We’ve got an Android app using the Genesys Cloud Web Messaging SDK that needs to trigger a specific backend process. The flow is: customer sends a command in the web chat, Architect catches it, and a Data Action calls an AWS Lambda function to handle the business logic.
The Lambda is deployed in us-east-1 and has a URL configured with InvokeMode: BUFFERED. The IAM role attached to the Lambda has the lambda:InvokeFunctionUrl permission, and I’ve verified the trust policy allows architect.genesys.cloud to call it.
Here’s the JSON config for the Data Action in Architect:
{
"request": {
"url": "https://lambda-url-id.lambda-url.us-east-1.on.aws/",
"method": "POST",
"headers": {
"Content-Type": "application/json"
},
"body": "{{ $.input }}"
},
"response": {
"statusCode": "{{ $.response.statusCode }}"
}
}
When I test this in Architect, it hangs for about 30 seconds then returns a 502 Bad Gateway. The response body is empty.
I checked the CloudWatch logs for the Lambda. The function is never triggered. It’s not even showing up in the metrics. This suggests the request isn’t reaching AWS at all, or it’s being dropped before invocation.
I tried adding the x-amz-invocation-type: ResponseStream header just to see if it changed anything, but same result. I also tried switching to INVOKE mode on the Lambda URL, which gave me a 403 Forbidden immediately. That makes me think the IAM permissions are partially working but something about the buffer mode or the URL signature is off.
Has anyone gotten buffered Lambda URLs to work with Architect Data Actions? Is there a specific header or payload structure required that isn’t in the docs? I’m stuck on why it’s returning 502 instead of a clearer auth error.
Buffered mode is async, so the HTTP client gets a 202 but Architect expects a 200 with a body, causing the 502. Switch to RESPONSE mode for InvokeUrl if you need the payload back immediately.
Are you sure the Lambda URL endpoint allows public access? Architect Data Actions can’t handle IAM auth headers directly. You might want to wrap the Lambda in an API Gateway instead. Here’s a quick Architect Data Action config that works reliably with AWS:
{
"method": "POST",
"url": "https://your-apigateway-id.execute-api.us-east-1.amazonaws.com/prod/trigger",
"headers": {
"Content-Type": "application/json"
},
"body": "{{conversation.id}}"
}
This avoids the 502 entirely.
Are you checking the raw HTTP response headers in the Architect Data Action debug output?
The 502 usually means the connection was established but the response parsing failed or timed out. Since you’re using BUFFERED mode, the Lambda returns a 202 Accepted with an empty body. Architect’s HTTP client sometimes throws a 502 if it expects content and gets nothing, or if the timeout is too short for the async handoff.
The point above is correct about switching to RESPONSE mode if you need data back. But if you just need to fire and forget, keep BUFFERED and ensure your Architect Data Action has a generous timeout. Also, check if your Lambda URL has a CORS configuration. Even for POST requests, missing CORS headers can cause weird gateway errors depending on how the client handles the preflight or response.
Here is the IAM policy snippet for the Lambda URL that usually fixes the auth handshake if you’re hitting public access issues:
{
"Version": "2012-10-17",
"Statement": [
{
"Effect": "Allow",
"Principal": "*",
"Action": "lambda:InvokeFunctionUrl",
"Resource": "arn:aws:lambda:us-east-1:123456789012:function:YourFunctionName",
"Condition": {
"StringEquals": {
"aws:SourceVpc": "vpc-12345678"
}
}
}
]
}
Wait, that Condition block is for VPC only. If your Architect instance is public (which it usually is), you might need aws:SourceIp or just remove the Condition if you’ve enabled public access on the Lambda URL. Just make sure InvokeMode matches what Architect expects.