[AIRFLOW-5769] Move the S3_hook to /providers/aws/hooks

[mingrammer]

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Of course, this update will lead to the API breaking change. Therefore, all codes using S3_hook should change the import module names when this PR is merged.

So if you agree with this change, it would be better to include these updates in Airflow 2.0 rather than 1.x because it is kind of specification change.

[mik-laj]

Can you keep backwards compatibility and add missing tests?

[mingrammer]

Right now, I have no ideas for keeping backward compatibility with Python's case-sensitive nature.

[mik-laj]

Will this not work?
https://github.com/apache/airflow/blob/master/airflow/contrib/operators/bigquery_to_gcs.py

[mingrammer]

Ah! that is a good idea. I couldn't think about it. Thank you for help.

[mik-laj]

You should also add a note in the UPDATING.MD file

[mingrammer]

Ok. I'll do that. Thank you for guiding me 👍

[mingrammer]

@mik-laj I encountered a problem.

Some file systems (including macOS's default one) are case-insensitive, so we can't have both s3_hook.py and S3_hook.py simultaneously in those fs.

So we should use another filename to separate that both. How do you think about that move the s3_hook.py to contrib/hooks like other AWS hooks (i.e. aws_athena_hook, aws_lambda_hook etc) named as aws_s3_hook.py (and change the class name to class AWSS3Hook)?

And they (aws-*-hooks) look similar to each other.

class AWSAthenaHook(AwsHook):
    """
    Interact with AWS Athena to run, poll queries and return query results

    :param aws_conn_id: aws connection to use.
    :type aws_conn_id: str
    :param sleep_time: Time to wait between two consecutive call to check query status on athena
    :type sleep_time: int
    """

    INTERMEDIATE_STATES = ('QUEUED', 'RUNNING',)
    FAILURE_STATES = ('FAILED', 'CANCELLED',)
    SUCCESS_STATES = ('SUCCEEDED',)
...

class S3Hook(AwsHook):
    """
    Interact with AWS S3, using the boto3 library.
    """

    def get_conn(self):
        return self.get_client_type('s3')

[mik-laj]

We want to move this hook to a completely different package.
More information:
#6439
https://cwiki.apache.org/confluence/display/AIRFLOW/AIP-21%3A+Changes+in+import+paths
https://lists.apache.org/thread.html/d8c1a72113fc01088d77a4f6d33371e465d20f7aa0d16232d8f93559@%3Cdev.airflow.apache.org%3E

Please note that a change of class name should be done in a separate PR.

[mingrammer]

Well, I will follow the mentioned conventions. (/providers/hooks/~.py)

Yap. I’ll update this PR and send an additional PR for class name.

[mingrammer]

I'll update the UPDATING.md and other docs when #6446 is merged to avoid conflict and inconsistency.

(based on https://github.com/apache/airflow/pull/6446/files#diff-bb7ee25332d5fdca3ead2f545d72b359)

[mingrammer]

I updated the UPDATING.md and other reference file.

[codecov-io]

Codecov Report

Merging #6443 into master will decrease coverage by 0.17%.
The diff coverage is 95.83%.

@@            Coverage Diff            @@
##           master   #6443      +/-   ##
=========================================
- Coverage   83.88%   83.7%   -0.18%     
=========================================
  Files         631     632       +1     
  Lines       36638   36642       +4     
=========================================
- Hits        30732   30672      -60     
- Misses       5906    5970      +64

Impacted Files	Coverage Δ
airflow/hooks/S3_hook.py	100% <100%> (+4.25%)	⬆️
airflow/providers/aws/hooks/s3.py	95.74% <95.74%> (ø)
airflow/kubernetes/volume_mount.py	44.44% <0%> (-55.56%)	⬇️
airflow/kubernetes/volume.py	52.94% <0%> (-47.06%)	⬇️
airflow/kubernetes/pod_launcher.py	45.25% <0%> (-46.72%)	⬇️
airflow/kubernetes/kube_client.py	33.33% <0%> (-41.67%)	⬇️
...rflow/contrib/operators/kubernetes_pod_operator.py	70.14% <0%> (-28.36%)	⬇️
airflow/models/taskinstance.py	93.79% <0%> (+0.5%)	⬆️
airflow/jobs/scheduler_job.py	74.92% <0%> (+1.2%)	⬆️
... and 5 more

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[mingrammer]

And, Should I change the all import paths with new module path in the other files including test files? (in separate PR)

[mingrammer]

@mik-laj Please check it

[mik-laj]

And, Should I change the all import paths with new module path in the other files including test files? (in separate PR)

Oh. I didn't notice your question. Yes. Other references to this class should be improved.

[mingrammer]

Ok. I'll send a PR for that!