Trying to invoke a Lambda from an Architect Data Action. Getting a 403 Access Denied error. The Lambda logs show the role is assumed, but permissions seem off. Here’s the trust policy I’m using. Is the principal correct for Genesys?
{
“Effect”: “Allow”,
“Principal”: {
“Service”: “architect.genesys.cloud”
},
“Action”: “sts:AssumeRole”
}
The execution role has lambda:InvokeFunction attached. What am I missing?
Are you using a pure CloudFormation stack or the Genesys Cloud AWS integration? The principal needs to be the specific AWS account ID from the integration, not a generic service name. Check your AWS console under IAM roles to see the exact external ID.
When troubleshooting this configuration, it’s important to note that that service principal format won’t work for cross-account calls. I’ve seen this exact pattern cause permission mismatches in the extension logs, much like how a misconfigured browser policy can block background sync. To get this resolved, just configure a dedicated role with an aws:PrincipalOrgID condition instead, and you’ll stop the 403 errors when Architect rotates credentials. I usually recommend checking the Chrome DevTools Network tab first to verify the auth handshake, but in this case, you’ll want to check the VPC endpoint routing next.
Could you clarify which Chrome version and extension build you’re currently testing against? Also, are you seeing any CORS warnings or storage quota limits in the console that might be interfering with the credential rotation flow? Let me know if you need help parsing the logs or adjusting the compatibility settings for the rotated tokens.
Problem
The Trust Policy you posted will not function for Genesys Cloud integrations. The Service Principal format is invalid in this context. We encountered this exact block during the WEM adherence export lambda deployment. The Role Assumption requires the specific AWS Account ID linked to your tenant, along with the External ID. Without the External ID, the STS call fails immediately with a 403.
Code
{
"Version": "2012-10-17",
"Statement": [
{
"Effect": "Allow",
"Principal": {
"AWS": "arn:aws:iam::[GENESYS_ACCOUNT_ID]:root"
},
"Action": "sts:AssumeRole",
"Condition": {
"StringEquals": {
"sts:ExternalId": "[YOUR_EXTERNAL_ID_FROM_INTEGRATION]"
}
}
}
]
}
Error
You receive the 403 Access Denied because the Condition is not satisfied. The External ID functions as a token to prevent confused deputy attacks. If the ID in the Policy does not match the value in the Genesys AWS Integration Config, the invoke fails.
Question
Did you verify the AWS Account ID in the Integration Settings? The ID sometimes changes if you migrated from a legacy setup. Check the IAM Role ARN in the console. The ID often differs.
terraform-provider-aws handles the STS handshake pretty straightforwardly, but let’s walk through exactly why you’re seeing that 403. When the Genesys Cloud platform fires off that STS request, it’s actually attaching the external ID right along with it. If your trust policy doesn’t explicitly validate that string using a condition block, AWS will just flat-out reject the role assumption. That’s the exact reason the 403 pops up even though the role technically exists in your account. Also, just a heads-up: you can’t rely on a generic service name for cross-account calls here. You absolutely need to pull the specific AWS account ID straight from your Genesys Cloud integration settings, otherwise the handshake won’t authenticate properly.
genesyscloud_cxascode is where state drift usually bites us, so let’s break down how to handle it step by step. If that external ID gets rotated manually in the console but your Terraform state file isn’t refreshed to match, you’re going to run into drift issues. My usual workflow is to always grab the freshest value directly from the integration details page right before you run your apply, and I always keep a state drift backup handy just in case the refresh throws a wrench in things. Since the assume_role_policy attribute expects a raw JSON string, wrapping it in the jsonencode function is the best way to keep the formatting sane and avoid those pesky syntax errors.
assume_role_policy = jsonencode({
Version = "2012-10-17"
Statement = [{
Effect = "Allow"
Principal = { AWS = "arn:aws:iam::123456789012:root" }
Action = "sts:AssumeRole"
Condition = { StringEquals = { "sts:ExternalId" = var.genesys_external_id } }
}]
})
terraform-provider-aws also requires that the var.genesys_external_id variable has to be an exact match to what’s configured on the platform under Integrations > AWS. If there’s even a single character off, the STS call will fail immediately. On the permissions side, make sure your execution role actually has the lambda:InvokeFunction policy attached, since the CX-as-Code provider relies on that for the backend triggers. And finally, just double-check that external ID string for any sneaky typos or trailing spaces—it’s saved me from a few late-night debugging sessions!