[AIRFLOW-2428] Add AutoScalingRole key to emr_hook

[dmnpignaud]

Jira

• My PR addresses the following Airflow Jira

Description

• Enable the use of the autoscaling functionality when creating an EMR cluster

Tests

• None

Commits

• My commits all reference Jira issues in their subject lines, and I have squashed multiple commits if they address the same issue. In addition, my commits follow the guidelines from "How to write a good git commit message":
  1. Subject is separated from body by a blank line
  2. Subject is limited to 50 characters (not including Jira issue reference)
  3. Subject does not end with a period
  4. Subject uses the imperative mood ("add", not "adding")
  5. Body wraps at 72 characters
  6. Body explains "what" and "why", not "how"

Documentation

• In case of new functionality, my PR adds documentation that describes how to use it.
  • When adding new operators/hooks/sensors, the autoclass documentation generation needs to be added.

Code Quality

• Passes git diff upstream/master -u -- "*.py" | flake8 --diff

[ashb]

Hmmm, I wonder if it might be an idea to do self.get_conn().run_job_flow(**config) - that we don't have to stay up-to-date with the AWS API.

For that to work we'd need three config.setdefault() calls for the three list-types. I also don't know if all the kwargs are optional or not (but I suspect they are).

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.