Elasticsearch: Provide a list of all settings

[salyh]

Provide a comprehensive complete list of all settings for each es version like https://gist.github.com/jprante/7dccffa7f0c0c7576fa9 does for 1.2

[jpountz]

This would certainly be useful. One issue is that the way we manage settings makes it hard to have a centralized place with the list of all settings so this would require some refactoring...

[clintongormley]

Related to #6732

[clintongormley]

Also, I think that each setting should have an explanation next to it. And we need to add a test to throw an exception if a new setting is not documented.

[j0hnsmith]

Django has a good example https://docs.djangoproject.com/en/1.8/ref/settings/

[clintongormley]

With #6732 on the verge of being finished (including the ability to return default settings), we're finally in a place where we can do this.

[dakrone]

This is available with the ?include_defaultls option, but since that doesn't include documentation for the settings, it might be good to add it to the documentation.

[geekpete]

Some other things that'd be great to include in such docs might be:

• min/max values or a list of possible values if not numerical
• units that the values are in
• if the setting applies to cluster/node/index level
• if the setting/config can be disabled and how (eg -1 or whatever)
• if the setting is dependent on other settings (some of the x-pack ssl settings are the only examples I can think of in this case, not related to the open source project though. (Unsure how many dependent settings there are in Elasticsearch currently, unsure if it seems like something that a project might try to avoid if possible?)

[jasontedor]

We do not think we should do this. See discussion in #26251 and #33741. Closing.