Rollover Index

The rollover index API rolls an alias over to a new index when the existing index is considered to be too large or too old.

The API accepts a single alias name and a list of conditions. The alias must point to a single index only. If the index satisfies the specified conditions then a new index is created and the alias is switched to point to the new index.

PUT /logs-000001 
{
  "aliases": {
    "logs_write": {}
  }
}

# Add > 1000 documents to logs-000001

POST /logs_write/_rollover 
{
  "conditions": {
    "max_age":   "7d",
    "max_docs":  1000
  }
}

Creates an index called logs-0000001 with the alias logs_write.

If the index pointed to by logs_write was created 7 or more days ago, or contains 1,000 or more documents, then the logs-000002 index is created and the logs_write alias is updated to point to logs-000002.

The above request might return the following response:

{
  "acknowledged": true,
  "shards_acknowledged": true,
  "old_index": "logs-000001",
  "new_index": "logs-000002",
  "rolled_over": true, 
  "dry_run": false, 
  "conditions": { 
    "[max_age: 7d]": false,
    "[max_docs: 1000]": true
  }
}

Whether the index was rolled over.

Whether the rollover was dry run.

The result of each condition.

Naming the new index

If the name of the existing index ends with - and a number — e.g. logs-000001 — then the name of the new index will follow the same pattern, incrementing the number (logs-000002). The number is zero-padded with a length of 6, regardless of the old index name.

If the old name doesn’t match this pattern then you must specify the name for the new index as follows:

POST /my_alias/_rollover/my_new_index_name
{
  "conditions": {
    "max_age":   "7d",
    "max_docs":  1000
  }
}

Using date math with the rolllover API

It can be useful to use date math to name the rollover index according to the date that the index rolled over, e.g. logstash-2016.02.03. The rollover API supports date math, but requires the index name to end with a dash followed by a number, e.g. logstash-2016.02.03-1 which is incremented every time the index is rolled over. For instance:

# PUT /<logs-{now/d}-1> with URI encoding:
PUT /%3Clogs-%7Bnow%2Fd%7D-1%3E 
{
  "aliases": {
    "logs_write": {}
  }
}

PUT logs_write/log/1
{
  "message": "a dummy log"
}

# Wait for a day to pass

POST /logs_write/_rollover 
{
  "conditions": {
    "max_docs":   "1"
  }
}

Creates an index named with today’s date (e.g.) logs-2016.10.31-1

Rolls over to a new index with today’s date, e.g. logs-2016.10.31-000002 if run immediately, or logs-2016.11.01-000002 if run after 24 hours

These indices can then be referenced as described in the date math documentation. For example, to search over indices created in the last three days, you could do the following:

# GET /<logs-{now/d}-*>,<logs-{now/d-1d}-*>,<logs-{now/d-2d}-*>/_search
GET /%3Clogs-%7Bnow%2Fd%7D-*%3E%2C%3Clogs-%7Bnow%2Fd-1d%7D-*%3E%2C%3Clogs-%7Bnow%2Fd-2d%7D-*%3E/_search

Defining the new index

The settings, mappings, and aliases for the new index are taken from any matching index templates. Additionally, you can specify settings, mappings, and aliases in the body of the request, just like the create index API. Values specified in the request override any values set in matching index templates. For example, the following rollover request overrides the index.number_of_shards setting:

PUT /logs-000001
{
  "aliases": {
    "logs_write": {}
  }
}

POST /logs_write/_rollover
{
  "conditions" : {
    "max_age": "7d",
    "max_docs": 1000
  },
  "settings": {
    "index.number_of_shards": 2
  }
}

Dry run

The rollover API supports dry_run mode, where request conditions can be checked without performing the actual rollover:

PUT /logs-000001
{
  "aliases": {
    "logs_write": {}
  }
}

POST /logs_write/_rollover?dry_run
{
  "conditions" : {
    "max_age": "7d",
    "max_docs": 1000
  }
}

Wait For Active Shards

Because the rollover operation creates a new index to rollover to, the wait_for_active_shards setting on index creation applies to the rollover action as well.