Traefik Logs

Traefik is a powerful reverse proxy that provides detailed logging capabilities. This guide explains how to effectively monitor and manage Traefik logs in your Docker environment.

Log File Location and Configuration

Traefik maintains two separate log files:

1. traefik.log - Contains general Traefik operational logs (errors and warnings)
2. access.log - Contains access logs for requests handled by Traefik

These files are located in:

/home/user/docker/logs/hostname/traefik/

The logging configuration is defined in the Traefik Docker Compose file through CLI arguments:

- --log=true
- --log.filePath=/logs/traefik.log
- --log.level=DEBUG # (Default: error) DEBUG, INFO, WARN, ERROR, FATAL, PANIC
- --accessLog=true
- --accessLog.filePath=/logs/access.log
- --accessLog.bufferingSize=100 # Configuring a buffer of 100 lines
- --accessLog.filters.statusCodes=204-299,400-499,500-599

Why File-Based Logging?

Traefik is configured to write logs to files instead of standard output for several key benefits:

1. Advanced Filtering:

   • Access logs can be filtered by status codes
   • Helps reduce noise and focus on relevant events

2. Log Persistence:

   • Logs persist between container restarts
   • Maintains historical data for troubleshooting

3. Integration Capabilities:

   • Easier integration with log management systems
   • Ability pass the logs to CrowdSec for real-time threat detection
   • Compatible with log rotation tools

Viewing Traefik Logs

⚠️ Important Warning

The commands docker compose logs traefik or docker logs traefik will show empty results. This is because Traefik is configured to write logs directly to files instead of standard output.

Standard Commands

To view Traefik logs in real-time:

# View Traefik operational logs
tail -f /home/user/docker/logs/hostname/traefik/traefik.log

# View access logs
tail -f /home/user/docker/logs/hostname/traefik/access.log

Using Bash Aliases

If you're using Anand's bash aliases, you can use the simplified command:

traefiklogs

Viewing Traefik Logs in Dozzle

If you are interested in viewing the logs in a more user-friendly way, you can use Dozzle. To pass Traefik logs to Dozzle, you can setup Traefik Error Logs and Traefik Access Logs apps from Deployrr Apps menu.

Log Levels

Traefik supports the following log levels (in order of verbosity):

Best Practices for Log Levels

1. During Setup/Troubleshooting:

   • Use DEBUG level for maximum visibility
   • Helps identify configuration issues and certificate problems

2. Production Environment:

   • Switch to INFO or WARN level
   • Reduces log volume while maintaining important information

To change the log level, modify the --log.level argument in your Traefik Docker Compose file:

--log.level=INFO  # Change from DEBUG to INFO after setup

Tips for Log Management

1. Initial Setup:

   • Keep log level at DEBUG
   • Monitor both traefik.log and access.log
   • Pay attention to LetsEncrypt certificate-related messages

2. Access Log Optimization:

   • Adjust status code filters to reduce noise:
     Copy

     --accessLog.filters.statusCodes=204-299,400-499,500-599

   • This captures successful responses, client errors, and server errors

3. Log Buffering:

   • Remember logs are buffered (100 lines) before disk write
   • Expect slight delay in seeing latest entries
   • Increase or decrease buffer size based on needs:
     Copy

     --accessLog.bufferingSize=100  # Adjust as needed

4. Log Rotation:

   • Implement log rotation to manage disk space
   • Consider using external log management solutions for long-term storage

Common Troubleshooting Scenarios

1. Empty Docker Logs:

   • If docker logs traefik shows nothing, this is normal
   • Use file-based log viewing commands instead

2. Missing Log Files:

   • Ensure proper volume mapping in Docker Compose
   • Check directory permissions
   • Verify log paths in Traefik configuration

3. High Log Volume:

   • Adjust log level to reduce verbosity
   • Fine-tune access log filters
   • Consider implementing log rotation