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:

Navigate to the Projects page in the Neon Console.
Click New Project.
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 TABLE users (
    id SERIAL PRIMARY KEY,
    name TEXT NOT NULL,
    email TEXT NOT NULL,
    created_at TIMESTAMPTZ DEFAULT NOW()
);

INSERT INTO users (name, email)
VALUES
    ('Alice', 'alice@example.com'),
    ('Bob', 'bob@example.com'),
    ('Charlie', 'charlie@example.com'),
    ('Dave', 'dave@example.com'),
    ('Eve', 'eve@example.com');

Create a Lambda function

Create the Lambda function using the Serverless Framework:

Install the Serverless Framework by running the following command:
```
npm install -g serverless
```
Create a my-lambda project directory and navigate to it.
```
mkdir neon-lambda
cd neon-lambda
```

Run the serverless command to create a serverless project.

serverless

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

? What do you want to make? AWS - Node.js - Starter
? What do you want to call this project? aws-node-project

✔ Project successfully created in aws-node-project folder

? Do you want to login/register to Serverless Dashboard? Yes
Logging into the Serverless Dashboard via the browser
If your browser does not open automatically, please open this URL:
https://app.serverless.com?client=cli&transactionId=jP-Zz5A9xu67PPYqzIhOe

✔ You are now logged into the Serverless Dashboard

? What application do you want to add this to? [create a new app]
? What do you want to name this application? aws-node-project

✔ Your project is ready to be deployed to Serverless Dashboard (org: "myorg", app: "aws-node-project")

? No AWS credentials found, what credentials do you want to use? AWS Access Role
(most secure)

If your browser does not open automatically, please open this URL: https://app.serverless.com/myorg/settings/providers?source=cli&providerId=new&provider=aws

To learn more about providers, visit: http://slss.io/add-providers-dashboard
? 
[If you encountered an issue when setting up a provider, you may press Enter to
skip this step]

✔ AWS Access Role provider was successfully created

? Do you want to deploy now? Yes

Deploying aws-node-project to stage dev (us-east-1, "default" provider)

✔ Service deployed to stack aws-node-project-dev (71s)

dashboard: https://app.serverless.com/myorg/apps/my-aws-node-project/aws-node-project/dev/us-east-1

functions:
  hello: aws-node-project-dev-hello (225 kB)

What next?
Run these commands in the project directory:

serverless deploy    Deploy changes
serverless info      View deployed endpoints and resources
serverless invoke    Invoke deployed functions
serverless --help    Discover more commands

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.
```
npm install pg
```
After installing the node-postgres package, the following dependency should be defined in your package.json file:
```
{
 "dependencies": {
   "pg": "^8.8.0"
 }
}
```
In the aws-node-project directory, add a users.js file, and add the following code to it:
```
'use strict';

const { Client } = require('pg');

module.exports.getAllUsers = async () => {
 var client = new Client(process.env.DATABASE_URL);
 client.connect();
 var { rows } = await client.query('SELECT * from users');
 return {
   statusCode: 200,
   body: JSON.stringify({
     data: rows,
   }),
 };
};
```
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.
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.
```
provider:
 name: aws
 runtime: nodejs14.x
 environment:
   DATABASE_URL: postgres://[user]:[password]@[neon_hostname]/[dbname]?sslmode=require

functions:
 getAllUsers:
   handler: users.getAllUsers
   events:
     - httpApi:
         path: /users
         method: get
```

Deploy the serverless function using the following command:

serverless deploy

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

Deploying aws-node-project to stage dev (us-east-1, "default" provider)

✔ Service deployed to stack aws-node-project-dev (60s)

dashboard: https://app.serverless.com/myorg/apps/aws-node-project/aws-node-project/dev/us-east-1

endpoint: GET - https://ge3onb0klj.execute-api.us-east-1.amazonaws.com/users

functions:

  getAllUsers: aws-node-project-dev-getAllUsers (225 kB)

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

curl https://eg3onb0jkl.execute-api.us-east-1.amazonaws.com/users | jq

The response returns the following data:

{
  "data": [
    {
      "id": 1,
      "name": "Alice",
      "email": "alice@example.com",
      "created_at": "2023-01-10T17:46:29.353Z"
    },
    {
      "id": 2,
      "name": "Bob",
      "email": "bob@example.com",
      "created_at": "2023-01-10T17:46:29.353Z"
    },
    {
      "id": 3,
      "name": "Charlie",
      "email": "charlie@example.com",
      "created_at": "2023-01-10T17:46:29.353Z"
    },
    {
      "id": 4,
      "name": "Dave",
      "email": "dave@example.com",
      "created_at": "2023-01-10T17:46:29.353Z"
    },
    {
      "id": 5,
      "name": "Eve",
      "email": "eve@example.com",
      "created_at": "2023-01-10T17:46:29.353Z"
    }
  ]
}

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:

aws apigatewayv2 update-api --api-id <api-id> --cors-configuration AllowOrigins="http://localhost:3000"

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

Screenshot 2023-01-09 at 16 20 34

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.