When and what should I be logging?

This is a follow-up to Sergiy’s post Errors, traces, logs, metrics: when to reach for what.

Modern observability platforms, like Sentry, give developers a lot of choice. For a given problem, should you use traces, profiles, metrics, logs?

If you take away one thing from this post, I hope it’s this: when in doubt, start by adding a few targeted log lines.

Logs are straightforward to add to your application and they’re a fast way to start collecting real information about how your software is running in production. When writing a new feature, I try to add enough logs that it’s debuggable without a deployment.

It’s okay for logs to be temporary instrumentation. Add them when investigating a problem or validating a feature, remove them when they’re no longer useful.