Facing issues while ingesting logs to promtail

Hello,

I’m experimenting promtail behind LB as per this link How we're making it easier to use the Loki logging system with AWS Lambda and other short-lived services | Grafana Labs
Basically, I’m trying to ingest logs to Loki like this cloudwatch >> Kinesis >> Promtail >> Loki

I deployed promtail behind Load Balancer, but when I try to ingest data from AWS kinesis I’m getting this error.
“The response received from the endpoint is invalid. See Troubleshooting HTTP Endpoints in the Firehose documentation for more information. Reason:. Response for request c5a2ce85-4ebc-4108-bc01-99a14bc690d6 must contain a ‘content-type: application/json’ header. Raw response received: 404: 404 page not found”,
I used HTTP endpoint option in kinesis to ingest data, I’m not sure whether it’s possible or not.
Could anyone please help me here.

As per AWS, I found that Kinesis Data Firehose to successfully deliver data to custom HTTP endpoints, these endpoints must accept requests and send responses using certain Kinesis Data Firehose request and response formats. So it’s expecting application/json response format. Does promtail giving any such response?
https://docs.aws.amazon.com/firehose/latest/dev/httpdeliveryrequestresponse.html#responseformat