Handlers

AWS Lambda Handler

Copy page

The AWS Lambda handler is used to send requests to AWS Lambda. This handler can be used as an alternative to AWS API Gateway when exposing Lambda functions as an API or HTTP endpoint.

IAM Permissions

Zuplo requires access to execute your Lambda function. Create an IAM user and grant that account only the permission needed to invoke the Lambda function. The IAM user does not require console access, only API access. The IAM user requires the AWSLambdaRole role. This role can be scoped to only the specific Lambda functions required.

Setup via Portal

To set up the AWS Lambda handler in the portal UI, select the AWS Lambda handler on any route.

Configure the properties for your AWS Lambda function.

Setup via routes.oas.json

Set up the AWS Lambda handler by editing the routes.oas.json file directly. Configure the handler property on any route's x-zuplo-route property.

Code
{
  "handler": {
    "export": "awsLambdaHandler",
    "module": "$import(@zuplo/runtime)",
    "options": {
      "accessKeyId": "$env(AWS_ACCESS_KEY_ID)",
      "functionName": "demo-post-1",
      "region": "us-east-2",
      "secretAccessKey": "$env(AWS_SECURE_ACCESS_KEY)"
    }
  }
}

Options

The AWS Lambda handler accepts the following options:

• accessKeyId (required): The AWS access key ID for authentication. Use an environment variable reference like $env(AWS_ACCESS_KEY_ID).
• secretAccessKey (required): The AWS secret access key. Use an environment variable reference like $env(AWS_SECURE_ACCESS_KEY).
• functionName (required): The name of the AWS Lambda function to invoke.
• region (required): The AWS region where the Lambda function runs (e.g., us-east-2).
• binaryMediaTypes (optional): An array of content types to convert to base64-encoded strings when sending to the Lambda function.
• returnAmazonTraceIdHeader (optional): When true, includes the X-Amzn-Trace-Id header in the response. Default: false.
• useLambdaProxyIntegration (optional): When true, sends the request using the AWS API Gateway event format. Default: false.
• payloadFormatVersion (optional): The API Gateway payload format version. Set to "1.0" or "2.0". Only applies when useLambdaProxyIntegration is true.
• useAwsResourcePathStyle (optional): When true, converts Zuplo-style path parameters (:param) to AWS-style ({param}) in resourcePath. Default: false.

Binary Media Types

For content types, the binaryMediaTypes option allows specifying which content types get converted to base64 encoded strings when sent as the body to the AWS Lambda function. See AWS docs for details.

Code
{
  "handler": {
    "export": "awsLambdaHandler",
    "module": "$import(@zuplo/runtime)",
    "options": {
      "accessKeyId": "$env(AWS_ACCESS_KEY_ID)",
      "functionName": "demo-post-1",
      "region": "us-east-2",
      "secretAccessKey": "$env(AWS_SECURE_ACCESS_KEY)",
      "binaryMediaTypes": ["image/png", "application/pdf"]
    }
  }
}

X-Amzn-Trace-Id Header

For the purposes of troubleshooting and tracing, it can be useful to return the X-Amzn-Trace-Id header in the response. This can help correlate AWS Lambda events or errors with Zuplo requests/responses. This header is disabled by default, but it can be enabled by setting the configuration option returnAmazonTraceIdHeader to true.

Code
{
  "handler": {
    "export": "awsLambdaHandler",
    "module": "$import(@zuplo/runtime)",
    "options": {
      "accessKeyId": "$env(AWS_ACCESS_KEY_ID)",
      "functionName": "demo-post-1",
      "region": "us-east-2",
      "secretAccessKey": "$env(AWS_SECURE_ACCESS_KEY)",
      "returnAmazonTraceIdHeader": true
    }
  }
}

Compressed Body Content

The Zuplo handler supports gzip and deflate compression of the content of the AWS Lambda response body property. In order to instruct the Zuplo handler to decompress the body content add a property on the outgoing event called bodyEncoding and set the value to gzip or deflate.

The response event would look like this:

Code
{
  "isBase64Encoded": true,
  "bodyEncoding": "gzip",
  "body": "COMPRESSSED AND BASE64 ENCODED BODY",
  "...": "other properties..."
}

API Gateway Compatibility

The AWS Lambda handler can also call Lambda functions that were built for API Gateway.

Setting options.useLambdaProxyIntegration to true will tell the handler to call the function with the event format that matches with AWS API Gateway. You can also choose between the payload format by setting options.payloadFormatVersion to either 1.0 or 2.0.

The value for requestContext.resourcePath sent to the AWS Lambda function is the parameterized path of the route. Zuplo uses path-to-regex style paths (for example /my/route/:param1) instead of OpenAPI style paths, for example, /my/route/{param1} for routes. By default, the value of resourcePath is the Zuplo route value. Setting useAwsResourcePathStyle to true will convert the value to the AWS format.

For more details about the AWS payload formats see AWS's documentation.

Below is an example lambda handler configured for proxy integration with payload format 2.0.

Code
{
  "handler": {
    "export": "awsLambdaHandler",
    "module": "$import(@zuplo/runtime)",
    "options": {
      "accessKeyId": "$env(AWS_ACCESS_KEY_ID)",
      "functionName": "demo-post-1",
      "region": "us-east-2",
      "secretAccessKey": "$env(AWS_SECURE_ACCESS_KEY)",
      "useLambdaProxyIntegration": true,
      "payloadFormatVersion": "2.0",
      "useAwsResourcePathStyle": true
    }
  }
}