How did you find out that something was breaking or degrading? What did you look at?

To detect failures or degradation in code or system operation, several approaches are usually used:

• Logs and Monitoring: Viewing application logs, system logs, as well as performance metrics (CPU, memory, response time). Tools like Prometheus, Grafana, ELK Stack are often used for this.

• Automatic Alerts: Setting up notifications when threshold values of metrics are reached or errors occur.

• Testing: Regularly running unit tests, integration tests, and performance tests to identify regressions.

• Profiling and Tracing: Using profilers and tracers to identify bottlenecks and anomalies.

For example, with Python, logs can be viewed through the standard logging module, and monitoring can be done using external services. If the application starts responding slower or errors appear, this will be visible in logs and metrics.

A simple example of logging in Python:

import logging

logging.basicConfig(level=logging.INFO, filename='app.log')

try:
    # code
    pass
except Exception as e:
    logging.error(f"Error: {e}")