Set elasticsearch version

[kvokka]

DESCRIPTION HERE

(check all that apply)

• [ ] tests added
• [x] tests passing
• [ ] README updated (if needed)
• [ ] README Table of Contents updated (if needed)
• [x] History.md and version in gemspec are untouched
• [x] backward compatible
• [x] feature works in elasticsearch_dynamic (not required but recommended)

With elasticsearch v 8.0.0 this gem is not working. The simplest option to make this version is to set elasticseatch gem version to tested release 7.x.x, which is the best practice anyway.

Close #944

[cosmo0920]

We don't want to use this strategy to fix breakages for elasticsearch 8.0 series.

[kvokka]

Thank you for such a quick answer

I appreciate, that you want to use the latest version.

But the bases in the gem CI are falsely green, at least for MacOs with the master branch. Meaning that the gem does not have es 8.0 support yet (the CI on this gem was executed before elasticsearch gem release). But with the version of elasticsearch 7.17 then it is usable.

It's not straightforward to move from 7.17 to 8.0, see #948 in which I made only obvious changes, but it is requiring a lot of polishing and specs fixes. We are unfortunately NOT there yet. I'll be very happy if these changes are released quickly, cos ofc this approach is better.

Until then the only option to use this gem is if the developer sets elasticsearch gem version manually to 7.17 (or earlier).

It would be great to use this without any hacks, but we are where we are. And this is the gem that is included in the default package of fluentd. And at least for me, it means that it should work from the box.