cat APIs

Introduction

JSON is great…​ for computers. Even if it’s pretty-printed, trying to find relationships in the data is tedious. Human eyes, especially when looking at a terminal, need compact and aligned text. The cat APIs aim to meet this need.

cat APIs are only intended for human consumption using the Kibana console or command line. They are not intended for use by applications. For application consumption, we recommend using a corresponding JSON API.

All the cat commands accept a query string parameter help to see all the headers and info they provide, and the /_cat command alone lists all the available commands.

Common parameters

Verbose

Each of the commands accepts a query string parameter v to turn on verbose output. For example:

  1. GET /_cat/master?v

Might respond with:

  1. id                     host      ip        node
  2. u_n93zwxThWHi1PDBJAGAg 127.0.0.1 127.0.0.1 u_n93zw

Help

Each of the commands accepts a query string parameter help which will output its available columns. For example:

  1. GET /_cat/master?help

Might respond with:

  1. id   |   | node id
  2. host | h | host name
  3. ip   |   | ip address
  4. node | n | node name

help is not supported if any optional url parameter is used. For example GET _cat/shards/my-index-000001?help or GET _cat/indices/my-index-*?help results in an error. Use GET _cat/shards?help or GET _cat/indices?help instead.

Headers

Each of the commands accepts a query string parameter h which forces only those columns to appear. For example:

  1. GET /_cat/nodes?h=ip,port,heapPercent,name

Responds with:

  1. 127.0.0.1 9300 27 sLBaIGK

You can also request multiple columns using simple wildcards like /_cat/thread_pool?h=ip,queue* to get all headers (or aliases) starting with queue.

Numeric formats

Many commands provide a few types of numeric output, either a byte, size or a time value. By default, these types are human-formatted, for example, 3.5mb instead of 3763212. The human values are not sortable numerically, so in order to operate on these values where order is important, you can change it.

Say you want to find the largest index in your cluster (storage used by all the shards, not number of documents). The /_cat/indices API is ideal. You only need to add three things to the API request:

  1. The bytes query string parameter with a value of b to get byte-level resolution.
  2. The s (sort) parameter with a value of store.size:desc to sort the output by shard storage in descending order.
  3. The v (verbose) parameter to include column headings in the response.
  1. GET /_cat/indices?bytes=b&s=store.size:desc&v

The API returns the following response:

  1. health status index            uuid                   pri rep docs.count docs.deleted store.size pri.store.size
  2. yellow open   my-index-000001  u8FNjxh8Rfy_awN11oDKYQ   1   1       1200            0      72171         72171
  3. green  open   my-index-000002  nYFWZEO7TUiOjLQXBaYJpA   1   0          0            0        230          230

If you want to change the time units, use time parameter.

If you want to change the size units, use size parameter.

If you want to change the byte units, use bytes parameter.

Response as text, json, smile, yaml or cbor

  1. % curl 'localhost:9200/_cat/indices?format=json&pretty'
  2. [
  3.   {
  4.     "pri.store.size": "650b",
  5.     "health": "yellow",
  6.     "status": "open",
  7.     "index": "my-index-000001",
  8.     "pri": "5",
  9.     "rep": "1",
  10.     "docs.count": "0",
  11.     "docs.deleted": "0",
  12.     "store.size": "650b"
  13.   }
  14. ]

Currently supported formats (for the ?format= parameter): - text (default) - json - smile - yaml - cbor

Alternatively you can set the “Accept” HTTP header to the appropriate media format. All formats above are supported, the GET parameter takes precedence over the header. For example:

  1. % curl '192.168.56.10:9200/_cat/indices?pretty' -H "Accept: application/json"
  2. [
  3.   {
  4.     "pri.store.size": "650b",
  5.     "health": "yellow",
  6.     "status": "open",
  7.     "index": "my-index-000001",
  8.     "pri": "5",
  9.     "rep": "1",
  10.     "docs.count": "0",
  11.     "docs.deleted": "0",
  12.     "store.size": "650b"
  13.   }
  14. ]

Sort

Each of the commands accepts a query string parameter s which sorts the table by the columns specified as the parameter value. Columns are specified either by name or by alias, and are provided as a comma separated string. By default, sorting is done in ascending fashion. Appending :desc to a column will invert the ordering for that column. :asc is also accepted but exhibits the same behavior as the default sort order.

For example, with a sort string s=column1,column2:desc,column3, the table will be sorted in ascending order by column1, in descending order by column2, and in ascending order by column3.

  1. GET _cat/templates?v&s=order:desc,index_patterns

returns:

  1. name                  index_patterns order version
  2. pizza_pepperoni       [*pepperoni*]  2
  3. sushi_california_roll [*avocado*]    1     1
  4. pizza_hawaiian        [*pineapples*] 1