File-based logging in Spring Boot - Practice Problems & Coding Challenges

Challenge - 5 Problems

💻 Command Output

intermediate

Log file creation with default Spring Boot logging

You run a Spring Boot application without any custom logging configuration. Which file will be created by default to store logs?

A No log file is created by default; logs go to console only

B application.log in the current directory

C logs/app.log inside a logs folder

D spring.log in the current directory

💡 Hint

Think about what Spring Boot does if you don't specify any logging file path.

By default, Spring Boot logs only to the console unless you configure a file appender. No log file is created automatically.

❓ Configuration

intermediate

Configuring log file location in application.properties

Which property correctly configures Spring Boot to write logs to a file named 'myapp.log' in the 'logs' folder?

A logging.file=logs/myapp.log

B logging.path=logs/myapp.log

C logging.file.path=logs/myapp.log

D logging.file.name=logs/myapp.log

💡 Hint

Check the exact property name for specifying the log file name.

The property 'logging.file.name' sets the full path and filename for the log file. 'logging.file.path' sets only the directory.

❓ Troubleshoot

advanced

Log file not created despite configuration

You set 'logging.file.name=logs/app.log' in application.properties, but no log file appears after running the app. What is the most likely cause?

A The log level is set to ERROR, so no logs are written

B The 'logs' directory does not exist and Spring Boot does not create it automatically

C The application.properties file is not in the classpath

D Spring Boot requires a separate logging framework dependency to write files

💡 Hint

Think about folder creation behavior for log files.

Spring Boot does not create missing directories for log files automatically. The 'logs' folder must exist before running the app.

🔀 Workflow

advanced

Steps to enable rolling log files in Spring Boot

What is the correct order of steps to configure rolling log files using Logback in Spring Boot?

A 1,3,2,4

B 2,1,3,4

C 1,2,3,4

D 3,1,2,4

💡 Hint

Think about creating config, defining appender, linking it, then restarting.

First create the config file, then define the appender, link it to the logger, and finally restart the app to apply.

✅ Best Practice

expert

Best practice for sensitive data in log files

Which approach is best to avoid logging sensitive information like passwords in Spring Boot file logs?

A Use a custom log filter to mask or remove sensitive data before writing logs

B Set logging.level.root=OFF to disable all logging

C Write sensitive data only to console logs, not files

D Encrypt the entire log file after application shutdown

💡 Hint

Think about controlling what gets logged rather than disabling logging.

A custom log filter can selectively mask or remove sensitive data, keeping logs useful and secure.