Container logging and monitoring encompasses the practices, tools, and patterns for collecting, aggregating, and analyzing logs, metrics, and traces from containerized applications running in Docker, Kubernetes, and orchestrated environments. Unlike traditional monolithic applications where logs and metrics reside on persistent hosts, containers are ephemeral and stateless — they start, stop, and restart frequently, making centralized collection essential. Modern container observability relies on stdout/stderr streams as the standard output mechanism, log drivers to route data, health probes to ensure availability, and metrics exporters to track resource consumption. Understanding this ecosystem is critical because improper logging configuration can lead to disk exhaustion, lost diagnostics during crashes, and inability to trace requests across distributed microservices.
What This Cheat Sheet Covers
This topic spans 15 focused tables and 125 indexed concepts. Below is a complete table-by-table outline of this topic, spanning foundational concepts through advanced details.
Table 1: Container Log Output Streams
| Concept | Example | Description |
|---|---|---|
echo "Request processed" > /dev/stdout | • Standard output stream where applications write normal log messages • captured automatically by the container runtime. | |
echo "Error occurred" >&2 | • Standard error stream for error and warning messages • also captured by runtime and often displayed separately in log tools. | |
console.log("msg") writes to stdout | • Treats logs as event streams written to stdout/stderr • no file management inside containers — the platform collects them. |