I am new to ES and trying to upgrade ES from 2.3 to 7.8. The following lines of code containing NodeBuilder are deprecated.
import org.elasticsearch.common.settings.Settings;
import org.elasticsearch.node.NodeBuilder;
Settings settings = Settings.builder().loadFromPath(Paths.get("config/elasticsearch.yml").toAbsolutePath()).build();
NodeBuilder.nodeBuilder().settings(settings).node();
What would be a good way to replace that NodeBuilder?
That code is running an "embedded" Elasticsearch node, a mode which is no longer supported (for ~4 years). The only supported way to run Elasticsearch is as a standalone server process (or a cluster of the same) and to interact with it via its client APIs.
Any more detailed clues on the simplest code to start a connection with ES 7.8 on the local machine using Java API would be welcome. I am currently reading up the https://www.elastic.co/guide/en/elasticsearch/client/java-rest/7.8/index.html
Those are the right docs to look at, yes. The "getting started" section should get you started, particularly this page.