mirror of https://github.com/hashicorp/consul
82 lines
3.2 KiB
Markdown
82 lines
3.2 KiB
Markdown
---
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layout: docs
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page_title: Invoke Lambda Functions
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description: >-
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This topic describes how to invoke AWS Lambda functions from the Consul service mesh.
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---
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# Invoke Lambda Functions
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This topic describes how to invoke AWS Lambda functions from the Consul service mesh.
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## Overview
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You can invoke Lambda functions from the Consul service mesh through terminating gateways (recommended) or directly from connect proxies.
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### Terminating Gateway
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We recommend invoking Lambda functions through terminating gateways. This method supports cross-datacenter communication, transparent
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proxies, intentions, and all other Consul service mesh features.
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The terminating gateway must have [the appropriate IAM permissions](/docs/lambda/requirements#allow-envoy-to-invoke-the-lambda)
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to invoke the function.
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The following diagram shows the invocation procedure:
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<ImageConfig width={700}>
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</ImageConfig>
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1. Make an HTTP request to the local Connect proxy.
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1. The Connect proxy forwards the request to the terminating gateway.
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1. The terminating gateway invokes the function.
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### Connect Proxy
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You can invoke Lambda functions directly from a service's Connect proxy.
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This method has the following limitations:
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- Intentions are unsupported. Consul enforces intentions by validating the client certificates presented when a connection is received. Lambda does not support client certificate validation, which prevents Consul from supporting intentions using this method.
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- Transparent proxies are unsupported. This is because Lambda services are not
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registered to a proxy.
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This method is secure because AWS IAM permissions is required to invoke Lambda functions. Additionally, all communication is encrypted with Amazon TLS when invoking Lambda resources.
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The Envoy sidecar proxy must have the correct AWS IAM credentials to invoke the function. You can define the credentials in environment variables, EC2 metadata, or ECS task metadata.
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The following diagram shows the invocation procedure:
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<ImageConfig width={400}>
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</ImageConfig>
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1. Make an HTTP request to the local Connect proxy.
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2. The Connect proxy invokes the Lambda.
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## Invoke a Lambda Function
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Before you can invoke a Lambda function, register the service used to invoke
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the Lambda function and the service running in Lambda with
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Consul (refer to [registration](/docs/lambda/registration) for
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instructions). The service used to invoke the function must be deployed to the
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service mesh.
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1. Update the invoking service to use the Lambda service as an upstream. In the following example, the `destination_name` for the invoking service (`api`) points to a Lambda service called `authentication`:
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```hcl
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upstreams {
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local_bind_port = 2345
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destination_name = "authentication"
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}
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```
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1. Issue the `consul services register` command to store the configuration:
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```shell-sesion
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$ consul services register api-sidecar-proxy.hcl
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```
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1. Call the upstream service to invoke the Lambda function. In the following example, the `api` service invokes the `authentication` service at `localhost:2345`:
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```shell-session
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$ curl https://localhost:2345
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```
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