Not able to access vpc based aws elasticsearch domain using proxy server

[a2hksy (Akshay Kumar)]

Hi,
I have created a cluster of AWS Elasticsearch service in a VPC. There are many services in my organization that are in different VPC and want to access my Elasticsearch domain.
To do that a public proxy server can be used and services can communicate with Elasticsearch by using this proxy server.
So I have created an Nginx server with the domain name "xyz.example.com" that will forward the request to the Elasticsearch.
And by using the IAM user, I will authorize the Elasticsearch.

I am using this code to connect with Elasticsearch -

from elasticsearch import Elasticsearch, RequestsHttpConnection
from requests_aws4auth import AWS4Auth

host = 'xyz.example.com'
region = 'ap-southeast-1' # e.g. us-west-1

service = 'es'

awsauth = AWS4Auth(value_of_access_key, value_of_secret_key, region, service)

es = Elasticsearch(
    hosts = [{'host': host, 'port': 443}],
    http_auth = awsauth,
    use_ssl = True,
    verify_certs = True,
    connection_class = RequestsHttpConnection
)

print(es.cluster.health)

So i am getting error -
TransportError(403, u'{"message":"The request signature we calculated does not match the signature you provided. Check your AWS Secret Access Key and signing method. Consult the service documentation for details."}')

but when I use native URL of the elastic domain and try to connect from the same vpc. Then I am not getting any error - 

from elasticsearch import Elasticsearch, RequestsHttpConnection
from requests_aws4auth import AWS4Auth

host = 'test-domain.us-east-1.es.amazonaws.com'
region = 'ap-southeast-1' # e.g. us-west-1

service = 'es'

awsauth = AWS4Auth(value_of_access_key, value_of_secret_key, region, service)

es = Elasticsearch(
    hosts = [{'host': host, 'port': 443}],
    http_auth = awsauth,
    use_ssl = True,
    verify_certs = True,
    connection_class = RequestsHttpConnection
)

print(es.cluster.health)

Getting the expected result.