### Jira - [X] My PR addresses the following [Airflow Jira](https://issues.apache.org/jira/browse/AIRFLOW/) issues and references them in the PR title. For example, "\[AIRFLOW-XXX\] My Airflow PR" - https://issues.apache.org/jira/browse/AIRFLOW-2920
### Description This adds https://github.com/kubernetes/kubernetes/blob/release-1.0/docs/user-guide/downward-api.md metadata to pods spun up by the Kubernetes executor. This allows one to then dynamically specify a namespace in the DAG task definition with: ``` task1 = KubernetesPodOperator( namespace=os.getenv('POD_NAMESPACE'), ... ``` Thus allowing multiple Kubernetes deployments to use the same Docker image. ### Tests - [x] My PR adds the following unit tests __OR__ does not need testing for this extremely good reason: There does not appear to be tests for the manifest the Kubernetes executor generates. ### Commits - [X] 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](http://chris.beams.io/posts/git-commit/)": ### Documentation - [ ] In case of new functionality, my PR adds documentation that describes how to use it. ### Code Quality - [x] Passes `git diff upstream/master -u -- "*.py" | flake8 --diff` @dimberman [ Full content available at: https://github.com/apache/incubator-airflow/pull/3774 ] This message was relayed via gitbox.apache.org for [email protected]
