AWS Lambda connection strings

April 11, 2024

Introduction

In this guide, you'll learn how to properly store and use PlanetScale MySQL connection strings for use in AWS Lambda Functions. We'll use a pre-built NodeJS app for this example, but you can follow along using your own application as well.

Prerequisites

• An AWS account
• A PlanetScale account

Set up the database

Let's start by creating the database. In the PlanetScale dashboard, click the "New database" button followed by "Create new database". Name the database lambda-connection-strings, or any other name that you prefer. Click "Create database".

Once your database has finished initializing, you'll need to enable the web console on production branches. To do this, go to the "Settings" tab, check "Allow web console access to production branches", and click "Save database settings".

Now, access the console of the main branch by clicking "Console", then "Connect".

Create a simple table & insert some data using the following script:

CREATE TABLE Tasks(
	Id int PRIMARY KEY AUTO_INCREMENT,
	Name varchar(100),
	IsDone bit
);

INSERT INTO Tasks (Name) VALUES ('Clean the kitchen');
INSERT INTO Tasks (Name) VALUES ('Fold the laundry');
INSERT INTO Tasks (Name) VALUES ('Watch the sportsball game');

You may run SELECT * FROM Tasks to ensure the data was properly added from the console.

Now we need to enable safe migrations on the main branch. Click the Dashboard tab, then click the cog icon in the upper right of the infrastructure card.

Toggle on the "Enable safe migrations" option and click the "Enable safe migrations" button.

Before moving on from the PlanetScale dashboard, grab the connection details to be used in the next step. Click on the Connect button to go to the Connect page. Enter a name for your password, and click the Create password button to generate a new password.

In the Select your language or framework section, select Node.js and note the details in the .env section of the guide. These details will be required to connect to the database.

Configure the Lambda function

Secrets in AWS Lambda functions, which include database connection strings, are often stored as environment variables with the Lambda function. We’ll be uploading a sample NodeJS app that has been provided and storing the connection string from the previous section as an environment variable to test.

Start by cloning the following Git repository:

git clone https://github.com/planetscale/aws-connection-strings-example.git

Log into the AWS Console, use the universal search to search for ‘Lambda’, and select it from the list of services.

Create a new function using the Create function button in the upper right of the console.

Name your function lambda-connection-strings (or any other name that suits you) and select NodeJS under Runtime. The other fields can be left as default. Click Create function to finish the initial setup of your Lambda.

On the next view, about halfway down the page you’ll see a section called Code source. Click the Upload from button, then .zip file.

Click the Upload button which will display a file browser. Select the aws-connection-strings-example.zip file from the dist folder of the provided repository. Click Save once it’s been selected.

The contents of the code editor under Code source should have updated to show the code stored in the zip file.

Configure environment variables

Next, you need to set the PlanetScale DATABASE_URL environment variable that you copied earlier. Select the Configuration tab, and click Edit.

You’ll be presented with a view to add or update environment variables. Click Add environment variable and the view will update with a row to add an environment variable. Set the Key field to DATABASE_URL and the Value to the connection string taken from the previous section. Click Save once finished.

Finally, test the function by selecting the Test tab, and then clicking the Test button.

An Execution results box will display above the Test event section. If the box is green, it likely means everything executed as expected. Click the dropdown next to Details to see the results of the query. Since the results of the query were logged out to the console, they will be displayed in the Log output section.

Need help?

Get help from the PlanetScale Support team, or join our GitHub discussion board to see how others are using PlanetScale.