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Logging Configuration

Configure logging levels and module-specific logging for Watch Tower. The Watch Tower provides flexible logging configuration through the LOG_LEVEL environment variable. You can control both global and module-specific logging levels.

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Log levels

The following log levels are available, from most to least verbose:
  • TRACE - Most detailed logging
  • DEBUG - Debug information
  • INFO - Informational messages
  • WARN - Warning messages
  • ERROR - Error messages only

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Setting the log level

Set the LOG_LEVEL environment variable to control logging verbosity: 
LOG_LEVEL=INFO yarn cli run --config-path ./config.json

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Module-specific logging

You can override the log level for specific modules using comma-separated values: 
LOG_LEVEL=WARN,chainContext=INFO
This sets the global log level to WARN, but enables INFO level logging for the chainContext module.

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Multiple module overrides

Specify multiple module overrides separated by commas: 
LOG_LEVEL=WARN,chainContext=INFO,_placeOrder=TRACE
In this example:
  • Global log level: WARN
  • chainContext module: INFO
  • _placeOrder module: TRACE

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Regex patterns for logger names

Module names can be regex patterns, allowing fine-grained control over logging:

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Pattern matching examples

# Matches: chainContext:processBlock:100:30212964
# Matches: chainContext:processBlock:1:30212964
# Matches: chainContext:processBlock:5:30212964
LOG_LEVEL='chainContext:processBlock:(\d{1,3}):(\d*)$=DEBUG'
Use single quotes around the LOG_LEVEL value when using regex patterns to prevent shell interpretation of special characters.

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Complex logging configuration

Combine multiple techniques for precise control: 
LOG_LEVEL="WARN,commands=DEBUG,^checkForAndPlaceOrder=WARN,^chainContext=INFO,_checkForAndPlaceOrder:1:=INFO" yarn cli
This configuration:
  • Sets global log level to WARN
  • Enables DEBUG for commands module
  • Sets WARN for loggers starting with checkForAndPlaceOrder
  • Sets INFO for loggers starting with chainContext
  • Sets INFO for _checkForAndPlaceOrder:1: loggers

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Using with Docker

When running the Watch Tower in Docker, pass the LOG_LEVEL environment variable: 
docker run --rm -it \
  -e LOG_LEVEL=WARN \
  -v "$(pwd)/config.json:/config.json" \
  ghcr.io/cowprotocol/watch-tower:latest \
  run --config-path /config.json

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Using with environment files

Create a .env file for persistent configuration: 
LOG_LEVEL=WARN
Or with module-specific logging: 
LOG_LEVEL=WARN,chainContext=INFO,_placeOrder=TRACE
Then load it with Docker: 
docker run --rm -it \
  --env-file .env \
  -v "$(pwd)/config.json:/config.json" \
  ghcr.io/cowprotocol/watch-tower:latest \
  run --config-path /config.json

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Common logging patterns

LOG_LEVEL=WARN

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Tips

  • Start with WARN in production to reduce log volume
  • Use DEBUG or TRACE when troubleshooting specific issues
  • Module-specific logging helps debug particular components without flooding logs
  • Regex patterns are powerful but require careful escaping in shell commands
  • Remember to quote complex LOG_LEVEL values containing special characters
Last modified on March 4, 2026