Index State Management in Amazon OpenSearch Service

Index State Management (ISM) in Amazon OpenSearch Service lets you define custom management policies that automate routine tasks, and apply them to indexes and index patterns. You no longer need to set up and manage external processes to run your index operations.

A policy contains a default state and a list of states for the index to transition between. Within each state, you can define a list of actions to perform and conditions that trigger these transitions. A typical use case is to periodically delete old indexes after a certain period of time. For example, you can define a policy that moves your index into a read_only state after 30 days and then ultimately deletes it after 90 days.

After you attach a policy to an index, ISM creates a job that runs every 5 to 8 minutes (or 30 to 48 minutes for pre-1.3 clusters) to perform policy actions, check conditions, and transition the index into different states. The base time for this job to run is every 5 minutes, plus a random 0-60% jitter is added to it to make sure you do not see a surge of activity from all your indexes at the same time. ISM doesn't run jobs if the cluster state is red.

ISM requires OpenSearch or Elasticsearch 6.8 or later.

Create an ISM policy

Sample policies

The following sample policies demonstrate how to automate common ISM use cases.

Hot to warm to cold storage

This sample policy moves an index from hot storage to UltraWarm, and eventually to
 cold storage. Then, it deletes the index.

The index is initially in the hot state. After ten days, ISM moves it
 to the warm state. 80 days later, after the index is 90 days old, ISM moves the index to the
 cold state. After a year, the service sends a notification to an Amazon Chime room that the index is being deleted and then permanently deletes it.

Note that cold indexes require the cold_delete operation rather than the normal delete operation. Also note that an explicit timestamp_field is required in your data in order to manage cold indexes with ISM.

{
  "policy": {
    "description": "Demonstrate a hot-warm-cold-delete workflow.",
    "default_state": "hot",
    "schema_version": 1,
    "states": [{
        "name": "hot",
        "actions": [],
        "transitions": [{
          "state_name": "warm",
          "conditions": {
            "min_index_age": "10d"
          }
        }]
      },
      {
        "name": "warm",
        "actions": [{
          "warm_migration": {},
          "retry": {
            "count": 5,
            "delay": "1h"
          }
        }],
        "transitions": [{
          "state_name": "cold",
          "conditions": {
            "min_index_age": "90d"
          }
        }]
      },
      {
        "name": "cold",
        "actions": [{
            "cold_migration": {
              "timestamp_field": "<your timestamp field>"
            }
          }
        ],
        "transitions": [{
          "state_name": "delete",
          "conditions": {
             "min_index_age": "365d"
          }
        }]
      },
      {
        "name": "delete",
        "actions": [{
          "notification": {
            "destination": {
              "chime": {
                "url": "<URL>"
              }
            },
            "message_template": {
              "source": "The index {{ctx.index}} is being deleted."
            }
          }
        },
        {
          "cold_delete": {}
        }]
      }
    ]
  }
}

Reduce replica count

This sample policy reduces replica count to zero after seven days to conserve disk space and then deletes the index after 21 days. This policy assumes your index is non-critical and no longer receiving write requests; having zero replicas carries some risk of data loss.

{
  "policy": {
    "description": "Changes replica count and deletes.",
    "schema_version": 1,
    "default_state": "current",
    "states": [{
        "name": "current",
        "actions": [],
        "transitions": [{
          "state_name": "old",
          "conditions": {
            "min_index_age": "7d"
          }
        }]
      },
      {
        "name": "old",
        "actions": [{
          "replica_count": {
            "number_of_replicas": 0
          }
        }],
        "transitions": [{
          "state_name": "delete",
          "conditions": {
            "min_index_age": "21d"
          }
        }]
      },
      {
        "name": "delete",
        "actions": [{
          "delete": {}
        }],
        "transitions": []
      }
    ]
  }
}

Take an index snapshot

This sample policy uses the snapshot operation to take a snapshot of an index as soon as it contains at least one document. repository is the name of the manual snapshot repository you registered in Amazon S3. snapshot is the name of the snapshot. For snapshot prerequisites and steps to register a repository, see Creating index snapshots in Amazon OpenSearch Service.

{
  "policy": {
    "description": "Takes an index snapshot.",
    "schema_version": 1,
    "default_state": "empty",
    "states": [{
        "name": "empty",
        "actions": [],
        "transitions": [{
          "state_name": "occupied",
          "conditions": {
            "min_doc_count": 1
          }
        }]
      },
      {
        "name": "occupied",
        "actions": [{
          "snapshot": {
            "repository": "<my-repository>",
            "snapshot": "<my-snapshot>"
            }
          }],
          "transitions": []
      }
    ]
  }
}

ISM templates

You can set up an ism_template field in a policy so when you create an index that matches the template pattern, the policy is automatically attached to that index. In this example, any index you create with a name that begins with "log" is automatically matched to the ISM policy my-policy-id:

PUT _plugins/_ism/policies/my-policy-id
{
  "policy": {
    "description": "Example policy.",
    "default_state": "...",
    "states": [...],
    "ism_template": {
      "index_patterns": ["log*"],
      "priority": 100
    }
  }
}

For a more detailed example, see Sample policy with ISM template for auto rollover.

Differences

Compared to OpenSearch and Elasticsearch, ISM for Amazon OpenSearch Service has several differences.

ISM operations

Cold storage ISM operations

For cold indexes, you must specify a ?type=_cold parameter when you use the following ISM APIs:

These APIs for cold indexes have the following additional differences:

ISM settings

OpenSearch and Elasticsearch let you change all available ISM settings using the _cluster/settings API. On Amazon OpenSearch Service, you can only change the following ISM settings: