Example demonstrating how to inspect canonical HTTP requests to S3

example.py

import boto3


s3_client = boto3.client("s3")

# List available operations.
s3_client._service_model.operation_names

operation_name = "ListObjectsV2"
params = {
    "Bucket": "my-bucket",
    "Prefix": "path/to/somewhere",
    "MaxKeys": 100,
}

# From `s3_client._make_api_call`.
operation_model = s3_client._service_model.operation_model(operation_name)
request_context = {
    "client_region": s3_client.meta.region_name,
    "client_config": s3_client.meta.config,
    "has_streaming_input": operation_model.has_streaming_input,
    "auth_type": operation_model.auth_type,
}

request_dict = s3_client._convert_to_request_dict(
    params,
    operation_model,
    context=request_context
)

handler, event_response = s3_client.meta.events.emit_until_response(
    "before-call.{endpoint_prefix}.{operation_name}".format(
        endpoint_prefix=client._service_model.endpoint_prefix,
        operation_name=operation_name,
    ),
    model=operation_model, params=request_dict,
    request_signer=client._request_signer, context=request_context)

if event_response is None:
    http, parsed_response = s3_client._endpoint.make_request(
        operation_model, request_dict)
    # XML response.
    print(http.content)