[jira] [Commented] (AIRFLOW-3069) Decode output of S3 file transform operator

["ASF GitHub Bot (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/AIRFLOW-3069?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16619625#comment-16619625 ] 

ASF GitHub Bot commented on AIRFLOW-3069:
-----------------------------------------

sbilinski opened a new pull request #3914: [AIRFLOW-3069] Log all output of the S3 file transform script
URL: https://github.com/apache/incubator-airflow/pull/3914
 
 
   ### Jira
   
   - [x] My PR addresses the following [Airflow Jira](https://issues.apache.org/jira/browse/AIRFLOW/) issues and references them in the PR title.
     - [https://jira.apache.org/jira/browse/AIRFLOW-3069](https://jira.apache.org/jira/browse/AIRFLOW-3069)
   
   ### Description
   
   - [x] Here are some details about my PR, including screenshots of any UI changes:
   
   The output of the process spawned by `S3FileTransformOperator` is not properly decoded, which makes reading logs rather difficult. Additionally, the `stderr` stream is only shown when process exit code is not equal to `0`.
   
   I would like to propose the following changes to `S3FileTransformOperator`:
   
   - Send both output streams (stdout & stderr) to the logger, regardless of the outcome (if any data is present)
   - Decode the output, so that new lines can be displayed correctly.
   - Include process exit code in the exception message, if the process fails.
   
   ### Tests
   
   - [x] My PR adds the following unit tests __OR__ does not need testing for this extremely good reason:
   
   I've added a separate case for testing `transform_script` with output present. Since logging is essential in this case, the test checks if a valid message was passed to the logging module. 
   
   ### 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
   
   - [x] 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`
   

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> Decode output of S3 file transform operator
> -------------------------------------------
>
>                 Key: AIRFLOW-3069
>                 URL: https://issues.apache.org/jira/browse/AIRFLOW-3069
>             Project: Apache Airflow
>          Issue Type: Improvement
>          Components: aws
>    Affects Versions: 1.10.0
>            Reporter: Szymon Bilinski
>            Assignee: Szymon Bilinski
>            Priority: Trivial
>
> h3. Current behaviour
> {{S3FileTransformOperator}} logs {{stdout}} of the underlying process as such:
> {code}
> [2018-09-15 23:17:13,850] {{s3_file_transform_operator.py:122}} INFO - Transform script stdout b'Copying /tmp/tmpd5rjo8g0 to /tmp/tmpd3vkhzte\nDone\n'
> {code}
> While {{stderr}} is omitted entirely, unless exit code is not {{0}} (in this case it's included in the exception message only).
> h3. Proposed behaviour
> 1. Both streams are logged, regardless of the underlying process outcome (i.e. success or failure).
> 2. Stream output is decoded before logging (e.g. {{\n}} is replaced with an actual new line). 
> 3. If {{transform_script}} fails, the exception message contains return code of the process.



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