Checking logs via SSH or text files is impossible with 100 containers. You need a Centralized Logging Engine that indexes every line for instant search.
Don't just log text. Log **Structured Data**. - **Bad:** `Log.Information("User " + userId + " logged in");` - **Good:** `Log.Information("User {UserId} logged in", userId);` In Elasticsearch, `UserId` becomes a searchable field. You can then instantly see: 'Show me every error that happened to User 123 across the whole system over the last 7 days.'
Q: "How do you prevent logging from slowing down your application performance?"
Architect Answer: "**Asynchronous Sinks**. We use Serilog with an Async Sink so that the main thread doesn't wait for the log to be written to the network or disk. We also use **Sampling** for high-volume logs (info/debug) and 'Conditional Logging' to ensure that we only log high-detail data when an error actually occurs."