README.md

Terraform Modules for CloudFront Authentication

This directory contains the Terraform configuration for adding authentication to a CloudFront distribution. Currently only OKTA Native authentication is supported.

Usage

The Terraform modules for each identity provider are in the modules directory. Refer to the examples directory for Terraform configuration that you can include in your project and adapt. Refer to the variables.tf file of the module to see all the available input variables. Below is an example for OKTA Native.

1. Call the module in your Terraform configuration. CloudFront uses the us-east-1 region, so you must pass a us-east-1 provider to the module.

   module "auth" {
     source = "github.com/iress/cloudfront-auth//infra/terraform/modules/okta_native"
   
     # Lambda function version to deploy (see the Releases page of this GitHub repository)
     release_version = "v4.0.0"
   
     name        = "my-website-auth"
     org_url     = "https://my-org.okta.com/oauth2/default"
     client_id   = "Nf2qSD9wXKU9ph8an22T"
     domain_name = "my-cloudfront-site.example.com"
   
     # aws.global_services is a us-east-1 provider
     providers = {
       aws = aws.global_services
     }
   }

2. Add a lambda_function_association to your aws_cloudfront_distribution resource:

   resource "aws_cloudfront_distribution" "distribution" {
     # ... other configuration ...
   
     # lambda_function_association is also supported by ordered_cache_behavior
     default_cache_behavior {
       # ... other configuration ...
   
       lambda_function_association {
         event_type = "viewer-request"
         lambda_arn = module.auth.auth_lambda_arn
       }
     }
   }

Requirements

This module requires wget to be installed on the machine or container that runs Terraform.

Logs

Logs are written to CloudWatch. The table below shows where the logs can be found, where {name} is the value of the name input variable in the Terraform module.

Function	Log group name	Region
Authentication	/aws/lambda/us-east-1.{name}	The region closest to the user who made the request to the website
Secret rotation	/aws/lambda/{name}-rotation	us-east-1

Destroying

The first time you run terraform destroy you may receive the following error:

Lambda was unable to delete arn:aws:lambda:us-east-1:553479592532:function:my-website-auth:1 because it is a replicated function. Please see our documentation for Deleting Lambda@Edge Functions and Replicas.

When this occurs, wait (up to a few hours) for CloudFront to delete the Lambda function replicas, then run terraform destroy again.