--- description: Configure logging driver. keywords: docker, logging, driver redirect_from: - /engine/reference/logging/overview/ - /engine/reference/logging/ - /engine/admin/reference/logging/ title: Configure logging drivers --- Docker includes multiple logging mechanisms to help you [get information from running containers and services](/engine/admin/logging/view_container_logs.md). These mechanisms are called logging drivers. Each Docker daemon has a default logging driver, which each container uses unless you configure it to use a different logging driver. In addition to using the logging drivers included with Docker, you can also implement and use [logging driver plugins](/engine/admin/logging/plugins.md). Logging driver plugins are available in Docker 17.05 and higher. ## Configure the default logging driver To configure the Docker daemon to default to a specific logging driver, set the value of `log-driver` to the name of the logging driver in the `daemon.json` file, which is located in `/etc/docker/` on Linux hosts or `C:\ProgramData\docker\config\` on Windows server hosts. The default logging driver is `json-file`. The following example explicitly sets the default logging driver to `syslog`: ```json { "log-driver": "syslog" } ``` If the logging driver has configurable options, you can set them in the `daemon.json` file as a JSON array with the key `log-opts`. The following example sets two configurable options on the `json-file` logging driver: ```json { "log-driver": "json-file", "log-opts": { "labels": "production_status", "env": "os,customer" } } ``` If you do not specify a logging driver, the default is `json-file`. Thus, the default output for commands such as `docker inspect ` is JSON. To find the current default logging driver for the Docker daemon, run `docker info` and search for `Logging Driver`. You can use the following command on Linux, macOS, or PowerShell on Windows: ```bash $ docker info | grep 'Logging Driver' Logging Driver: json-file ``` ## Configure the logging driver for a container When you start a container, you can configure it to use a different logging driver than the Docker daemon's default, using the `--log-driver` flag. If the logging driver has configurable options, you can set them using one or more instances of the `--log-opt =` flag. Even if the container uses the default logging driver, it can use different configurable options. The following example starts an Alpine container with the `none` logging driver. ```bash $ docker run -it --log-driver none alpine ash ``` To find the current logging driver for a running container, if the daemon is using the `json-file` logging driver, run the following `docker inspect` command, substituting the container name or ID for ``: ```bash {% raw %} $ docker inspect -f '{{.HostConfig.LogConfig.Type}}' json-file {% endraw %} ``` ## Configure the delivery mode of log messages from container to log driver Docker provides two modes for delivering messages from the container to the log driver: * (default) direct, blocking delivery from container to driver * non-blocking delivery that stores log messages in an intermediate per-container ring buffer for consumption by driver The `non-blocking` message delivery mode prevents applications from blocking due to logging back pressure. Applications are likely to fail in unexpected ways when STDERR or STDOUT streams block. > **WARNING**: When the buffer is full and a new message is enqueued, the oldest message in memory is dropped. Dropping messages is often preferred to blocking the log-writing process of an application. {: .warning} The `mode` log option controls whether to use the `blocking` (default) or `non-blocking` message delivery. The `max-buffer-size` log option controls the size of the ring buffer used for intermediate message storage when `mode` is set to `non-blocking`. `max-buffer-size` defaults to 1 megabyte. The following example starts an Alpine container with log output in non-blocking mode and a 4 megabyte buffer: ```bash $ docker run -it --log-opt mode=non-blocking --log-opt max-buffer-size=4m alpine ping 127.0.0.1 ``` ### Use environment variables or labels with logging drivers Some logging drivers add the value of a container's `--env|-e` or `--label` flags to the container's logs. This example starts a container using the Docker daemon's default logging driver (let's assume `json-file`) but sets the environment variable `os=ubuntu`. ```bash $ docker run -dit --label production_status=testing -e os=ubuntu alpine sh ``` If the logging driver supports it, this adds additional fields to the logging output. The following output is generated by the `json-file` logging driver: ```json "attrs":{"production_status":"testing","os":"ubuntu"} ``` ## Supported logging drivers The following logging drivers are supported. See the link to each driver's documentation for its configurable options, if applicable. If you are using [logging driver plugins](/engine/admin/logging/plugins.md), you may see more options. | Driver | Description | |:------------------------------|:--------------------------------------------------------------------------------------------------------------| | `none` | No logs are available for the container and `docker logs` does not return any output. | | [`json-file`](json-file.md) | The logs are formatted as JSON. The default logging driver for Docker. | | [`syslog`](syslog.md) | Writes logging messages to the `syslog` facility. The `syslog` daemon must be running on the host machine. | | [`journald`](journald.md) | Writes log messages to `journald`. The `journald` daemon must be running on the host machine. | | [`gelf`](gelf.md) | Writes log messages to a Graylog Extended Log Format (GELF) endpoint such as Graylog or Logstash. | | [`fluentd`](fluentd.md) | Writes log messages to `fluentd` (forward input). The `fluentd` daemon must be running on the host machine. | | [`awslogs`](awslogs.md) | Writes log messages to Amazon CloudWatch Logs. | | [`splunk`](splunk.md) | Writes log messages to `splunk` using the HTTP Event Collector. | | [`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. | ## Limitations of logging drivers The `docker logs` command is not available for drivers other than `json-file` and `journald`.