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2nd chunk of `content/manuals/engine/logging/drivers/fluentd.md`
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`fluentd-address` option.

```json
{
  "log-driver": "fluentd",
  "log-opts": {
    "fluentd-address": "fluentdhost:24224"
  }
}
```

Restart Docker for the changes to take effect.

> [!NOTE]
>
> `log-opts` configuration options in the `daemon.json` configuration file must
> be provided as strings. Boolean and numeric values (such as the value for
> `fluentd-async` or `fluentd-max-retries`) must therefore be enclosed
> in quotes (`"`).

To set the logging driver for a specific container, pass the
`--log-driver` option to `docker run`:

```console
$ docker run --log-driver=fluentd ...
```

Before using this logging driver, launch a Fluentd daemon. The logging driver
connects to this daemon through `localhost:24224` by default. Use the
`fluentd-address` option to connect to a different address.

```console
$ docker run --log-driver=fluentd --log-opt fluentd-address=fluentdhost:24224
```

If container cannot connect to the Fluentd daemon, the container stops
immediately unless the `fluentd-async` option is used.

## Options

Users can use the `--log-opt NAME=VALUE` flag to specify additional Fluentd logging driver options.

### fluentd-address

By default, the logging driver connects to `localhost:24224`. Supply the
`fluentd-address` option to connect to a different address. `tcp`(default) and `unix` sockets are supported.

```console
$ docker run --log-driver=fluentd --log-opt fluentd-address=fluentdhost:24224
$ docker run --log-driver=fluentd --log-opt fluentd-address=tcp://fluentdhost:24224
$ docker run --log-driver=fluentd --log-opt fluentd-address=unix:///path/to/fluentd.sock
```

Two of the above specify the same address, because `tcp` is default.

### tag

By default, Docker uses the first 12 characters of the container ID to tag log messages.
Refer to the [log tag option documentation](log_tags.md) for customizing
the log tag format.

### labels, labels-regex, env, and env-regex

The `labels` and `env` options each take a comma-separated list of keys. If
there is collision between `label` and `env` keys, the value of the `env` takes
precedence. Both options add additional fields to the extra attributes of a
logging message.

The `env-regex` and `labels-regex` options are similar to and compatible with
respectively `env` and `labels`. Their values are regular expressions to match
Title: Fluentd Logging Driver Options
Summary
This section details the options available for configuring the Fluentd logging driver using the `--log-opt` flag. Key options include `fluentd-address` (to specify the Fluentd daemon address, defaulting to localhost:24224, supporting TCP and Unix sockets) and `tag` (for customizing log message tags, defaulting to the first 12 characters of the container ID). Additionally, the `labels`, `labels-regex`, `env`, and `env-regex` options can be used to add container labels and environment variables as extra attributes to the log messages, with `env` values taking precedence in case of key collisions. The `labels-regex` and `env-regex` options allow using regular expressions to match label and environment variable keys.