Merge pull request #6717 from cpuguy83/add_local_logger_docs

Add docs for `local` logging driver.
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paigehargrave 2018-12-28 13:48:38 -05:00 committed by GitHub
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@ -150,9 +150,12 @@ see more options.
| [`etwlogs`](etwlogs.md) | Writes log messages as Event Tracing for Windows (ETW) events. Only available on Windows platforms. |
| [`gcplogs`](gcplogs.md) | Writes log messages to Google Cloud Platform (GCP) Logging. |
| [`logentries`](logentries.md) | Writes log messages to Rapid7 Logentries. |
| [`local`](local.md) | Logs are stored in a custom format designed for minimal overhead. |
## Limitations of logging drivers
The `docker logs` command is not available for drivers other than `json-file`
and `journald`.
The `docker logs` command is only available on the following drivers:
- `json-file`
- `journald`
- `local`

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| `labels` | Applies when starting the Docker daemon. A comma-separated list of logging-related labels this daemon accepts. Used for advanced [log tag options](log_tags.md). | `--log-opt labels=production_status,geo` |
| `env` | Applies when starting the Docker daemon. A comma-separated list of logging-related environment variables this daemon accepts. Used for advanced [log tag options](log_tags.md). | `--log-opt env=os,customer` |
| `env-regex` | Similar to and compatible with `env`. A regular expression to match logging-related environment variables. Used for advanced [log tag options](log_tags.md). | `--log-opt env-regex=^(os|customer).` |
| `compress` | Toggles compression for rotated logs. Default is disabled | `--log-opt compress=true` |
### Examples

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---
description: Describes how to use the local logging driver.
keywords: local, docker, logging, driver
redirect_from:
- /engine/reference/logging/local/
- /engine/admin/logging/local/
title: Local File logging driver
---
The `local` logging driver captures output from container's stdout/stderr and
writes them to an internal storage that is optimized for performance and disk
use.
By default the `local` driver preserves 100MB of log messages per container and
uses automatic compression to reduce the size on disk.
> *Note*: the `local` logging driver currently uses file-based storage. The
> file-format and storage mechanism are designed to be exclusively accessed by
> the Docker daemon, and should not be used by external tools as the
> implementation may change in future releases.
## Usage
To use the `local` driver as the default logging driver, set the `log-driver`
and `log-opt` keys to appropriate values in the `daemon.json` file, which is
located in `/etc/docker/` on Linux hosts or
`C:\ProgramData\docker\config\daemon.json` on Windows Server. For more about
configuring Docker using `daemon.json`, see
[daemon.json](/engine/reference/commandline/dockerd.md#daemon-configuration-file).
The following example sets the log driver to `local` and sets the `max-size`
option.
```json
{
"log-driver": "local",
"log-opts": {
"max-size": "10m"
}
}
```
Restart Docker for the changes to take effect for newly created containers. Existing containers do not use the new logging configuration.
You can set the logging driver for a specific container by using the
`--log-driver` flag to `docker container create` or `docker run`:
```bash
$ docker run \
--log-driver local --log-opt max-size=10m \
alpine echo hello world
```
### Options
The `local` logging driver supports the following logging options:
| Option | Description | Example value |
|:------------|:--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|:-----------------------------------------|
| `max-size` | The maximum size of the log before it is rolled. A positive integer plus a modifier representing the unit of measure (`k`, `m`, or `g`). Defaults to 20MB. | `--log-opt max-size=10m` |
| `max-file` | The maximum number of log files that can be present. If rolling the logs creates excess files, the oldest file is removed. **Only effective when `max-size` is also set.** A positive integer. Defaults to 5. | `--log-opt max-file=3` |
| `compress` | Toggle compression of rotated log files. Enabled by default. | `--log-opt compress=false` |
### Examples
This example starts an `alpine` container which can have a maximum of 3 log
files no larger than 10 megabytes each.
```bash
$ docker run -it --log-opt max-size=10m --log-opt max-file=3 alpine ash
```