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chore: tier 1 freshness: content/config/containers/logging/dual-logging.md 

Signed-off-by: David Karlsson <35727626+dvdksn@users.noreply.github.com>
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David Karlsson 2023-10-27 13:40:33 +02:00
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content/config/containers/logging/dual-logging.md
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@ -1,7 +1,9 @@
---
description: Learn how to read container logs locally when using a third party logging
description:
Learn how to read container logs locally when using a third party logging
solution.
keywords: docker, logging, driver, dual logging, dual-logging, cache, ring-buffer,
keywords:
docker, logging, driver, dual logging, dual-logging, cache, ring-buffer,
configuration
title: Use docker logs with remote logging drivers
---
@ -37,7 +39,7 @@ section to disable this feature.
## Prerequisites
No configuration changes are needed to use dual logging. Docker Engine 20.10 and
up automatically enable dual logging if the configured logging driver does not
up automatically enable dual logging if the configured logging driver doesn't
support reading logs.
The following examples show the result of running a `docker logs` command with
@ -78,7 +80,7 @@ logs locally:
### With dual logging capability
With the dual logging cache enabled, the `docker logs` command can be used to
read logs, even if the logging driver does not support reading logs. The following
read logs, even if the logging driver doesn't support reading logs. The following
example shows a daemon configuration that uses the `splunk` remote logging driver
as a default, with dual logging caching enabled:
@ -120,7 +122,6 @@ as a default, with dual logging caching enabled:
> the dual logging capability became available. For these drivers, Logs can be
> read using `docker logs` in both scenarios.
### Configuration options
The "dual logging" cache accepts the same configuration options as the
@ -132,9 +133,8 @@ By default, the cache has log-file rotation enabled, and is limited to a maximum
of 5 files of 20MB each (before compression) per container. Use the configuration
options described below to customize these defaults.
| Option | Default | Description |
|:-----------------|:----------|:--------------------------------------------------------------------------------------------------------------------------------------------------|
| :--------------- | :-------- | :------------------------------------------------------------------------------------------------------------------------------------------------ |
| `cache-disabled` | `"false"` | Disable local caching. Boolean value passed as a string (`true`, `1`, `0`, or `false`). |
| `cache-max-size` | `"20m"` | The maximum size of the cache before it is rotated. A positive integer plus a modifier representing the unit of measure (`k`, `m`, or `g`). |
| `cache-max-file` | `"5"` | The maximum number of cache files that can be present. If rotating the logs creates excess files, the oldest file is removed. A positive integer. |
@ -150,7 +150,7 @@ through a remote logging system, and if there is no need to read logs through
Caching can be disabled for individual containers or by default for new containers,
when using the [daemon configuration file](/engine/reference/commandline/dockerd/#daemon-configuration-file).
The following example uses the daemon configuration file to use the ["splunk'](splunk.md)
The following example uses the daemon configuration file to use the [`splunk`](splunk.md)
logging driver as a default, with caching disabled:
```console
@ -167,16 +167,16 @@ $ cat /etc/docker/daemon.json
> **Note**
>
> For logging drivers that support reading logs, such as the `local`, `json-file`
> and `journald` drivers, dual logging is not used, and disabling the option has
> and `journald` drivers, dual logging isn't used, and disabling the option has
> no effect.
## Limitations
- If a container using a logging driver or plugin that sends logs remotely
suddenly has a "network" issue, no ‘write’ to the local cache occurs.
has a network issue, no `write` to the local cache occurs.
- If a write to `logdriver` fails for any reason (file system full, write
permissions removed), the cache write fails and is logged in the daemon log.
The log entry to the cache is not retried.
The log entry to the cache isn't retried.
- Some logs might be lost from the cache in the default configuration because a
ring buffer is used to prevent blocking the stdio of the container in case of
slow file writes. An admin must repair these while the daemon is shut down.