Log Rotation for Nginx Running on Docker

🎯 Why Log Rotation Matters

Web applications, especially under heavy traffic, produce a large amount of log data through Nginx when it works as a reverse proxy. Over time these logs can grow significantly. If log files are not rotated and managed properly, disk space can fill up, performance can degrade, and services can be interrupted.

In Docker containers, this problem becomes more complex because containers are often short-lived and their internal logs may be isolated from the host system.

🧱 Understanding the Basic Architecture

Applications running inside Docker containers usually write logs either to the filesystem or directly to standard output.

1. File-Based Logging

access_log /var/log/nginx/access.log;
error_log /var/log/nginx/error.log;

This method stores logs directly on the filesystem. If the files stay inside the container, the host cannot manage them easily. A volume mount is required.

2. Stdout/Stderr Forwarding

access_log /dev/stdout;
error_log /dev/stderr;

With this approach, Docker receives the logs and rotation can be handled by Docker’s log driver.

🔧 Method 1: File-Based Logging + Host Logrotate

Mount Nginx logs to the host:

services:
  nginx:
    image: nginx:stable
    volumes:
      - ./logs:/var/log/nginx

Create a logrotate rule:

sudo nano /etc/logrotate.d/nginx-docker

/home/kullanici/nginx-logs/*.log {
    daily
    missingok
    rotate 7
    compress
    delaycompress
    notifempty
    create 0640 root adm
    sharedscripts
    postrotate
        docker exec nginx-container-name nginx -s reopen
    endscript
}

nginx -s reopen is required because Nginx can continue writing to the old file handle after logrotate renames the file.

docker exec nginx-container-name nginx -s reopen

Alternative:

kill -USR1 $(cat /var/run/nginx.pid)

🛠️ Method 2: Docker Log Driver

services:
  nginx:
    image: nginx
    logging:
      driver: "json-file"
      options:
        max-size: "10m"
        max-file: "5"

This rotates log files after 10 MB and keeps up to 5 files.

Docker log path:

/var/lib/docker/containers/<container-id>/<container-id>-json.log

🧪 Testing and Validation

docker exec nginx-container-name bash -c "for i in {1..10000}; do echo \"$(date) log test\" >> /var/log/nginx/access.log; done"
sudo logrotate -f /etc/logrotate.d/nginx-docker

Verify that a new log file is created and Nginx continues writing to it.

🧩 Common Issues

🔚 Conclusion

Log management for Nginx running in Docker is critical for system stability. Whether using traditional logrotate or Docker’s json-file log driver, rotation should be configured intentionally.

Created: 2025-05-2025