Why logs matter?

When things go wrong in software systems (and they will), logs often hold the key to understanding what happened, why it happened, and how to fix it. Yet, logging is frequently treated as an afterthought. I think logs should be treated as a first class citizen in our codebases.

Why Logging Matters

Logs are like a time machine for developers. They help us:

• Trace bugs in production without needing to reproduce them locally.
• Monitor system health through patterns and anomalies.
• Understand user behavior and usage trends.
• Audit critical actions and maintain security compliance.

Good logs give you visibility into what your code is doing, in real time and over time.

Choosing the Right Log Level

Logging everything is just as bad as logging nothing. That's why log levels exist. Here's a quick rundown:

• DEBUG: Detailed information for diagnosing problems. Use liberally during development.
• INFO: Routine operations like service start up, shutdown, or config loading.
• WARN: Something unexpected happened, but the app can recover.
• ERROR: Something failed. Action is likely needed.
• FATAL / CRITICAL: The system is in a non recoverable state and will likely terminate.

Pick the right level so you’re not drowning in noise nor missing the signal.

Practical Tips

• Add context: Include IDs, timestamps, and state when relevant.
• Avoid logging sensitive data: Don't make your system vulnerable.
• Use structured logs (JSON) if your platform supports it.
• Regularly review and prune noisy or redundant logs.

Final Thoughts

Logs are more than just messages. They’re your insight into the invisible workings of your software. Write them well, and they’ll save your future self (and your teammates) countless hours of debugging. Up next: I’ll be writing about metrics and audit logs — the other pillars of good observability.

What’s your philosophy on logs? Got any interesting stories to share?