Add elastic 8 support via github.com/elastic/go-elasticsearch/v8

[harryzcy]

Closes #30752

github.com/elastic/go-elasticsearch/v8 only support Elasticsearch v8, so the previous code is kept for v7 compatibility.

[silverwind]

Also update the action:

gitea/.github/workflows/pull-db-tests.yml

Line 95 in ad4e902

image: elasticsearch:7.5.0

gitea/.github/workflows/pull-db-tests.yml

Line 160 in ad4e902

image: elasticsearch:7.5.0

[harryzcy]

elasticsearch 7 is still supported until 9.x is released. I think we should support both

[silverwind]

Ok, it's actually fine to test the minimum supported version. We do this for databases too.

[stevapple]

IIRC github.com/elastic/go-elasticsearch/v8 doesn’t support (at least) older Elasticsearch v7 clusters, nor OpenSearch.

Additional work is required to maintain compatibility with these distros.

[harryzcy]

I'm adding a ELASTICSEARCH_VERSION setting. Not sure if it's the best option, and not sure if we can auto detect the major version of ElasticSearch used

[silverwind]

The REST API returns version at root as version.number:

https://opster.com/guides/elasticsearch/how-tos/check-elasticsearch-version/

[harryzcy]

Fixing up last few issues, probably Elastic REST API authentication related.
Somehow the Elastic related test with Postgres db test is not running. I'm testing on my own fork right now

[silverwind]

Regarding opensearch (and I'm fine leaving that out in this PR), I think the status quo is:

olivere/elastic/v7 should be compatible with elasticsearch 7 and opensearch 1
elastic/go-elasticsearch/v8 is only compatible with elasticsearch 8
opensearch-project/opensearch-go is compatible with opensearch 2 and maybe opensearch 1

So unfortunately, it seems to support them all I'm afraid we need 3 modules. It's a mess. API is supposed to be similar on all of them. Maybe it'd be also an option to consume the REST API plainly without those modules.

[harryzcy]

Hmm, is TestESIndexAndSearch in modules/indexer/code not triggered? there should be a few errors with that test

[silverwind]

Looks reasonable and I would like to try upgrading my instance to elasticsearch 8, so I would give it a go.