What methods can be used to determine the causes of a service failure or crash?

Several approaches can be used to identify the causes of service failure or crash:

• Logging: analyzing application logs and system logs helps identify errors and exceptions that led to the failure.
• Monitoring and metrics: using monitoring systems (e.g., Prometheus, Grafana) to track the service's status, CPU load, memory, request count, and errors.
• Tracing: distributed tracing of requests helps understand at which stage the failure occurred.
• Debugging and profiling: running the application in debug mode or profiling to identify bottlenecks and errors.
• Memory dump and stack analysis: upon crash, analyzing memory dumps or call stacks can help determine the cause.

Example of simple logging in Python:

import logging

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

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