---
layout: docs
page_title: Manual Lambda Function Registration
description: >-
  Register AWS Lambda functions with Consul service mesh using the Consul Lambda registrator. The Consul Lambda registrator automates Lambda function registration.
---

# Manual Lambda Function Registration

This topic describes how to manually register Lambda functions into Consul. Refer to [Automate Lambda Function Registration](/consul/docs/lambda/registration/automate) for information about using the Lambda registrator to automate registration.

## Requirements

Verify that your environment meets the requirements specified in [Lambda Function Registration Requirements](/consul/docs/lambda/registration).

To manually register Lambda functions so that mesh services can invoke them, you must create and apply a service registration configuration for the Lambda function and write a [service defaults configuration entry](/consul/docs/connect/config-entries/service-defaults) for the function.

## Register a Lambda function

You can manually register Lambda functions if you are unable to automate the process using the Lambda registrator.

1. Create a configuration for registering the service. You can copy the following example and replace `<SERVICE_NAME>` with your Consul service name for the Lambda function:

   <CodeBlockConfig filename="lambda.json">

   ```json
   {
     "Node": "lambdas",
     "SkipNodeUpdate": true,
     "NodeMeta": {
       "external-node": "true",
       "external-probe": "true"
     },
     "Service": {
       "Service": "<SERVICE_NAME>"
     }
   }
   ```

    </CodeBlockConfig>

1. Save the configuration to `lambda.json`.

1. Send the configuration to the `catalog/register` API endpoint to register the service, for example:
   ```shell-session
   $ curl --request PUT --data @lambda.json localhost:8500/v1/catalog/register
   ```

1. Create the `service-defaults` configuration entry and include the AWS tags used to invoke the Lambda function in the `EnvoyExtensions` configuration. Refer to [Supported `EnvoyExtension` arguments](#supported-envoyextension-arguments) for more information. 

The following example creates a `service-defaults` configuration entry named `lambda`:

   <CodeBlockConfig filename="lambda-service-defaults.hcl">

   ```hcl
   Kind = "service-defaults"
   Name = "<SERVICE_NAME>"
   Protocol  = "http"
   EnvoyExtensions = [
     {
       "Name": "builtin/aws/lambda",
       "Arguments": {
         "Region": "us-east-2",
         "ARN": "<INSERT ARN HERE>",
         "PayloadPassthrough": true
       }
     }
   ]
   ```

   </CodeBlockConfig>

1. Issue the `consul config write` command to store the configuration entry. For example:
   ```shell-session
   $ consul config write lambda-service-defaults.hcl
   ```

### Supported `EnvoyExtension` arguments

The `lambda` Envoy extension supports the following arguments:

- `ARN` (`string`) - Specifies the [AWS ARN](https://docs.aws.amazon.com/general/latest/gr/aws-arns-and-namespaces.html) for the service's Lambda. `ARN` must be set to a valid Lambda function ARN.
- `Region` (`string`) - Specifies the AWS region the Lambda is running in. `Region` must be set to a valid AWS region where the Lambda function exists.
- `PayloadPassthrough` (`boolean: false`) - Determines if the body Envoy receives is converted to JSON or directly passed to Lambda.
- `InvocationMode` (`string: synchronous`) - Determines if Consul configures the Lambda to be invoked using the `synchronous` or `asynchronous` [invocation mode](https://docs.aws.amazon.com/lambda/latest/operatorguide/invocation-modes.html).
