[
https://issues.apache.org/jira/browse/AIRFLOW-2839?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16566253#comment-16566253
]
ASF GitHub Bot commented on AIRFLOW-2839:
-----------------------------------------
XD-DENG opened a new pull request #3678: [AIRFLOW-2839] Refine Doc
Concepts->Connections
URL: https://github.com/apache/incubator-airflow/pull/3678
### Jira
- [ ] 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-2839
- In case you are fixing a typo in the documentation you can prepend your
commit with \[AIRFLOW-XXX\], code changes always need a Jira issue.
### Description
- [x] Here are some details about my PR, including screenshots of any UI
changes:
We can define connections either in metadata database or environment
variables.
However, how about there are connections with the same conn_id in both
metadata database and environment variables? Will one of them be picked? Which
one? Or a random one will be picked?
The answer is: Airflow will check environment variables
first.https://github.com/apache/incubator-airflow/blob/master/airflow/hooks/base_hook.py#L70
The "random picking" mechanism will only be applicable for multiple
connections with the same conn_id in metadata database (if there is no
connection with the same conn_id defined in environment variables).
This should be made clear in the documentation.
### Tests
- [ ] My PR adds the following unit tests __OR__ does not need testing for
this extremely good reason:
### 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/)":
1. Subject is separated from body by a blank line
1. Subject is limited to 50 characters (not including Jira issue reference)
1. Subject does not end with a period
1. Subject uses the imperative mood ("add", not "adding")
1. Body wraps at 72 characters
1. 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
- [x] Passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
----------------------------------------------------------------
This is an automated message from the Apache Git Service.
To respond to the message, please log on GitHub and use the
URL above to go to the specific comment.
For queries about this service, please contact Infrastructure at:
[email protected]
> Answer a question in doc: what if I have connections with the same conn_id in
> both metadata and environment variables?
> ----------------------------------------------------------------------------------------------------------------------
>
> Key: AIRFLOW-2839
> URL: https://issues.apache.org/jira/browse/AIRFLOW-2839
> Project: Apache Airflow
> Issue Type: Improvement
> Components: configuration, Documentation
> Reporter: Xiaodong DENG
> Assignee: Xiaodong DENG
> Priority: Critical
>
> We can define connections either in metadata database or environment
> variables.
>
> However, how about there are connections with the same conn_id in both
> metadata database and environment variables? Will one of them be picked?
> Which one? Or a random one will be picked?
>
> The answer is: Airflow will check environment variables
> first.[https://github.com/apache/incubator-airflow/blob/master/airflow/hooks/base_hook.py#L70]
> The "random picking" mechanism will only be applicable for multiple
> connections with the same conn_id in metadata database (if there is no
> connection with the same conn_id defined in environment variables).
>
> This should be made clear in the documentation.
--
This message was sent by Atlassian JIRA
(v7.6.3#76005)
