# secondary\_file

![](https://1982584918-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F-LR7OsqPORtP86IQxs6E-694727794%2Fuploads%2Fgit-blob-81ab02b63579e64cfe861d734da2de3a69639854%2Ffile.png?alt=media)

The `out_secondary_file` Output plugin writes chunks to files. This plugin is similar to `out_file` but this is for `<secondary>` use-case.

NOTE: Do not use this plugin for the primary plugin.

`out_secondary_file` is included in Fluentd's core.

## Example Configuration

```
<match pattern>
  @type forward
  # ...
  <secondary>
    @type secondary_file
    directory /var/log/fluentd/error
  </secondary>
</match>
```

With this configuration, failed buffer chunks are saved into `/var/log/fluentd/error/dump.bin.N`, `N` is 0-origin incremental number.

Please see the [Configuration File](https://docs.fluentd.org/configuration/config-file) article for the basic structure and syntax of the configuration file.

## Plugin Helpers

No helpers.

## Parameters

[Common Parameters](https://docs.fluentd.org/configuration/plugin-common-parameters)

### `@type` (required)

The value must be `secondary_file`.

### `directory`

| type   | default            | version |
| ------ | ------------------ | ------- |
| string | required parameter | 1.0.0   |

The directory path of the output file. Received buffer chunks are saved in this directory.

```
<secondary>
  @type secondary_file
  directory /var/log/fluentd/error
</secondary>
```

### `basename`

| type   | default  | version |
| ------ | -------- | ------- |
| string | dump.bin | 1.0.0   |

The basename of the output file. You can use `${chunk_id}` placeholder to identify the original chunk.

```
<secondary>
  @type secondary_file
  directory /var/log/fluentd/error
  basename dump.${chunk_id}
</secondary>
```

The output path would be:

```
# 59c278456e74a22dc594b06a7d4247c4 is chunk id
/var/log/fluentd/error/dump.59c278456e74a22dc594b06a7d4247c4.0
```

### `append`

| type | default | version |
| ---- | ------- | ------- |
| bool | false   | 1.0.0   |

Determines that the received chunk is appended to an existing file or not. By default, it is not appended and each chunk is flushed to a different path:

```
# append false
dump.bin.0
dump.bin.1
dump.bin.2
...
dump.bin.N
```

This makes parallel file processing easy. But if you want to disable this behavior, you can disable it by setting `append true`:

```
# append true
dump.bin
```

### `compress`

| type | default | version |
| ---- | ------- | ------- |
| enum | text    | 1.0.0   |

Supported compress types: `text`, `gzip`

When `gzip` is specified, `.gz` is automatically added to the output file path as its suffix.

## How to resend secondary file

The secondary file can be resend by `fluent-cat` command.

Here is the example to resend `dump.bin.0` to `127.0.0.1:24224` using `fluent-cat`.

```
$ cat /path/to/dump.bin.0 | fluent-cat --format msgpack  --host 127.0.0.1 --port 24224 TAG
```

See [fluent-cat](https://docs.fluentd.org/deployment/command-line-option#fluent-cat) command line option about details.

If this article is incorrect or outdated, or omits critical information, please [let us know](https://github.com/fluent/fluentd-docs-gitbook/issues?state=open). [Fluentd](http://www.fluentd.org/) is an open-source project under [Cloud Native Computing Foundation (CNCF)](https://cncf.io/). All components are available under the Apache 2 License.