Leverage aiohttp internal handling of `chunked` argument

[jakob-keller]

Description of Change

https://github.com/aio-libs/aiobotocore/pull/1077#pullrequestreview-1912935492

Assumptions

Replace this text with any assumptions made (if any)

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• [ ] I have ensured that the awscli/boto3 versions match the updated botocore version

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Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 85.94%. Comparing base (aec730a) to head (cdd466e).

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[thehesiod]

is this change covered by tests? AFK for a bit to check the coverage

[jakob-keller]

is this change covered by tests? AFK for a bit to check the coverage

I am not sure and we touched upon that here: https://github.com/aio-libs/aiobotocore/pull/1077#pullrequestreview-1912935492.

For our purposes, aiobotocore's chunked() duplicates logic already provided by aiohttp's update_transfer_encoding(): https://github.com/aio-libs/aiohttp/blob/7571eb9f65fde72fd6ccadcc5bfe2dc81f3a126c/aiohttp/client_reqrep.py#L439

I believe it is safe to drop chunked() when modern releases of aiohttp are used, i.e. any release we support in requirements.

[jakob-keller]

@Dreamsorcerer: Could you advise us on this PR, please? I believe that aiohttp will handle chunked requests correctly, without having to pass the chunked argument explicitely. Any guidance?

[Dreamsorcerer]

From reading the code, it looks like in the code, if the body has no size and no Content-Length header is set, then chunked will be set regardless of what you pass in: https://github.com/aio-libs/aiohttp/blob/3de518a0a324b082cca3ed94ef5a9338b4745759/aiohttp/client_reqrep.py#L503

Then it looks like it will handle chunked as per: https://github.com/aio-libs/aiohttp/blob/3de518a0a324b082cca3ed94ef5a9338b4745759/aiohttp/client_reqrep.py#L444-L457

From my reading of that, the code expects to set the Transfer-Encoding header itself. Which is probably why the code you're deleting removed the Transfer-Encoding header. So, I'd suggest spending a bit more time understanding why a Transfer-Encoding header would have been set in first place, seems to me that there should never be a Transfer-Encoding header passed in here.

[jakob-keller]

From my reading of that, the code expects to set the Transfer-Encoding header itself. Which is probably why the code you're deleting removed the Transfer-Encoding header. So, I'd suggest spending a bit more time understanding why a Transfer-Encoding header would have been set in first place, seems to me that there should never be a Transfer-Encoding header passed in here.

Thank you, that helped a lot!

Transfer-Encoding headers are set by botocore: https://github.com/boto/botocore/blob/149ae67cc8909ab03c11337392e676711a438d90/botocore/awsrequest.py#L405

We are removing them to satisfy expectations of aiohttp.

Everything works as it should.