Adds HiveToDynamoDB Transfer Sample DAG and Docs

[ferruzzi]

Does what it says on the tin; adds sample dag and docs for an existing transfer.

Part of a project to simplify and standardize AWS sample dags and docs in preparation for adding System Testing.

Related: #21523
Related: #21475
Related: #21828
Related: #21920
etc...

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[ferruzzi]

I've removed this from others as I go through them, but in this case I thought it was a nice touch to add a disclaimer that the DAG won't run without prior setup. I can remove it if we would rather keep it uniform.

[ferruzzi]

Gah. PyCharm flagged that as a warning but it passed the local CI (./scripts/ci/testing/ci_run_airflow_testing.sh) so I thought it should pass here. Is there another way to use the task decorator in this case or should I convert it to a PythonOperator?

[ferruzzi]

Looks like chain() doesn't like @task decorated methods. Posted to the Slack server to discuss fix: https://apache-airflow.slack.com/archives/CCPRP7943/p1648498867915099

Option1) Convert the @tasks to PythonOperators.
Option 2) Replace chain() with the bitwise notation.
Option 3) "Fix" chain so it accepts the @task notated methods.
Option 4) Something else I haven't considered.

[potiuk]

Option 2) Replace chain() with the bitwise notation.

Followed by

Option 3) "Fix" chain so it accepts the @task notated methods.

In separate PR :)

[ferruzzi]

Created an Issue for it. If someone else gets to it before me then even better: #22594

[ferruzzi]

Rebased and fixed the chain() notation to bitwise for 2.1 compatibility.

[josh-fell]

Should convert this to TaskFlow API as well.

[ferruzzi]

I couldn't figure out a way to do it with the trigger_rule. I had tried @task(trigger_rule='all_done') as seen in 36368e96d3543e5ae873f135808d50f29cbfbcb6 but that fails static checks.

See: https://apache-airflow.slack.com/archives/CCPRP7943/p1648228076933559

[josh-fell]

Wasn't that because using chain()with TaskFlow API was not compatible with Airflow 2.1? You should be able to pass a trigger_rule directly to the decorator like you're trying to do with Airflow 2.1+

[ferruzzi]

Alright, I'll revert that and see. Maybe I just misread the error message. I'm in a meeting, but should have it pushed within the hour

[ferruzzi]

That didn't age well. 😛 Rebased and pushed reversion.

[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.

[ferruzzi]

CI is green. That concludes this little adventure in misreading error messages. Thanks for the help Jarek and Josh.

[potiuk]

@ferruzzi - your adventure was very, vey little. Read THIS #22548 (comment)

[ferruzzi]

@potiuk It was an adventure, not an Oddesy 😛