---
title: key
description: 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 in your elasticsearch.yml...
url: https://www.elastic.co/elastic/docs-builder/docs/3016/reference/elasticsearch/curator/fe_key
products:
  - Elasticsearch
  - Elasticsearch Curator
---

# key
<note>
  This setting is required when using the [allocated filtertype](https://www.elastic.co/elastic/docs-builder/docs/3016/reference/elasticsearch/curator/filtertype_allocated).
</note>

```yaml
- filtertype: allocated
  key: ...
  value: ...
  allocation_type:
  exclude: True
```

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
```sh
node.tag: myvalue
```

in your `elasticsearch.yml` file for one or more of your nodes.  To match allocation in this case, set key to `tag`.
These special attributes are also supported:

| attribute     | description                                                  |
|---------------|--------------------------------------------------------------|
| `_name`       | Match nodes by node name                                     |
| `_host_ip`    | Match nodes by host IP address (IP associated with hostname) |
| `_publish_ip` | Match nodes by publish IP address                            |
| `_ip`         | Match either `_host_ip` or `_publish_ip`                     |
| `_host`       | Match nodes by hostname                                      |

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