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Log Overflow

Log overflow occurs when container or application logs grow without bound, filling the host disk and causing the server and all containers to fail when the filesystem reaches 100% capacity.
DockerLoggingDisk SpaceLog RotationDevOps

Docker stores container logs in JSON files on the host at /var/lib/docker/containers/CONTAINER_ID/CONTAINER_ID-json.log. Without log rotation configured, verbose containers (web servers, databases) can fill the host disk within days or weeks.

When the host disk hits 100%, writes fail silently across all containers. The symptoms are non-obvious: cron jobs appear to run but write nothing, application errors increase, containers restart unexpectedly. The root cause — a full disk — is often discovered late.

Docker Log Rotation Options

The json-file logging driver (default) supports max-size and max-file options. Setting max-size: "10m" and max-file: "3" keeps at most 30MB of logs per container. This can be set globally in /etc/docker/daemon.json or per-service in docker-compose.yml under the logging key.

Checking Disk Usage

Run docker system df to see Docker's total disk usage. Run du -sh /var/lib/docker/containers/*/ to see per-container log sizes. A single misbehaving container can account for gigabytes of logs.

Related Tools

Docker Auditor →

Fix Guides

Docker log overflow fix

Frequently Asked Questions

How do I prevent Docker log files from filling my disk?
Set log rotation in /etc/docker/daemon.json: {"log-driver": "json-file", "log-opts": {"max-size": "10m", "max-file": "3"}}. This applies to all containers globally. Or set per-service in docker-compose.yml under the logging: key.
How do I clear existing Docker logs without deleting containers?
Truncate the log file: sudo truncate -s 0 /var/lib/docker/containers/CONTAINER_ID/CONTAINER_ID-json.log. Or run docker system prune to remove stopped containers and their logs. Running containers' logs can only be truncated, not deleted.
What is the best Docker logging driver for production?
For self-hosted setups with disk space concerns: json-file with rotation limits is simplest. For centralized log collection: loki (with Grafana Loki) or syslog. For AWS deployments: awslogs. Avoid none — it discards all logs, making debugging impossible.

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