Elasticsearch

Some tips to work with Elasticsearch using its REST interface.

In the examples below, let’s assume that the url of the Elasticsearch instance is https://elasticurl. Remember that the full format for these urls, when they are protected by simple HTTP authentication (user and password), and are accessible through a non-root resource, is something like:

https://user:passwd@host:port/resource

Working with indexes

To list all indexex stored by Elasticsearch:

$ curl -XGET 'https://elasticurl/_cat/indices?v'

This returns for each index, its name, status (open comes to mean ‘usable’), number of documents, deleted documents, and storage size used.

Working with aliases

Elasticsearch index aliases allow to work with a collection of indexes as if it were just a single index, or with a single index under a different name. In the following, we were refer as ‘base indexes’ to the real indexes for which we will create aliases. Find more information about working with aliases in the Elasticsearch manual.

To list the base indexes corresponding to an index alias (assume the index alias is alias_index):

$ curl -XGET  'https://elastic_url/alias_index/_alias/*'

The result will be similar to (being base_index the base index for the alias, and alias_index, alias_index2 two aliases for that base index):

{
  "base_index" : {
    "aliases" : {
      "alias_index" : { },
      "alias_index2" : { }
    }
  }
}

To remove aliases, and create new ones, in an atomic operation:

curl -XPOST 'https://elastic_url/_aliases' -d '
{
    "actions" : [
        { "add" : { "index" : "base_index", "alias" : "alias_index" } },
        { "add" : { "index" : "base_index2", "alias" : "alias_index" } },
        { "remove" : { "index" : "old_base_index", "alias" : "alias_index" } },
        { "remove" : { "index" : "old_base_index", "alias" : "alias_index" } }
    ]
}'