How to Identify, Clean, and Limit Docker Container Logs to Prevent Disk Space Exhaustion

Docker container logs can quickly fill the host's disk space, especially when using commands like docker logs -f container_name that generate large amounts of output.

2.1 Find Docker container logs – On Linux, logs are stored under /var/lib/docker/containers/<container_id>/. The following shell script docker_log_size.sh lists the size of each *-json.log file:

#!/bin/sh

echo "======== docker containers logs file size ========"
logs=$(find /var/lib/docker/containers/ -name *-json.log)

for log in $logs
do
  ls -lh $log
done
# chmod +x docker_log_size.sh
# ./docker_log_size.sh

2.2 Clean Docker container logs (temporary fix) – Deleting log files with rm -rf does not free space while the container is running because the file remains open. Truncate the log files instead:

#!/bin/sh

echo "======== start clean docker containers logs ========"

logs=$(find /var/lib/docker/containers/ -name *-json.log)

for log in $logs
do
  echo "clean logs : $log"
  cat /dev/null > $log
 done

echo "======== end clean docker containers logs ========"
# chmod +x clean_docker_log.sh
# ./clean_docker_log.sh

After truncation, the logs will grow again over time, so a permanent solution is needed.

2.3 Set Docker container log size limits (permanent fix) – Use the max-size option in docker‑compose to cap log file size per container, e.g., for an Nginx service:

nginx:
  image: nginx:1.12.1
  restart: always
  logging:
    driver: "json-file"
    options:
      max-size: "5g"

For a global setting, create or edit /etc/docker/daemon.json and add log-driver and log-opts:

{
  "log-driver":"json-file",
  "log-opts": {"max-size":"500m", "max-file":"3"}
}

Here max-size=500m limits each log file to 500 MB, and max-file=3 keeps three rotated log files (e.g., id.json, id1.json, id2.json).

After updating the daemon configuration, reload and restart Docker:

# systemctl daemon-reload
# systemctl restart docker