Setting up AWS Lambda Functions with IAM Auth for Data Actions

How-To-Articles
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Setting up AWS Lambda Functions with IAM Auth for Data Actions

Executive Summary & Architectural Context

When Genesys Cloud needs to interact with internal corporate databases or legacy on-premise systems, opening those databases directly to the public internet is a massive security violation. The modern architectural pattern is to use Serverless Middleware-specifically, an AWS Lambda function placed behind an Amazon API Gateway. The Lambda function securely queries your internal database and returns the result to Genesys Cloud.

However, leaving the API Gateway endpoint publicly open (even with an obscure URL) is unacceptable. Traditional API Keys can be easily leaked. The enterprise-grade solution is to secure the API Gateway using AWS IAM Authentication (Signature Version 4).

Genesys Cloud natively supports AWS IAM authentication for Data Actions. This masterclass details how to configure the cross-account IAM Trust Policies, deploy the AWS Integration inside Genesys Cloud, and securely invoke your Lambda functions without ever passing a static API key.

Prerequisites, Roles & Licensing

  • Licensing: Available on all Genesys Cloud CX tiers.
  • Roles & Permissions:
    • Genesys Cloud: Integrations > Integration > Edit, Integrations > Action > Edit
    • AWS: IAMFullAccess (to create Roles and Policies), APIGatewayAdministrator
  • Platform Dependencies:
    • An existing AWS Lambda function exposed via an API Gateway.

The Implementation Deep-Dive

1. The Architectural Handshake

Genesys Cloud does not use a static “password” to talk to AWS. Instead, it uses STS AssumeRole.

  1. You give Genesys Cloud an AWS Account ID and an IAM Role ARN.
  2. Genesys Cloud (acting from its own AWS infrastructure) attempts to assume your AWS Role.
  3. Your AWS account checks its Trust Policy. If it recognizes the Genesys Cloud core account ID as a trusted entity, it grants a temporary, short-lived STS token.
  4. Genesys Cloud uses that token to sign the HTTP request to your API Gateway (SigV4).

2. Creating the IAM Policy in AWS

First, define exactly what Genesys Cloud is allowed to do in your AWS account. It should only be allowed to invoke the specific API Gateway.

  1. Log into the AWS Management Console and navigate to IAM > Policies > Create policy.
  2. Select the JSON tab and paste the following, replacing the ARN with your actual API Gateway execution ARN:
{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Effect": "Allow",
            "Action": "execute-api:Invoke",
            "Resource": "arn:aws:execute-api:us-east-1:123456789012:abcdef123/*/GET/my-lambda-endpoint"
        }
    ]
}
  1. Name the policy GenesysCloud_APIGateway_Invoke.

3. Creating the IAM Role and Trust Relationship

Now, create the Role that Genesys Cloud will assume.

  1. In AWS IAM, navigate to Roles > Create role.
  2. For Trusted Entity Type, select Custom trust policy.
  3. You must enter the specific AWS Account ID used by Genesys Cloud for your region. (Note: This Account ID varies by region. For us-east-1, the Core account is usually 765628981432).
  4. Paste the Trust Policy:
{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Principal": {
        "AWS": "arn:aws:iam::765628981432:root"
      },
      "Action": "sts:AssumeRole",
      "Condition": {
        "StringEquals": {
          "sts:ExternalId": "YOUR_GENESYS_ORG_ID"
        }
      }
    }
  ]
}

[!IMPORTANT]
The sts:ExternalId is a critical security mechanism preventing the “Confused Deputy” problem. You MUST replace YOUR_GENESYS_ORG_ID with your actual Genesys Cloud Organization ID (found in Admin > Account Settings).

  1. Attach the GenesysCloud_APIGateway_Invoke policy you created in Step 2.
  2. Note the Role ARN (e.g., arn:aws:iam::123456789012:role/GenesysCloud_Lambda_Role).

4. Configuring the Integration in Genesys Cloud

With the AWS side locked down, configure the integration inside Genesys.

  1. Navigate to Admin > Integrations > Integrations.
  2. Install the AWS Lambda Data Actions (or Amazon API Gateway Data Actions) integration.
  3. In the Configuration tab, go to Credentials.
  4. Click Configure.
  5. Provide the Role ARN you copied from Step 3.
  6. Click Save and Activate. If the Trust Policy is correct, the integration will activate immediately.

5. Building the Data Action

  1. Create a new Custom Action under the AWS integration.
  2. Under Setup > Configuration > Request, configure the endpoint:
{
  "requestUrlTemplate": "https://abcdef123.execute-api.us-east-1.amazonaws.com/prod/my-lambda-endpoint",
  "requestType": "GET",
  "headers": {},
  "requestTemplate": "${input.rawRequest}"
}
  1. Notice there are NO authorization headers here. The Genesys Cloud infrastructure automatically intercepts the request, generates the SigV4 signature using the assumed role, injects the Authorization: AWS4-HMAC-SHA256... headers, and fires the payload.

Validation, Edge Cases & Troubleshooting

Edge Case 1: 403 Forbidden Errors

If the Data Action fails with a 403 Forbidden, the issue is almost always AWS-side permissioning.

  • Troubleshooting: Check your API Gateway. Ensure that Method Execution has Authorization set to AWS_IAM. If it is set to None, API Gateway will reject the SigV4 signed request because it wasn’t expecting authorization.
  • IAM Policy Check: Verify that the execute-api:Invoke resource ARN matches the exact deployed stage and HTTP method of your gateway.

Edge Case 2: Regional Account ID Mismatch

If the integration fails to activate in Genesys Cloud (throwing an STS AssumeRole error), you likely used the wrong Genesys Cloud AWS Account ID in your Trust Policy.

  • Troubleshooting: Genesys Cloud operates out of multiple AWS regions (us-east-1, eu-west-1, ap-southeast-2). Each region uses a different core AWS Account ID for STS AssumeRole. You must consult the official Genesys Cloud documentation to find the exact Account ID for your specific AWS region.

Official References