consul/website/content/docs/lambda/index.mdx

---
layout: docs
page_title: AWS Lambda
description: >-
  Consul supports registering AWS Lambda functions as Consul services. This
  section documents the process of integrating AWS Lambda with Consul services.
---

# AWS Lambda Overview

You can configure Consul to allow services in your mesh to invoke Lambda functions, as well as allow Lambda functions to invoke services in your mesh. Lambda functions are programs or scripts that run in AWS Lambda. Refer to the AWS [Lambda website](https://aws.amazon.com/lambda/) for additional information.

## Register Lambda functions into Consul 

The first step is to register your Lambda functions into Consul. We recommend using the [Lambda registrator module](https://github.com/hashicorp/terraform-aws-consul-lambda/tree/main/modules/lambda-registrator) to automatically synchronize Lambda functions into Consul. You can also manually register Lambda functions into Consul if you are unable to use the Lambda registrator.

Refer to [Register Lambda Functions Overview](TODO) for additional information about registering Lambda functions into Consul.

## Invoke Lambda functions from Consul service mesh

After registering AWS Lambda functions, you can invoke Lambda functions from the Consul service mesh through terminating gateways (recommended) or directly from connect proxies.

Refer to Invoke Lambda Functions from Services for details.

## Invoke mesh service from Lambda function 

You can also add the `consul-lambda-extension` plugin as a layer in your Lambda functions, which enables them to send requests to services in the mesh. The plugin starts a sidecar proxy that directs requests from Lambda functions to [mesh gateways](docs/connect/gateways#mesh-gateways). The gateways route traffic to the destination service to complete the request.  

![Invoke mesh service from Lambda function](/img/invoke-service-from-lambda-flow.svg)

Refer to [Invoke Services from Lambda Functions](TODO) for additional information about registering Lambda functions into Consul.

## Cross-datacenter communication

You can use the following Consul features to send cross-datacenter requests between Lambda functions and mesh services. 

### Mesh gateway WAN federation

Mesh gateways enable you to route traffic to services within and across Consul datacenters. WAN federation refers to designating a _primary datacenter_ that contains authoritative information about all datacenters, including service mesh configurations and access control list (ACL) resources. Refer to [Mesh Gateways for WAN Federation](/docs/connect/gateways/mesh-gateway/wan-federation-via-mesh-gateways) for additional information.

Note that mesh gateways do not implement L7 traffic management by default. As a result, requests from Lambda functions ignore service routes and splitters.

#### Admin partitions 

If admin partitions are enabled and the datacenters are federated across the WAN using mesh gateways, then you can only route requests from Lambda functions by applying an [`exported-services`](/docs/connect/config-entries/exported-services) configuration entry to export their service instances. This is required even if the upstream for the Lambda function is in the same admin partition. Otherwise, Consul does not populate the mesh gateways with the routing information.

You can also use the [admin partitions](/docs/enterprise/partitions) feature included with Consul Enterprise to define separate administrative areas within a datacenter. If admin partitions are not enabled and the datacenters are federated across the WAN using mesh gateways, then you can route all services through the mesh gateways by default. You do not need to use the [`exported-services`](/docs/connect/config-entries/exported-services) configuration entry to export service instances.