How to resolve the issue of disappearing logs after restarting Docker?

When Docker restarts, the logs of the container may be lost because Docker by default only retains the most recent output logs of the container and does not save previous log entries.

To address this issue, we can consider the following methods:

1. To save logs using the docker logs command, you can specify the log driver and set options for saving logs when starting a container. For example, using –log-driver=json-file will save logs as JSON files, and using –log-opt max-size=10m will set the maximum file size for each log to 10MB. This way, even if the container restarts, previous logs will still be saved in these files.
2. Utilize third-party logging management tools such as ELK Stack, Graylog, or Fluentd to manage and store Docker container logs. These tools offer advanced log processing and management features, allowing for easy storage and search of container logs.
3. Write logs to a file in a container: You can redirect log output to a file instead of standard output within a container. This way, even if the container restarts, the log file will still be preserved. You can add a command in the container’s startup script to redirect logs to a file, for example, docker run … > /var/log/myapp.log.
4. Regularly backup log files: You can schedule a task to periodically backup the container’s log files to another location, such as a remote server or storage device. This way, even if the container restarts and log files are lost, previous logs can be recovered from the backup.

In summary, to address the issue of logs disappearing after restarting Docker, you can use the docker logs command to save logs, utilize a third-party logging tool, write logs to a file, or regularly back up log files. Choose a suitable method based on specific needs and circumstances to save and manage container logs.