Getting Started

Installation

pip install capo-s3

Usage

from capo_s3 import AsyncS3Client


async def main():
    async with AsyncS3Client() as s3:
        # Example: call the abort_multipart_upload operation
        response = await s3.abort_multipart_upload()
        print(response["request_charged"])

Pagination

Some operations in this SDK support pagination. If the operation supports pagination it will have an iter_ prefixed method that returns an async iterator.

from capo_s3 import AsyncS3Client


async def main():
    async with AsyncS3Client() as s3:
        # Example: paginate over list_buckets
        async for item in s3.iter_list_buckets():
            print(item)

Streaming Request

Some operations accept a streaming request body. Pass an async iterator of bytes chunks, or the whole body as bytes, for the streaming parameter.

A plain iterator can be sent only once, so if a request fails after its body was transmitted the operation is not retried. To get retries for streamed uploads, pass a Body instead: it wraps a source that can be reopened, and every attempt streams a fresh copy. Body.from_path (sync client) and Body.async_from_path (async client, needs anyio) stream a file from disk; Body(opener) takes any context manager that yields a (stream, length) pair.

from capo_s3 import AsyncS3Client, Body


async def main():
    async with AsyncS3Client() as s3:
        # Example: call put_object with a streaming request body
        async def chunks():
            yield b'Hello, World!'

        # content_length is required: AWS must know the total body size up front
        response = await s3.put_object(body=chunks(), content_length=13)
        print(response)

        # Or pass the whole body as bytes
        response = await s3.put_object(body=b'Hello, World!')
        print(response)

        # Or stream a file with Body: the file is reopened on every retry
        # and Content-Length is taken from its size, so no content_length needed
        response = await s3.put_object(body=Body.async_from_path("hello.txt"))
        print(response)

Streaming Response

Some operations return a streaming response body. Use the operation as an async context manager and iterate over the response field to read chunks.

from capo_s3 import AsyncS3Client


async def main():
    async with AsyncS3Client() as s3:
        # Example: call get_object and read the streaming response
        async with s3.get_object() as response:
            async for chunk in response["body"]:
                print(chunk)

Waiters

Waiters poll an operation until a resource reaches a desired state. If the operation supports waiters it will have a wait_until_ prefixed method.

from capo_s3 import AsyncS3Client


async def main():
    async with AsyncS3Client() as s3:
        # Example: wait for bucket_exists
        await s3.wait_until_bucket_exists(max_wait_time=300)

Presigning

Some operations support presigning, which generates a URL that can be used without credentials. Use the presigned_ prefixed method on the client to get a presigned URL.

from capo_s3 import AsyncS3Client


async def main():
    async with AsyncS3Client() as s3:
        # Example: get a presigned URL for delete_object
        url = s3.presigned_delete_object()
        print(url)

Error Handling

The SDK raises exceptions for errors returned by the API. Catch them to handle failures gracefully.

from capo_s3 import AsyncS3Client
from capo_s3.error import NoSuchUpload


async def main():
    async with AsyncS3Client() as s3:
        try:
            await s3.abort_multipart_upload()
        except NoSuchUpload as e:
            print(f"Error: {e}")
            print(e.data)  # additional error data

Retrying

The SDK retries failed operations automatically. Retry behaviour follows the Smithy specification: errors are retried based on their is_retryable and is_throttling_error attributes. Throttling errors use a longer base delay. Network-level failures (connection errors and timeouts) are also retried. Non-retryable errors, such as client errors without the @retryable trait, are raised immediately without further attempts.

The number of attempts defaults to 3 and can be changed at the client level via retry_max_attempts, or per call via config_overrides.

from capo_s3 import AsyncS3Client


async def main():
    async with AsyncS3Client() as s3:
        # Default: 3 attempts for every operation
        response = await s3.abort_multipart_upload()

        # Override per operation
        response = await s3.abort_multipart_upload(config_overrides={"retry_max_attempts": 5})

        # Disable retries for this call
        response = await s3.abort_multipart_upload(config_overrides={"retry_max_attempts": 1})