110 lines
3.8 KiB
Markdown
110 lines
3.8 KiB
Markdown
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<!--[metadata]>
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+++
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title = "Fluentd logging driver"
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description = "Describes how to use the fluentd logging driver."
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keywords = ["Fluentd, docker, logging, driver"]
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[menu.main]
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parent = "smn_logging"
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+++
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<![end-metadata]-->
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# Fluentd logging driver
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The `fluentd` logging driver sends container logs to the
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[Fluentd](http://www.fluentd.org/) collector as structured log data. Then, users
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can use any of the [various output plugins of
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Fluentd](http://www.fluentd.org/plugins) to write these logs to various
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destinations.
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In addition to the log message itself, the `fluentd` log
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driver sends the following metadata in the structured log message:
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| Field | Description |
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-------------------|-------------------------------------|
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| `container_id` | The full 64-character container ID. |
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| `container_name` | The container name at the time it was started. If you use `docker rename` to rename a container, the new name is not reflected in the journal entries. |
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| `source` | `stdout` or `stderr` |
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## Usage
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Configure the default logging driver by passing the
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`--log-driver` option to the Docker daemon:
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docker --log-driver=fluentd
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To set the logging driver for a specific container, pass the
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`--log-driver` option to `docker run`:
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docker run --log-driver=fluentd ...
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Before using this logging driver, launch a Fluentd daemon. The logging driver
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connects to this daemon through `localhost:24224` by default. Use the
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`fluentd-address` option to connect to a different address.
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docker run --log-driver=fluentd --log-opt fluentd-address=myhost.local:24224
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If container cannot connect to the Fluentd daemon, the container stops
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immediately.
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## Options
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Users can use the `--log-opt NAME=VALUE` flag to specify additional Fluentd logging driver options.
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### fluentd-address
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By default, the logging driver connects to `localhost:24224`. Supply the
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`fluentd-address` option to connect to a different address.
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docker run --log-driver=fluentd --log-opt fluentd-address=myhost.local:24224
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### fluentd-tag
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Every Fluentd's event has a tag that indicates where the log comes from. By
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default, the driver uses the `docker.{{.ID}}` tag. Use the `fluentd-tag` option
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to change this behavior.
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When specifying a `fluentd-tag` value, you can use the following markup tags:
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- `{{.ID}}`: short container id (12 characters)
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- `{{.FullID}}`: full container id
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- `{{.Name}}`: container name
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## Note regarding container names
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At startup time, the system sets the `container_name` field and `{{.Name}}`
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in the tags to their values at startup. If you use `docker rename` to rename a
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container, the new name is not be reflected in `fluentd` messages. Instead,
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these messages continue to use the original container name.
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## Fluentd daemon management with Docker
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About `Fluentd` itself, see [the project webpage](http://www.fluentd.org)
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and [its documents](http://docs.fluentd.org/).
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To use this logging driver, start the `fluentd` daemon on a host. We recommend
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that you use [the Fluentd docker
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image](https://registry.hub.docker.com/u/fluent/fluentd/). This image is
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especially useful if you want to aggregate multiple container logs on a each
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host then, later, transfer the logs to another Fluentd node to create an
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aggregate store.
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### Testing container loggers
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1. Write a configuration file (`test.conf`) to dump input logs:
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<source>
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@type forward
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</source>
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<match docker.**>
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@type stdout
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</match>
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2. Launch Fluentd container with this configuration file:
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$ docker run -it -p 24224:24224 -v /path/to/conf/test.conf:/fluentd/etc -e FLUENTD_CONF=test.conf fluent/fluentd:latest
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3. Start one or more containers with the `fluentd` logging driver:
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$ docker run --log-driver=fluentd your/application
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