Use temporary file in GCSToS3Operator

[rafalh]

Use temporary file in GCSToS3Operator instead of keeping copied file content in the process memory. It allows copying big files on machines with small RAM size.

[boring-cyborg]

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[github-actions]

The PR is likely OK to be merged with just subset of tests for default Python and Database versions without running the full matrix of tests, because it does not modify the core of Airflow. If the committers decide that the full tests matrix is needed, they will add the label 'full tests needed'. Then you should rebase to the latest main or amend the last commit of the PR, and push it with --force-with-lease.

[potiuk]

Cool!

[potiuk]

Some tests are failing (related) though

[raphaelauv]

maybe add an option to the operator, so user have the choice

in_memory:bool = True

[potiuk]

maybe add an option to the operator, so user have the choice

in_memory:bool = True

Is there any drawback to not having it ? I believe this is higly unlikely to have less disk than memory?

[rafalh]

I was considering to add in_memory argument but I agree it does not bring much and unnecessary increases operator implantation and API complexity. AFAIK other operators also use temporary files and don't have an option to change it.
I through test failures were unrelated to my changes but I was wrong. I am going to look into them this week.

[raphaelauv]

If It's the commun pattern to write to a temp file , then you are right it's better to align the operators.

But for this operator since it could be about transferring big files , streaming from GCS to S3 with a multiparty upload would be great.

[potiuk]

But for this operator since it could be about transferring big files , streaming from GCS to S3 with a multiparty upload would be great.

Very much so, but it wasn't doing it - it was reading whole file to memory and pusing it.

[potiuk]

Any PRs for that are most welcome :)

[rafalh]

But for this operator since it could be about transferring big files , streaming from GCS to S3 with a multiparty upload would be great.

It would be cool but it would require more changes because AFAIK hook classes do not support streaming right now.

[boring-cyborg]

Awesome work, congrats on your first merged pull request!