Logging and monitoring in Ruby on Rails - Practice Problems & Coding Challenges

Challenge - 5 Problems

💻 Command Output

intermediate

Understanding Rails Logger Output Level

Given the following Rails logger configuration, what will be the output when a logger.debug message is logged?

config.log_level = :info

Ruby on Rails

logger.debug("Debug message")

A The message will appear in the logs.

B The message will NOT appear in the logs.

C The logger will raise an error due to invalid log level.

D The message will appear only if the environment is development.

💡 Hint

Remember that the log level filters out messages below its severity.

The log level :info means only messages with severity info and above (warn, error, fatal) are logged. Debug messages are below info and thus ignored.

🧠 Conceptual

intermediate

Purpose of Log Rotation in Rails

Why is log rotation important in a Rails application running in production?

A To automatically delete all logs after each request.

B To encrypt log files for security reasons.

C To convert logs into database entries for faster access.

D To prevent log files from growing indefinitely and consuming disk space.

💡 Hint

Think about disk space and log file size.

Log rotation helps keep log files manageable by archiving or deleting old logs, preventing disk space exhaustion.

❓ Troubleshoot

advanced

Diagnosing Missing Logs in Production

A Rails app in production is not showing any logs for errors, even though errors occur. Which configuration issue is the most likely cause?

A The <code>config.consider_all_requests_local</code> is set to <code>true</code>.

B The <code>config.logger</code> is set to <code>Logger.new(STDOUT)</code>.

C The <code>config.log_level</code> is set to <code>:fatal</code>.

D The <code>config.log_tags</code> is missing.

💡 Hint

Check which log levels are recorded.

Setting log_level to :fatal means only fatal errors are logged. Other errors like standard errors may be ignored, causing missing logs.

🔀 Workflow

advanced

Setting Up Basic Monitoring for a Rails App

Which sequence of steps correctly describes setting up basic application monitoring using a tool like New Relic in a Rails app?

A 1,2,3,4

B 2,1,3,4

C 1,3,2,4

D 3,1,2,4

💡 Hint

Think about installation, configuration, restart, then verification.

You first add the gem, configure it, restart the app to load config, then check the dashboard for data.

✅ Best Practice

expert

Choosing the Best Logging Format for Production

Which logging format is best practice for a Rails production app to facilitate log aggregation and analysis?

A JSON formatted logs with structured fields.

B Plain text logs with custom delimiters.

C XML formatted logs for compatibility.

D Binary logs for performance.

💡 Hint

Consider ease of parsing by log management tools.

JSON logs are structured and easily parsed by log aggregation tools, making analysis and searching efficient.