Upgrade AtoM to ElasticSearch to 8.x

[anvit]

Upgrade AtoM to use ES v8.19. This would be a step towards moving AtoM to a current version of ElasticSearch.

[zsanmartin]

On the technical requirements in the official documentation, this is said:

Elasticsearch 7.x (we use ES 7.10 in development). ES 7.11 - 8.15 is not supported by AtoM as it uses Server Side Public License (SSPL) and Elastic License 2.0 (ELv2), which are not approved by the Open Source Initiative.

According to https://www.elastic.co/pricing/faq/licensing, however, since 2024, Elastic Search has added OSI-approved AGPLv3 to its licensing.

I understand that this means the licensing is no longer an obstacle for upgrading, is that correct?

[anvit]

@zsanmartin yes, ES 8.16+ is available under AGPLv3, so licensing isn't a problem anymore.

Elastic stopped publishing an OSS version of the docker images and OSS binaries past ES 7.10.2 however, and the more recent versions of the image they publish are not under the OSS license. This is currently one of the things we're trying to find a solution for, since we'd like to be able to update our docker compose file to point to an OSS version that developers are able to use