How Do I Update Index Lifecycle Policies for an Elasticsearch Cluster of CSS?

The lifecycle of Elasticsearch clusters is implemented using the Index State Management (ISM) of Open Distro. For details about how to configure policies related to the ISM template, see the Open Distro documentation.

1. When a policy is created, the system writes a record to the .opendistro-ism-config index. In the record, _id is the policy name, and the content is the policy definition.
   Figure 1 Writing a data record
   
2. After a policy is bound to an index, the system writes another record to the .opendistro-ism-config index. The following figure shows the initial status of a record.
   Figure 2 Initial data status
   
3. Run the explain command. Only a policy ID will be returned.

   GET _opendistro/_ism/explain/data2 
   {
     "data2" : {
       "index.opendistro.index_state_management.policy_id" : "policy1"
     }
   }

   Open Distro will execute an initialization process to fill the policy content in the record. The following figure shows the initialized data.

   Figure 3 Initialized data
   

   After the initialization, min_index_age in the policy will be copied.

   

   The initialized index uses a copy of this policy. The policy update will not take effect on the index.

4. After the policy is modified, call the change_policy API to update the policy.

   POST _opendistro/_ism/change_policy/data1
   {
     "policy_id": "policy1"
   }