[AIRFLOW-5252] Move GCP Transfer to core

[turbaszek]

This commit moves GCP Transfer from contrib to core.
For more information check AIP-21.

Jira

• My PR addresses the following Airflow Jira issues and references them in the PR title.
  • https://issues.apache.org/jira/browse/AIRFLOW-5252

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  This commit moves GCP Transfer from contrib to core. For more information check AIP-21.

Tests

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Code Quality

• Passes flake8

[hagope]

Hi @nuclearpinguin, I'm thinking of coding some operators for Gsheets. For example,
GoogleCloudStorageToGsheetsTransferOperator
GsheetsToGoogleCloudStorageTransferOperator
S3ToGsheetsTransferOperator
GsheetsToS3TransferOperator

Few questions, 1.) is it a good idea? 2.) should we do it in cloud_storage_transfer_service.py or should there be a new gsheets.py files that implements operators for gsheets... also share any ideas for gsheet operators you think may be useful.

[mik-laj]

Hi.

We should use Gcs instead GoogleCloudStorage. My have prepared change plans for all GCP to have unified name. The plan has been approved by Google. In the near future we will introduce changes.

It should be new file gcs_to_gsheets.py.

cloud_storage_transfer_service.py contains integration to Google service that allow create transfer job, so it not transfer operator. It's operator that perform action in external service.
https://cloud.google.com/products/data-transfer/

Have you read the GCP Integration guide? this is an amazing source of knowledge about operator names.

[mik-laj]

I think, you will be interested in this operator also:
#5822