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This article is to share with you about how Docker supports a variety of log programs, the editor thinks it is very practical, so I share it with you to learn. I hope you can get something after reading this article.

Sending container logs to STDOUT and STDERR is the default logging behavior for Docker. In fact, Docker provides a variety of logging mechanisms to help users extract log information from the running container. These mechanisms are called logging driver.

The default logging driver for Docker is json-file.

# docker info | grep 'Logging Driver'Logging Driver: json-file

This default logging driver is used if the container is not specifically specified at startup.

Json-file saves the container log in the json file, and Docker is responsible for formatting its contents and outputting them to STDOUT and STDERR.

We can find this file in the container directory of Host, and the path is / var/lib/docker/containers//-json.log

For example, we can look at the log file in the previous httpd container json format.

You can see five log records.

In addition to json-file,Docker, a variety of logging driver is also supported. File https://docs.docker.com/engine/admin/logging/overview/#supported-logging-drivers

None is the disable container logging feature.

Syslog and journald are two log management services on Linux.

Awslogs, splunk, and gcplogs are third-party log hosting services.

Gelf and fluentd are two open source log management solutions, which we will discuss later.

The logging driver to be used can be specified by-- log-driver when the container is started. If you want to set the default logging driver for Docker, you need to modify the startup script of Docker daemon and specify the-- log-driver parameter, such as:

ExecStart=/usr/bin/dockerd-H fd://-- log-driver=syslog-- log-opt.

Each logging driver has its own log-opt.

This is how Docker supports a variety of log solutions, and the editor believes that there are some knowledge points that we may see or use in our daily work. I hope you can learn more from this article. For more details, please follow the industry information channel.

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