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Logrotation for AccessLog

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Introduction

This post is about enabling log rotation for the Traefik access.log. Some information is sourced from this post, with additional insights by Aeoneros.

Warning: Log Rotation

Traefik will close and reopen its log files, assuming they’re configured, upon receiving a USR1 signal. This enables the logs to be rotated and processed by external programs like logrotate. However, this does not work on Windows due to the lack of USR signals.

The access.log requires a different setup compared to the standard Traefik logs. For more details, refer to this post. Below are the steps to manually create log rotation for the access.log.

Step 1: Configure the Path of the Access.log

In your Traefik static configuration file (e.g., traefik.toml), define the file path for the access.log. For example:

[accessLog]
  filePath = "/mnt/glustermount/data/traefik_data/access.log"

Refer to the official documentation here.

Step 2: Install Logrotate

Ensure the logrotate package is installed on your Debian-based system. Install it if necessary:

sudo apt update
sudo apt install logrotate

Step 3: Create a Logrotate File

Create a new configuration file for Traefik log rotation:

sudo nano /etc/logrotate.d/traefik

Step 4: Configure Logrotate

Paste the following content into the file:

/mnt/glustermount/data/traefik_data/access.log {
  compress
  create 0640 root root
  daily
  delaycompress
  missingok
  notifempty
  rotate 5
  postrotate
    # Send USR1 signal to reopen logs
    docker kill --signal=USR1 $(docker ps --filter "name=traefik_traefik" --format "{{.ID}}")
    # Pause to give Traefik time to process the signal
    sleep 5
    # Verify that Traefik is writing to the correct log file
    if [ -s /mnt/glustermount/data/traefik_data/access.log.1 ]; then
      # Restart service if still writing to the rotated file
      docker service update --force traefik_traefik
    fi
  endscript
}

Explanation:

  • The postrotate script first sends a USR1 signal to Traefik to reopen its log files.
  • If Traefik continues writing to the rotated file, it restarts the container using docker service update --force.
  • This ensures that logs are properly rotated and written to the correct file.

Step 5: Debugging Logrotate

Test your logrotate configuration in debug mode:

sudo logrotate -d /etc/logrotate.d/traefik

Step 6: Force Logrotate

Force log rotation to execute the script:

sudo logrotate -f /etc/logrotate.d/traefik

Step 7: Verify Log Rotation

Check if new files were created and if Traefik is writing to the correct log file:

ls -lh /mnt/glustermount/data/traefik_data/access.log*
tail -f /mnt/glustermount/data/traefik_data/access.log

Troubleshooting

If nothing is working, revert the changes by following these steps:

  1. Rename or delete the logrotate file:
sudo mv /etc/logrotate.d/traefik /etc/logrotate.d/traefik.bak
  1. Edit the logrotate status file to remove entries related to the access.log:
sudo nano /var/lib/logrotate/status
  1. Look for and remove entries related to /mnt/glustermount/data/traefik_data/access.log.

Reapply the steps once the issue is resolved.

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