Shrink Shards Of a Index in Elasticsearch

To shrink a shard in elasticsearch we already have a “/old_index/_shrink/new_index” endpoint , which creates a new index with less shards. An example of endpoint request :

# Tested Using Elasticsearch 6.5
#for kibana
POST old_index/_shrink/new_index?copy_settings=true
{
 “settings”: {
 “index.routing.allocation.require._name”: null, 
 “index.blocks.write”: null,
 “index.number_of_replicas”: 1,
 “index.number_of_shards”: 1, 
 “index.codec”: “best_compression” 
 },
 “aliases”: {
 “my_search_indices”: {}
 }
}
#curl
curl -XPOST -H "Content-type:application/json" localhost:9200/old_index/_shrink/new_index?copy_settings=true -d '{"settings": {"index.blocks.write": null,"index.number_of_replicas": 1,"index.number_of_shards": 1, "index.codec": "best_compression" },"aliases": {"my_search_indices": {}}}'

after this execution you would have two indexes with same number of documents and mappings but with different shards and replicas.

Sometimes problem occurs like:

• Read only index required or should be not writable
• The index must be read-only.
• FORBIDDEN/12/index read-only / allow delete

Then first run the below request:

#for kibana
PUT old_index/_settings
{
 “settings”: {
 “index.blocks.write”: false,
 “index.blocks.read_only_allow_delete”: null
}
}
#curl
curl -XPUT -H "Content-type:application/json" localhost:9200/old_index/_settings -d '{"settings": {"index.blocks.write": true,"index.blocks.read_only_allow_delete": null }}'

Verify the documents in new_index , and when you are sure its ok then you can delete the old index by requesting:

#kibana
DELETE old_index
#curl
curl -XDELETE localhost:9200/old_index

Github: https://github.com/bazingarj/elasticsearch-shrink-index-shards/tree/master