Using aws lambda with queue

Question

Pulumi · Accepted Answer

To create an AWS Lambda function that is triggered by an AWS Simple Queue Service (SQS) queue, you will need to perform the following steps using Pulumi:

1. **Create a Lambda Function**: Define a Lambda function resource in Pulumi that includes your code and any required dependencies.
2. **Create an SQS Queue**: Define an SQS Queue resource that your Lambda function will read messages from.
3. **Set Permissions**: Modify the Lambda function's permissions to allow it to be triggered by the SQS queue.
4. **Configure the Trigger**: Link your Lambda function to the SQS queue by adding the queue as an event source.

For the purposes of our example, we'll assume you've already created a Lambda function code package. If you haven't, you'd typically use a zip file containing your code and any dependencies.

Here's a Pulumi program in TypeScript that accomplishes these steps:

```typescript
import * as aws from "@pulumi/aws";

// Create an AWS Lambda function.
const lambdaFunction = new aws.lambda.Function("my-lambda-function", {
    code: new pulumi.asset.FileArchive("./function.zip"), // Path to your zipped code
    handler: "index.handler",                            // The function entrypoint in your code
    role: lambdaRole.arn,                                // IAM role with required permissions for the Lambda function
    runtime: aws.lambda.NodeJS12dXRuntime,              // Runtime for the function
});

// Create an SQS Queue.
const queue = new aws.sqs.Queue("my-queue", {
    visibilityTimeoutSeconds: 180 // Visibility timeout, adjust according to your needs.
});

// Allow the Lambda function to be triggered by the SQS queue.
const lambdaPermission = new aws.lambda.Permission("my-lambda-permission", {
    action: "lambda:InvokeFunction",
    function: lambdaFunction.name,
    principal: "sqs.amazonaws.com",
    sourceArn: queue.arn,
});

// Configure the Lambda function to be triggered by the SQS queue.
const lambdaEventSourceMapping = new aws.lambda.EventSourceMapping("my-lambda-event-source-mapping", {
    eventSourceArn: queue.arn,
    functionName: lambdaFunction.name,
});

// Export the name of the queue and the Lambda function URL
export const lambdaFunctionName = lambdaFunction.name;
export const queueName = queue.name;
```

Let's break down this program:

- We use `@pulumi/aws` to import the AWS module, which contains classes and functions to interact with AWS resources.
- We define the Lambda function with `aws.lambda.Function` and provide the path to the zipped code file with `FileArchive`.
- We define the SQS queue with `aws.sqs.Queue`. The `visibilityTimeoutSeconds` is the amount of time that a single message has to be processed before it's available again in the queue.
- We create a new permission for the Lambda function with `aws.lambda.Permission` that allows our SQS queue to invoke the Lambda function.
- We link the Lambda function to the queue with `aws.lambda.EventSourceMapping`. This automatically triggers the function with messages in the queue.

After deploying this code using Pulumi, the AWS resources will be provisioned in your AWS account and the Lambda function will begin processing messages from the SQS queue.

Remember, the IAM role for the Lambda function (`lambdaRole`) would need the appropriate permissions to run Lambda functions and permissions to be invoked by the SQS service. You can define this role using `aws.iam.Role` and `aws.iam.RolePolicyAttachment` in Pulumi as well if required.

To deploy the Pulumi program, install Pulumi and configure your AWS credentials, then run `pulumi up` within the directory of your Pulumi program. This command initiates the deployment of the resources as defined in your code.