Container Monitoring, Logging and Observability

When a containerised system misbehaves, you cannot SSH into a long-lived server and poke around — containers are ephemeral, numerous, and may be gone by the time you look. The only way to understand what happened is to have collected signals about behaviour as it occurred. Observability is the practice of instrumenting systems so their internal state can be inferred from their outputs, and it rests on three pillars: logs (discrete event records), metrics (numeric measurements over time), and traces (the path of a request across services). Without these, a container that crashed at 3am is an unsolvable mystery; with them, you can see the error, the memory spike that preceded it, and which downstream call was slow. Building observability in from the start is what makes a distributed container system operable rather than a black box.