15_LogManagement_Docker

Managing Log Files

1) Standard Logging: JSON Outputting

• Docker Engine keeps a track of the Standard Error and Standard Output Stream and maintains a log of the same which can be made available to the client using the following command:

$ docker logs [container name or ID]

2) SYSLog

By default, the Docker logs are outputting using the json-file logger meaning the output stored in a JSON file on the host. This can result in large files filling the disk. As a result, you can change the log driver to move to a different destination

Syslog: Syslog is a widely used standard for message logging. It permits separation of the software that generates messages, the system that stores them, and the software that reports and analyses them.

docker run --log-driver=syslog [Image name]

• Checking logs of Docker containers whose logs are synced with Syslog driver result in FATA[0000] error. System logs can only be accessed by using the Syslog stream.

3) Disable Logging

We can disable logging for some containers that are not very critical but very verbose.

$ docker run --log-driver=none [image name]

Modifying docker inspect command using Golang to check the Logging Method

docker inspect --format '{{ .HostConfig.LogConfig }}' [container name or container ID]

References

KataCoda Scenarios