Elasticsearch Reference Card

1 OVERVIEW

• get version and details

curl -XGET 'http://localhost:9200'

2 CLUSTER

curl 'http://localhost:9200/_cluster/health?pretty'
curl 'http://localhost:9200/_cluster/health?wait_for_status=yellow&timeout=50s&pretty'
curl 'http://localhost:9200/_cluster/state?pretty'
curl 'http://localhost:9200/_cluster/stats?human&pretty'
curl 'http://localhost:9200/_cluster/pending_tasks?pretty'

• full settings

curl 'http://localhost:9200/_cluster/settings?include_defaults=true&flat_settings=true&pretty'

2.1 Disk filling

Add or modify the following lines in `elasticsearch.yml` to set the desired disk watermark levels and their corresponding percentages:

cluster.routing.allocation.disk.watermark.low: 85%
cluster.routing.allocation.disk.watermark.high: 90%
cluster.routing.allocation.disk.watermark.flood_stage: 95%

• low

Elasticsearch starts allocating new shards to nodes with disk usage below this level.

• high

Elasticsearch starts throttling shard allocations to nodes with disk usage above this level.

• flood_stage

Elasticsearch prevents shard allocations on nodes with disk usage above this level.

• check current settings with:

curl -s 'http://localhost:9200/_cluster/settings?include_defaults=true&flat_settings=true&pretty' | grep watermark

3 ADMIN

• force a synced flush

curl -XPOST 'localhost:9200/_flush/synced'

• Change the number of shards being recovered simultaneously per node

curl -XPUT localhost:9200/_cluster/settings -d '{
"transient" :{
"cluster.routing.allocation.exclude._ip" : "1.2.3.4"
}
}';echo

• Change the recovery speed

curl -XPUT localhost:9200/_cluster/settings -d '{
"transient" :{
"indices.recovery.max_bytes_per_sec" : "80mb"
}
}';echo

• Change the number of concurrent streams for a recovery on a single node

curl -XPUT localhost:9200/_cluster/settings -d '{
"transient" :{
"indices.recovery.concurrent_streams" : 6
}
}';echo

4 NODE

• get infos

curl 'http://localhost:9200/_nodes?pretty'
curl 'http://localhost:9200/_nodes/stats?pretty'
curl 'http://localhost:9200/_nodes/nodeId1,nodeId2/stats?pretty'
curl 'http://localhost:9200/_cat/nodes?v=true'

• remove nodes from clusters gracefully

curl -XPUT localhost:9200/_cluster/settings -d '{
"transient" :{
"cluster.routing.allocation.exclude._ip" : "1.2.3.4"
}
}';echo

5 INDICES

• list

curl -X GET 'http://localhost:9200/_cat/indices?v'

• delete

curl -X DELETE 'http://localhost:9200/examples'

• back up

curl -XPOST --header 'Content-Type: application/json' http://localhost:9200/_reindex -d '{
  "source": {
    "index1": "someexamples"
  },
  "dest": {
    "index2": "someexamples_copy"
  }
}'

• change replica count of an Indice

curl -XPUT --header 'Content-Type: application/json' 'http://localhost:9200/_index_name_/_settings' -d '{
  "index" : {
    "number_of_replicas" : 1
  }
}'

• change replica count of all indices

curl -X PUT "127.0.0.1:9200/.*/_settings" -H 'Content-Type: application/json' -d'{ "index" : { "number_of_replicas" : 0 } }'

• list all docs in an index

curl -X GET 'http://localhost:9200/elasticsearch_query_examples/_search'

5.1 Debug Single Node Replica issues

rpm -q opensearch
   opensearch-2.19.0-1.x86_64


curl -s -XGET localhost:9200/_cat/indices | grep  yell
   yellow open top_queries-2025.02.22-91903 8dXcpNv9QTyciYQCVzKmkQ 1 1      4433 1522  11.8mb  11.8mb
   yellow open top_queries-2025.02.23-91904 CFNMBEGBSnieQ5oYsM3Q8g 1 1      7127 1513  16.1mb  16.1mb


curl -s -X GET "localhost:9200/_cluster/settings?include_defaults=true&flat_settings=true" | jq '.defaults."cluster.default_number_of_replicas"'
   "1"

vim /etc/opensearch/opensearch.yml
---
cluster.default_number_of_replicas: 0
---

systemctl restart opensearch


curl -s -X GET "localhost:9200/_cluster/settings?include_defaults=true&flat_settings=true" | jq '.defaults."cluster.default_number_of_replicas"'
  "0"

curl https://raw.githubusercontent.com/joe-speedboat/linux.scripts/refs/heads/master/shell/opensearch_template_replica_debug.sh | bash

curl -X PUT "127.0.0.1:9200/top_queries-*/_settings" -H 'Content-Type: application/json' -d'
{
  "index": {
    "number_of_replicas": 0
  }
}'


curl -s -XGET localhost:9200/_cat/indices | grep  top_quer
  green open top_queries-2025.02.22-91903 8dXcpNv9QTyciYQCVzKmkQ 1 0      4433 1522  11.8mb  11.8mb
  green open top_queries-2025.02.23-91904 CFNMBEGBSnieQ5oYsM3Q8g 1 0      7127 1513  16.1mb  16.1mb

6 SHRADS

• list shrads

curl -XGET localhost:9200/_cat/shards?v

• show details of a shard

curl -X GET 'http://localhost:9200/_cat/shards/graylog_39?v'

• move shards from one node to another

curl -XPOST 'http://localhost:9200/_cluster/reroute' -d '{
"commands" : [
{
"move" :
{
"index" : "indexname", "shard" : 1,
"from_node" : "nodename", "to_node" : "nodename"
}
}
]
}';echo

• force the allocation of an unassigned shard with a reason

curl -XPOST 'http://localhost:9200/_cluster/reroute?explain' -d '{
"commands" : [ {
"allocate" : {
"index" : "indexname", "shard" : 0, "node" : "nodename"
}
} ]
}';echo

6.1 Delete Unassigned Shrads

curl http://localhost:9200/_cluster/health?pretty
curl -XGET localhost:9200/_cat/shards?h=index,shard,prirep,state,unassigned.reason
curl -XGET http://localhost:9200/_cat/shards | grep UNASSIGNED | awk {'print $1'} | xargs -i curl -XDELETE "http://localhost:9200/{}"
curl -XGET localhost:9200/_cat/shards?h=index,shard,prirep,state,unassigned.reason
curl http://localhost:9200/_cluster/health?pretty