cat APIs
editcat APIs
editIntroduction
editJSON 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 an ssh terminal, need compact and aligned text. The cat API aims to meet this need.
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
editVerbose
editEach of the commands accepts a query string parameter v
to turn on
verbose output. For example:
GET /_cat/master?v
Might respond with:
id host ip node u_n93zwxThWHi1PDBJAGAg 127.0.0.1 127.0.0.1 u_n93zw
Help
editEach of the commands accepts a query string parameter help
which will
output its available columns. For example:
GET /_cat/master?help
Might respond with:
id | | node id host | h | host name ip | | ip address node | n | node name
help
is not supported if any optional url parameter is used.
For example GET _cat/shards/twitter?help
or GET _cat/indices/twi*?help
results in an error. Use GET _cat/shards?help
or GET _cat/indices?help
instead.
Headers
editEach of the commands accepts a query string parameter h
which forces
only those columns to appear. For example:
GET /_cat/nodes?h=ip,port,heapPercent,name
Responds with:
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
editMany 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. We only need to tweak two things. First, we want to turn
off human mode. We’ll use a byte-level resolution. Then we’ll pipe
our output into sort
using the appropriate column, which in this
case is the eighth one.
% curl '192.168.56.10:9200/_cat/indices?bytes=b' | sort -rnk8 green wiki2 3 0 10000 0 105274918 105274918 green wiki1 3 0 10000 413 103776272 103776272 green foo 1 0 227 0 2065131 2065131
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
edit% curl 'localhost:9200/_cat/indices?format=json&pretty' [ { "pri.store.size": "650b", "health": "yellow", "status": "open", "index": "twitter", "pri": "5", "rep": "1", "docs.count": "0", "docs.deleted": "0", "store.size": "650b" } ]
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:
% curl '192.168.56.10:9200/_cat/indices?pretty' -H "Accept: application/json" [ { "pri.store.size": "650b", "health": "yellow", "status": "open", "index": "twitter", "pri": "5", "rep": "1", "docs.count": "0", "docs.deleted": "0", "store.size": "650b" } ]
Sort
editEach 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.
GET _cat/templates?v&s=order:desc,index_patterns
returns:
name index_patterns order version pizza_pepperoni [*pepperoni*] 2 sushi_california_roll [*avocado*] 1 1 pizza_hawaiian [*pineapples*] 1