenient and cost-effective solution for running various types of workloads, including those that require a database.

This guide describes how to set up a Neon database and connect to it from an AWS Lambda function using Node.js as the runtime environment. It covers:

• Creating a Lambda function using the Serverless Framework, which is a serverless application lifecycle management framework.
• Connecting your Lambda function to a Neon database.
• Deploying the Lambda function to AWS.

Prerequisites

• A Neon account. If you do not have one, see Sign up for instructions.
• An AWS account. You can create a free AWS account at AWS Free Tier. An IAM User and Access Key are required to programmatically interact with your AWS account. You must provide these credentials when deploying the Serverless Framework project.
• A Service Framework account. You can sign up at Serverless Framework.

Create a Neon project

If you do not have one already, create a Neon project:

1. Navigate to the Projects page in the Neon Console.
2. Click New Project.
3. Specify your project settings and click Create Project.

Create a table in Neon

To create a table, navigate to the SQL Editor in the Neon Console:

In the SQL Editor, run the following queries to create a users table and insert some data:

Create a Lambda function

Create the Lambda function using the Serverless Framework:

1. Install the Serverless Framework by running the following command:

2. Create a my-lambda project directory and navigate to it.

3. Run the serverless command to create a serverless project.

   Follow the prompts, as demonstrated below. You will be required to provide your AWS account credentials. The process creates an aws-node-project directory.

4. Navigate to the aws-node-project directory created by the previous step and install the node-postgres package, which you will use to connect to the database.

   After installing the node-postgres package, the following dependency should be defined in your package.json file:

5. In the aws-node-project directory, add a users.js file, and add the following code to it:

   The code in the users.js file exports the getAllUsers function, which retrieves all rows from the users table and returns them as a JSON object in the HTTP response body.

   This function uses the pg library to connect to the Neon database. It creates a new Client instance and passes the database connection string, which is defined in the DATABASE_URL environment variable. It then calls connect() to establish a connection to the database. Finally, it uses the query() method to execute a SELECT statement that retrieves all rows from the users table.

   The query method returns a Promise that resolves to an object containing the rows retrieved by the SELECT statement, which the function parses to retrieve the rows property. Finally, the function returns an HTTP response with a status code of 200 and a body that contains a JSON object with a single data property, which is set to the value of the rows variable.

6. Add the DATABASE_URL environment variable and the function definition to the serverless.yml file, which is located in your aws-node-project directory.

   note

   Environment variables can also be added to a .env file and loaded automatically with the help of the dotenv package. For more information, see Resolution of environment variables.

   You can copy the connection string from Connection Details widget the Neon Console. Add the DATABASE_URL under environment, and add sslmode=require to the end of the connection string to enable SSL. The sslmode=require option tells Postgres to use SSL encryption and verify the server's certificate.

7. Deploy the serverless function using the following command:

   The serverless deploy command generates an API endpoint using API Gateway. The output of the command appears similar to the following:

8. Test the generated endpoint by running a cURL command. For example:

   The response returns the following data:

Enabling CORS

If you make API calls to the Lambda function from your app, you will likely need to configure Cross-Origin Resource Sharing (CORS). Visit the AWS documentation for information about how to enable CORS in API Gateway.

You can run the following command to enable CORS to your local development environment:

You can find your api-id on the API Gateway dashboard:

Conclusion

In this guide, you have learned how to set up a Postgres database using Neon and connect to it from an AWS Lambda function using Node.js as the runtime environment. You have also learned how to use Serverless Framework to create and deploy the Lambda function, and how to use the pg library to perform a basic database read operations.