LambdaからAPI Gateway(IAM認可)へのアクセス方法 [Python版]

import os
import urllib.request
from botocore.credentials import Credentials
from botocore.awsrequest import AWSRequest
from botocore.auth import SigV4Auth

def lambda_handler(event):
    ENDPOINT = "https://XXXXXXXXXX.execute-api.ap-northeast-1.amazonaws.com/STAGE"
    PATH = "/YOUR/RESOURCE"

    awsreq = AWSRequest(method="GET", url=ENDPOINT+PATH)

    # Sign
    credentials = Credentials(
        os.environ["AWS_ACCESS_KEY_ID"],
        os.environ["AWS_SECRET_ACCESS_KEY"],
        os.environ["AWS_SESSION_TOKEN"])
    SigV4Auth(credentials, "execute-api", os.environ["AWS_REGION"]).add_auth(awsreq)

    # Request
    req = urllib.request.Request(awsreq.url, method=awsreq.method,
                                 headers=awsreq.headers)
    with urllib.request.urlopen(req) as res:
        body = res.read()

    # Do something 

X-Amz-Date: 20190701T020706Z
X-Amz-Security-Token: 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
Authorization: AWS4-HMAC-SHA256 Credential=ASIAVHFXXXXXXXXXXXXX/20190701/ap-northeast-1/execute-api/aws4_request, SignedHeaders=host;x-amz-date;x-amz-security-token, Signature=ac00aaab0b00fe0a000000e0fd0a00c00aab00000b0000a0a000bddb0b000d