Useful for finding field names from large schemas:
╭─{ rye@perhaps:~/src/elastic/scratch/ecs-20240517 } ╰─○ ./flatten_elasticsearch_legacy_template.rb < "${ecs_source?:}/generated/elasticsearch/legacy/template.json" | grep -e '\bip\b' client.ip client.nat.ip destination.ip destination.nat.ip host.ip observer.ip orchestrator.resource.ip process.entry_leader.entry_meta.source.ip related.ip server.ip server.nat.ip source.ip source.nat.ip threat.enrichments.indicator.ip threat.indicator.ip [success]