Luigi

This release come with a few new features and some changed behaviors. Hopefully bringing us a tiny step towards scheduling heaven.

luigi:
- Luigi can now send error emails in easy-to-digest batches. https://github.com/spotify/luigi/pull/1916 Thanks daveFNBuck
- New behavior for `task.clone()` https://github.com/spotify/luigi/pull/1630 Thanks ChrisBeaumont
- Various bigquery improvements from Spotify engineers: https://github.com/spotify/luigi/pull/1888 https://github.com/spotify/luigi/pull/1917
- Add `target.temporary_path()` as a new recommended ways to deal with temporary paths in luigi https://github.com/spotify/luigi/pull/1909 [(docs)](http://luigi.readthedocs.io/en/stable/api/luigi.target.html#luigi.target.FileSystemTarget.temporary_path)

luigi.scheduler:
- Reverted the behavior introduced in [2.3.0](https://github.com/spotify/luigi/releases/tag/2.3.0). https://github.com/spotify/luigi/pull/1926

There have been a lot of other features, cleanups and bugfixes! See all commits
[here](https://github.com/spotify/luigi/compare/2.3.3...2.4.0).

Biggest risk of breakage for people updating early:
- File locking strategy just got changed (on Unix) https://github.com/spotify/luigi/pull/1886 Thanks nmandery

Other things:
- Range for Minutes. https://github.com/spotify/luigi/pull/1863 Thanks j-santander
- CORS headers for responses from scheduler. https://github.com/spotify/luigi/pull/1870 Thanks jessicaaustin
- Docs and configurationf for email updated. Finally! https://github.com/spotify/luigi/pull/1871 Thanks daveFNbuck
- Further fixes to Batch running functionality. https://github.com/spotify/luigi/pull/1858 Thanks daveFNbuck

And many more other small improvements. Thanks to everyone who've contributed!

This is mostly a bug-fix release.

---
- Changed behaviour (read bugfix) in local locking https://github.com/spotify/luigi/pull/1842
- Changed behaviour (read bugfix) in disabling workers https://github.com/spotify/luigi/pull/1839
- Many bugfixes to the scheduler, particularly related to the Batch running functionality.

[Here](https://github.com/spotify/luigi/compare/2.3.1...2.3.2) are the changes commit by commit.

This release mainly fixes bugs introduced in the two latest releases and also
some older bugs.

---
- Bugfix regarding sftp https://github.com/spotify/luigi/pull/1825
- Bugfix regarding error emails with smtp https://github.com/spotify/luigi/pull/1821
- Bugfix regarding spark tasks https://github.com/spotify/luigi/pull/1819
- Bugfixes regarding visualiser https://github.com/spotify/luigi/pull/1817 https://github.com/spotify/luigi/pull/1818

[Here](https://github.com/spotify/luigi/compare/2.3.0...2.3.1) are the changes commit by commit.

There's been over a month since the last release. This new release includes a
bunch of new features. What I like the most is that they all come with full and
proper documentation!

luigi:
- Fixed lockfile bugfix introduced in 2.2.0 https://github.com/spotify/luigi/pull/1809 Thanks nugend
- Retcodes improved https://github.com/spotify/luigi/pull/1771 Thanks fabriziodemaria
- Added [NumericalParameter](https://github.com/spotify/luigi/pull/1799)
and [ChoiceParameter](https://github.com/spotify/luigi/pull/1800) Thanks brcopeland
- Per-task configurable retry policies! https://github.com/spotify/luigi/pull/1791 Thanks javrasya
- Luigi can now batch tasks! https://github.com/spotify/luigi/pull/1784 Thanks daveFNbuck

luigi.scheduler:
- We now have a new definition of the UPSTREAM statuses. New intuition is that
`UPSTREAM_FAILED` means that that task cannot run because all downstream
tasks have failed or worse (like being disabled). As an effect there will be
much much fewer tasks considered to have an upstream status. https://github.com/spotify/luigi/pull/1789

There have been a lot of other features, cleanups and bugfixes! See all commits
[here](https://github.com/spotify/luigi/compare/2.2.0...2.3.0).

There's been 3 months since the latest release. Making Google's results on [readthedocs](http://luigi.readthedocs.io/) outdated and gives a stale feeling to luigi. Enjoy updated and hopefully bugfree software. :)

At least read these
- Luigi finally has user-land configurable task status messages https://github.com/spotify/luigi/pull/1625
- Parameters: From now on, you must not pass `None` as the default for a
parameter. Usually, passing the empty string `''` is a sufficient
replacement. If you don't do this luigi will print a deprecation warning.
https://github.com/spotify/luigi/pull/1624.
- Logging for server: Things are greatly improved
now as of https://github.com/spotify/luigi/pull/1633
and https://github.com/spotify/luigi/pull/1636.
Here's my jotted down usage info about it here
https://github.com/spotify/luigi/issues/1752#issuecomment-231266977.

Main changes

luigi:
- More fine grained eventhandlers https://github.com/spotify/luigi/pull/1698
- Range: Finally a proper way to pass along parameters: https://github.com/spotify/luigi/pull/1675
- From this release, we'll also bump the debian verion number. https://github.com/spotify/luigi/pull/1718
- Print your dependency tree as ascii art! https://github.com/spotify/luigi/pull/1680
- We now have a template for PR's! https://github.com/spotify/luigi/pull/1655

luigi.contrib:
- AWS: You can now set the session token: https://github.com/spotify/luigi/pull/1702/files
- Salesforce: Add support for multiple results https://github.com/spotify/luigi/pull/1686
- FTP: Configurable port https://github.com/spotify/luigi/pull/1689
- MSSQL support: https://github.com/spotify/luigi/pull/1650
- Streaming mapreduce: Allow additional archives https://github.com/spotify/luigi/pull/1649
- Streaming mapreduce: Recognize the Google File System formats https://github.com/spotify/luigi/pull/1664
- Streaming mapreduce: `mrrunner.py` is not hardcoded as the binary being run https://github.com/spotify/luigi/pull/1565

Various goodies
- Cleanup: https://github.com/spotify/luigi/pull/1734
- Cleanup: https://github.com/spotify/luigi/pull/1735
- Cleanup: https://github.com/spotify/luigi/pull/1723
- Cleanup: https://github.com/spotify/luigi/pull/1677
- Cleanup: https://github.com/spotify/luigi/pull/1640
- Cleanup: https://github.com/spotify/luigi/pull/1722
- Speedup: https://github.com/spotify/luigi/pull/1737
- Speedup: https://github.com/spotify/luigi/pull/1681
- Docs: https://github.com/spotify/luigi/pull/1729
- Docs: https://github.com/spotify/luigi/pull/1662
- Docs: https://github.com/spotify/luigi/pull/1716
- Bugfix: https://github.com/spotify/luigi/pull/1708
- Bugfix: https://github.com/spotify/luigi/pull/1643
- Improved error message: https://github.com/spotify/luigi/pull/1692

Contribution spirit

A few great examples that show how improvements are well-receieved no matter how small they are. Yet these "small" changes helps hundreads of people reading the docs of luigi. https://github.com/spotify/luigi/pull/1672 https://github.com/spotify/luigi/pull/1642

Other changes

There were [even more changes](https://github.com/spotify/luigi/compare/2.1.1...2.2.0) which we didn't include in these release notes. Like every contribution, whether merged or not we are happy for getting them. So please keep contributing! :)