1. Rollover index policy with deletion of indices when the doc count exceeds a certain value.
1.1. Create an ISM policy

curl -X PUT "localhost:9200/_plugins/_ism/policies/rollover_policy?pretty" -H 'Content-Type: application/json' -d'
{
  "policy": {
    "description": "Example rollover policy.",
    "default_state": "rollover",
    "states": [
      {
        "name": "rollover",
        "actions": [
          {
            "rollover": {
              "min_doc_count": 1
            }
          }
        ],
        "transitions": [{
            "state_name": "alias",
            "conditions": {
              "min_doc_count": "2"
            }
          }]
      },
      {
        "name": "alias",
        "actions": [
          {
            "alias": {
              "actions": [
                {
                  "remove": {
                      "alias": "log"
                  }
                }
              ]
            }
          }
        ]
      }
    ],
    "ism_template": {
      "index_patterns": ["log*"],
      "priority": 100
    }
  }
}
'

1.2 Create an index template to enable the policy on:

curl -X PUT "localhost:9200/_index_template/ism_rollover?" -H 'Content-Type: application/json' -d'
{
  "index_patterns": ["log*"],
  "template": {
   "settings": {
    "plugins.index_state_management.rollover_alias": "log"
   }
 }
}
'

1.3 Change the cluster settings to trigger jobs every minute:

curl -X PUT "localhost:9200/_cluster/settings?pretty=true" -H 'Content-Type: application/json' -d'
{
  "persistent" : {
    "plugins.index_state_management.job_interval" : 1
  }
}
'

1.4 Create a new index:

curl -X PUT "localhost:9200/log-000001" -H 'Content-Type: application/json' -d'
{
  "aliases": {
    "log": {
      "is_write_index": true
    }
  }
}
'

1.5 Add a document to the index to trigger the job:

curl -X POST "localhost:9200/log-000001/_doc" -H 'Content-Type: application/json' -d'
{
  "message": "dummy"
}
'

1.6 The first job will trigger the rollover action and a new index will be created.
1.7 Add another document to the two indices like step 1.5.
1.8 The new job will cause the second index to point to the log alias and the older one will be removed due to alias action.
1.9. Verify these steps using alias and index API:

curl -X GET "localhost:9200/_cat/indices?pretty"

curl -X GET "localhost:9200/_cat/aliases?pretty"


2. Fail the case if a user tries to apply alias action on a specific index/indices.
2.1 Create the following policy:

curl -X PUT "localhost:9200/_plugins/_ism/policies/remove_action_policy?pretty" -H 'Content-Type: application/json' -d'
{
  "policy": {
    "description": "Example remove action policy.",
    "default_state": "alias",
    "states": [
      {
        "name": "alias",
        "actions": [
          {
            "alias": {
              "actions": [
                {
                  "add": {
                      "alias": "log"
                  }
                },
                {
                  "remove": {
                      "index": "log-00001",
                      "alias": "log"
                  }
                }
              ]
            }
          }
        ]
      }
    ],
    "ism_template": {
      "index_patterns": ["log*"],
      "priority": 100
    }
  }
}
'

2.2 This will create an Illegal argument exception with the error: "Alias action can only work on its applied index so don't accept index/indices parameter."

3. Fail the case if a user tries to remove index using alias action.
3.1 Create the following policy:

curl -X PUT "localhost:9200/_plugins/_ism/policies/remove_index_policy?pretty" -H 'Content-Type: application/json' -d'
{
  "policy": {
    "description": "Example remove index policy.",
    "default_state": "alias",
    "states": [
      {
        "name": "alias",
        "actions": [
          {
            "alias": {
              "actions": [
                {
                  "remove_index": {
                      "index": "log"
                  }
                }
              ]
            }
          }
        ]
      }
    ],
    "ism_template": {
      "index_patterns": ["log*"],
      "priority": 100
    }
  }
}
'

3.2 This will create an Illegal argument exception with the error: "Only ADD and REMOVE actions are allowed."


-----------------------

NOTE: Use the following command to make the cluster green:

curl -X PUT "localhost:9200/log-000001/_settings" -H 'Content-Type: application/json' -d'
{
    "index" : {
        "number_of_replicas" : 0
    }
}
'