[AIRFLOW-4472] Use json.dumps/loads for templating lineage data

[bolkedebruin]

Make sure you have checked all steps below.

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• My PR addresses the following Airflow Jira issues and references them in the PR title. For example, "[AIRFLOW-XXX] My Airflow PR"
  • https://issues.apache.org/jira/browse/AIRFLOW-4472
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Description

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jinja2 cannot use dict/lists as templates hence converting
it to json solves this while keeping complexity down.

Tests

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Is covered.

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Documentation

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Code Quality

• Passes flake8

[bolkedebruin]

cc: @feng-tao

This is a pre-requisite for the Papermill operator.

[ssYkse]

Hi!
This work, however for some reason is not part of the airflow 1.10.10 release (and earlier).
As it is merged into master, I assume it was lost somewhere in other merges.

[sankroh]

Can you guys release this please?

[Minutis]

Would like to see this one released too.

[potiuk]

I believe it was never meant to be released @kaxil @ashb @bolkedebruin? I am not 100% sure as it has no tests, but I think this one gets rather deeply into the operator/context behaviour and it might have some undesireable effects (on the other hand maybe it's better to cherry-pick it now because otherwise people might hit similar problems when migrating to 2.0)?

[bolkedebruin]

It's meant to be updated significantly. It's about 70% there and I need some time to finish it.