File-based logging in Spring Boot

Introduction

File-based logging saves messages from your application into files. This helps you keep track of what happened and find problems later.

You want to keep a record of application errors for troubleshooting.

You need to monitor application activity over time.

You want to share logs with your team for debugging.

You want to keep logs even after the application stops.

You want to analyze logs with external tools.

Syntax

Spring Boot

logging:
  file:
    name: logs/app.log
  level:
    root: INFO

This example is for application.yml in Spring Boot.

logging.file.name sets the log file path.

Examples

This is the same setup but in application.properties format.

Spring Boot

logging.file.name=logs/app.log
logging.level.root=INFO

Logs saved to /var/log/myapp.log with debug level for more details.

Spring Boot

logging:
  file:
    name: /var/log/myapp.log
  level:
    root: DEBUG

Custom log message format with date and message.

Spring Boot

logging:
  file:
    name: logs/app.log
  pattern:
    file: "%d{yyyy-MM-dd HH:mm:ss} - %msg%n"

Sample Program

This configuration saves logs to logs/app.log with info level messages and above.

Spring Boot

logging:
  file:
    name: logs/app.log
  level:
    root: INFO

Important Notes

Make sure the folder for logs exists or your app can create it.

Log files can grow large; consider log rotation tools for long-term use.

You can change log levels to control how much detail is saved.

Summary

File-based logging saves app messages to a file for later review.

Configure file path and log level in application.yml or application.properties.

Useful for debugging, monitoring, and sharing logs.