Reindex

Copy documents from one index to another

curl -X POST http://localhost:9200/_reindex -H 'Content-Type: application/json' -d '{"source":{"index":"old"},"dest":{"index":"new"}}'

More elasticsearch commands

Force merge index

curl -X POST 'http://localhost:9200/<index>/_forcemerge?max_num_segments=1'

Reduce segment count; useful before making index read-only
Node stats

curl -s http://localhost:9200/_cat/nodes?v

Show all ES nodes with JVM heap, load, roles
Search query

curl -s -X POST http://localhost:9200/<index>/_search -H 'Content-Type: application/json' -d '{"query":{"match":{"message":"error"}}}'

Full-text search for documents matching a term
Snapshot create

curl -X PUT http://localhost:9200/_snapshot/<repo>/<snapshot>

Create a snapshot to the registered repository
ILM explain index

curl -s 'http://localhost:9200/<index>/_ilm/explain' | jq '.indices | to_entries[] | {index:.key, phase:.value.phase, action:.value.action}'

Show current ILM lifecycle phase and action for an index