Rollover Indexedit

The rollover index API rolls an alias to a new index when the existing index meets a condition you provide. You can use this API to retire an index that becomes too large or too old.

Note

To roll over an index, a condition must be met when you call the API. Elasticsearch does not monitor the index after you receive an API response. To automatically roll over indices when a condition is met, you can use Elasticsearch’s index lifecycle management (ILM) policies.

The API accepts a single alias name and a list of conditions. The alias must point to a write index for a Rollover request to be valid. There are two ways this can be achieved, and depending on the configuration, the alias metadata will be updated differently. The two scenarios are as follows:

  • The alias only points to a single index with is_write_index not configured (defaults to null).

In this scenario, the original index will have their rollover alias will be added to the newly created index, and removed from the original (rolled-over) index.

  • The alias points to one or more indices with is_write_index set to true on the index to be rolled over (the write index).

In this scenario, the write index will have its rollover alias' is_write_index set to false, while the newly created index will now have the rollover alias pointing to it as the write index with is_write_index as true.

The available conditions are:

Table 30. conditions parameters

NameDescription

max_age

The maximum age of the index

max_docs

The maximum number of documents the index should contain. This does not add documents multiple times for replicas

max_size

The maximum estimated size of the primary shard of the index

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

# Add > 1000 documents to logs-000001

POST /logs_write/_rollover 
{
  "conditions": {
    "max_age":   "7d",
    "max_docs":  1000,
    "max_size":  "5gb"
  }
}

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, or has an index size at least around 5GB, 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,
    "[max_size: 5gb]": false,
  }
}

Whether the index was rolled over.

Whether the rollover was dry run.

The result of each condition.

Naming the new indexedit

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,
    "max_size": "5gb"
  }
}

Using date math with the rollover APIedit

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/_doc/1
{
  "message": "a dummy log"
}

POST logs_write/_refresh

# 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 indexedit

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,
    "max_size": "5gb"
  },
  "settings": {
    "index.number_of_shards": 2
  }
}

Dry runedit

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,
    "max_size": "5gb"
  }
}

Wait For Active Shardsedit

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.

Write Index Alias Behavioredit

The rollover alias when rolling over a write index that has is_write_index explicitly set to true is not swapped during rollover actions. Since having an alias point to multiple indices is ambiguous in distinguishing which is the correct write index to roll over, it is not valid to rollover an alias that points to multiple indices. For this reason, the default behavior is to swap which index is being pointed to by the write-oriented alias. This was logs_write in some of the above examples. Since setting is_write_index enables an alias to point to multiple indices while also being explicit as to which is the write index that rollover should target, removing the alias from the rolled over index is not necessary. This simplifies things by allowing for one alias to behave both as the write and read aliases for indices that are being managed with Rollover.

Look at the behavior of the aliases in the following example where is_write_index is set on the rolled over index.

PUT my_logs_index-000001
{
  "aliases": {
    "logs": { "is_write_index": true } 
  }
}

PUT logs/_doc/1
{
  "message": "a dummy log"
}

POST logs/_refresh

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

PUT logs/_doc/2 
{
  "message": "a newer log"
}

configures my_logs_index as the write index for the logs alias

newly indexed documents against the logs alias will write to the new index

{
  "_index" : "my_logs_index-000002",
  "_type" : "_doc",
  "_id" : "2",
  "_version" : 1,
  "result" : "created",
  "_shards" : {
    "total" : 2,
    "successful" : 1,
    "failed" : 0
  },
  "_seq_no" : 0,
  "_primary_term" : 1
}

After the rollover, the alias metadata for the two indices will have the is_write_index setting reflect each index’s role, with the newly created index as the write index.

{
  "my_logs_index-000002": {
    "aliases": {
      "logs": { "is_write_index": true }
    }
  },
  "my_logs_index-000001": {
    "aliases": {
      "logs": { "is_write_index" : false }
    }
  }
}