CAT API
Introduced 1.0
You can get essential statistics about your cluster in an easy-to-understand, tabular format using the compact and aligned text (CAT) API. The CAT API is a human-readable interface that returns plain text instead of traditional JSON.
Using the CAT API, you can answer questions like which node is the elected master, what state is the cluster in, how many documents are in each index, and so on.
Example
To see the available operations in the CAT API, use the following command:
GET _cat
The response is an ASCII cat (=^.^=) and a list of operations:
=^.^=
/_cat/allocation
/_cat/segment_replication
/_cat/segment_replication/{index}
/_cat/shards
/_cat/shards/{index}
/_cat/cluster_manager
/_cat/nodes
/_cat/tasks
/_cat/indices
/_cat/indices/{index}
/_cat/segments
/_cat/segments/{index}
/_cat/count
/_cat/count/{index}
/_cat/recovery
/_cat/recovery/{index}
/_cat/health
/_cat/pending_tasks
/_cat/aliases
/_cat/aliases/{alias}
/_cat/thread_pool
/_cat/thread_pool/{thread_pools}
/_cat/plugins
/_cat/fielddata
/_cat/fielddata/{fields}
/_cat/nodeattrs
/_cat/repositories
/_cat/snapshots/{repository}
/_cat/templates
/_cat/pit_segments
/_cat/pit_segments/{pit_id}
Optional query parameters
The root _cat API does not take any parameters, but individual APIs, such as /_cat/nodes accept the following query parameters.
| Parameter | Description |
|---|---|
v | Provides verbose output by adding headers to the columns. It also adds some formatting to help align each of the columns together. All examples in this section include the v parameter. |
help | Lists the default and other available headers for a given operation. |
h | Limits the output to specific headers. |
format | The format in which to return the result. Valid values are json, yaml, cbor, and smile. |
s | Sorts the output by the specified columns. |
Query parameter usage examples
You can specify a query parameter to any CAT operation to obtain more specific results.
Get verbose output
To query aliases and get verbose output that includes all column headings in the response, use the v query parameter.
GET _cat/aliases?v
The response provides more details, such as names of each column in the response.
alias index filter routing.index routing.search is_write_index
.kibana .kibana_1 - - - -
sample-alias1 sample-index-1 - - - -
Without the verbose parameter, v, the response simply returns the alias names:
.kibana .kibana_1 - - - -
sample-alias1 sample-index-1 - - - -
Get all available headers
To see all the available headers, use the help parameter:
GET _cat/<operation_name>?help
For example, to see the available headers for the CAT aliases operation, send the following request:
GET _cat/aliases?help
The response contains the available headers:
alias | a | alias name
index | i,idx | index alias points to
filter | f,fi | filter
routing.index | ri,routingIndex | index routing
routing.search | rs,routingSearch | search routing
is_write_index | w,isWriteIndex | write index
Get a subset of headers
To limit the output to a subset of headers, use the h parameter:
GET _cat/<operation_name>?h=<header_name_1>,<header_name_2>&v
For example, to limit aliases to only the alias name and index, send the following request:
GET _cat/aliases?h=alias,index
The response contains the requested information:
.kibana .kibana_1
sample-alias1 sample-index-1
Typically, for any operation you can find out what headers are available using the help parameter, and then use the h parameter to limit the output to only the headers that you care about.
Sort by a header
To sort the output by a header, use the s parameter:
GET _cat/<operation_name>?s=<header_name_1>,<header_name_2>
For example, to sort aliases by alias and then index, send the following request:
GET _cat/aliases?s=i,a
The response contains the requested information:
sample-alias2 sample-index-1
sample-alias1 sample-index-2
Retrieve data in JSON format
By default, CAT APIs return data in text/plain format.
To retrieve data in JSON format, use the format=json parameter:
GET _cat/<operation_name>?format=json
For example, to retrieve aliases in JSON format, send the following request:
GET _cat/aliases?format=json
The response contains data in JSON format:
[
{"alias":".kibana","index":".kibana_1","filter":"-","routing.index":"-","routing.search":"-","is_write_index":"-"},
{"alias":"sample-alias-1","index":"sample-index-1","filter":"-","routing.index":"-","routing.search":"-","is_write_index":"-"}
]
Other supported formats are YAML, CBOR, and Smile.
If you use the Security plugin, make sure you have the appropriate permissions.