Interview questions
Containers, orchestration and delivery pipelines.
Docker packages an application and its dependencies into an image that runs as an isolated container. Containers share the host operating system kernel and isolate processes with namespaces and cgroups, so they start in seconds and are lightweight. Virtual machines virtualise hardware and run a full guest OS, giving stronger isolation at a higher resource cost.
Kubernetes orchestrates containers across a cluster. Pods are the smallest unit and run one or more containers. Deployments manage replica sets for rolling updates, Services give pods stable networking, and ConfigMaps and Secrets inject configuration. The control plane continuously reconciles the actual state of the cluster towards the desired state you declare.
Continuous integration merges changes frequently and verifies each one automatically with builds and tests. Continuous delivery keeps every passing build deployable; continuous deployment releases it automatically. A good pipeline is fast, reproducible and trustworthy: cached builds, meaningful test stages, security checks, immutable artefacts promoted between environments, and safe rollouts with quick rollback.
Observability is the ability to understand a system’s internal state from its outputs. Metrics are numeric time series for dashboards and alerts, such as latency and error rate. Logs are detailed event records for investigating specific cases. Traces follow one request across services to show where time is spent. Together they answer what, where and why.
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