Index lifecycle policy - warm phase not readonly

Hello,

I am confused about an index I created. I have a template, which uses a lifecycle policy as follows:

{
  "policy": {
    "phases": {
      "hot": {
        "actions": {
          "set_priority": {
            "priority": null
          }
        }
      },
      "warm": {
        "min_age": "1d",
        "actions": {
          "set_priority": {
            "priority": null
          }
        }
      }
    }
  }
}

The index status I get using /_ilm/explain is as follows:

{
  "indices" : {
    "<my index>" : {
      "index" : "<my index>",
      "managed" : true,
      "policy" : "<my policy name>",
      "lifecycle_date_millis" : <some date>,
      "age" : "1.89d",
      "phase" : "warm",
      "phase_time_millis" : <some date>,
      "action" : "complete",
      "action_time_millis" : <some date>,
      "step" : "complete",
      "step_time_millis" : <some date>,
      "phase_execution" : {
        "policy" : "<my policy name>",
        "phase_definition" : {
          "min_age" : "1d",
          "actions" : { }
        },
        "version" : <version number>,
        "modified_date_in_millis" : <some date>
      }
    }
  }
}

Clearly, my index, being more than 1 day old, is currently in the warm phase. However, I am still able to insert documents into it.

Based on the documentation about ILM

  • Warm : The index is no longer being updated but is still being queried.

I thought "warm" meant readonly. Is that not the case? If it does not mean readonly, what does warm do?

Have you tried adding a read-only action to the warm phase?