This setting is optional when using the allocation action and required when using the cluster_routing action.

For the allocation action, the value of this setting should correspond to a node setting on one or more nodes in your cluster

For example, you might have set

node.tag: myvalue

in your elasticsearch.yml file for one or more of your nodes. To match allocation in this case, set value to myvalue. Additonally, if you used one of the special attribute names _ip, _name, _id, or _host for key, value can match the one of the node ip addresses, names, ids, or host names, respectively.

To remove a routing allocation, the value of this setting should be left empty, or the value setting not even included as an option.

For example, you might have set

PUT test/_settings
  "index.routing.allocation.exclude.size": "small"

to keep index test from allocating shards on nodes that have node.tag: small. To remove this shard routing allocation setting, you might use an action file similar to this:

      action: allocation
      description: ->
        Unset 'index.routing.allocation.exclude.size' for index 'test' by
        passing an empty value.
        key: size
        value: ...
        allocation_type: exclude
      - filtertype: pattern
        kind: regex
        value: '^test$'

For the cluster_routing action, the acceptable values for this setting depend on the value of routing_type.

action: cluster_routing
description: "Apply routing rules to the entire cluster"
  routing_type: ...
  value: ...
  setting: enable
  wait_for_completion: True
  max_wait: 300
  wait_interval: 10

Acceptable values when routing_type is either allocation or rebalance are all, primaries, and none (string, not NoneType).

If routing_type is allocation, this can also be new_primaries. If routing_type is rebalance, then the value can also be replicas.

There is no default value. This setting must be set by the user or an exception will be raised, and execution will halt.