[Feature] Elasticsearch: update to new Java API

[jloisel]

Elasticsearch Rest High Level Client is deprecated in favor of:
https://www.elastic.co/guide/en/elasticsearch/client/java-api-client/7.17/index.html

There is still the possibility to have both clients inside a single application:
https://www.elastic.co/guide/en/elasticsearch/client/java-api-client/7.17/migrate-hlrc.html

Still, would be better to migrate to the new client which is the standard for Elasticsearch 8.x.x as well.

[rdehuyss]

I'm aware of this but it's currently low prio as less than 1% of the installations uses Elastic.

[jloisel]

Thanks for the feedback. As a workaround, we did:

• Add older sdk to classpath:

    <dependency>
      <groupId>org.elasticsearch.client</groupId>
      <artifactId>elasticsearch-rest-high-level-client</artifactId>
      <version>${elasticsearch.version}</version>
    </dependency>

• Create a Spring configuration to load the RestHighLevelClient:

@Configuration
@ConditionalOnProperty(prefix = "org.jobrunr.job-scheduler", name = "enabled", havingValue = "true", matchIfMissing = true)
class JobRunrConfig {

  @Bean
  @SuppressWarnings("deprecated")
  RestHighLevelClient restHighLevelClient(final RestClient client) {
    return new RestHighLevelClientBuilder(client).build();
  }
}

[jloisel]

We currently use Quartz along with a postgres database. We already have Elasticsearch to store the majority of our data. By switching from Quartz to JobRunr, we can get rid of quartz and the postgresql database.

[rdehuyss]

I must confess that Elastic currently is not used by many installations in production - Most people use Postgres.

[jloisel]

Completely understandable, Elasticsearch is rarely used as the main datastore.

[rdehuyss]

Solved in branch 6.4.