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Running stateful apps with StatefulSets
Stateful apps need stable identity and storage; a StatefulSet gives stable names, ordered rollout, and per-Pod volumes.
Persistent Volume and Persistent Volume Claim
Kubernetes separates storage provisioning from consumption. A PersistentVolume is a cluster storage resource an admin or driver provisions; a PersistentVolumeClaim is a pod's request for storage.
What a service mesh solves
It adds traffic management, security via mTLS, and observability at the network layer through sidecars, beyond what plain Kubernetes offers.
What is a Custom Resource Definition?
A CRD registers a new resource kind so the API server stores and serves it like built-ins; it lets you model domain concepts declaratively.
What is a Helm chart?
A chart is a templated, versioned bundle of manifests with a values file; it solves config duplication and reuse across environments.
Spreading Pods one-per-node for availability
Use required podAntiAffinity with topologyKey kubernetes.io/hostname matching the Deployment's own pod labels, so the scheduler refuses to co-locate two Pods on a node.
CRDs and the Operator pattern
CRDs add new API object types, an Operator pairs a CRD with a controller that runs a reconciliation loop encoding domain operational knowledge.
Inference Health Checks: Traffic Gates, Not Heartbeats
An inference server's health check is a traffic gate, not a heartbeat. Kubernetes uses it to route requests only after the model is loaded. The footgun is probing the root path, which stays green even when the model has crashed or the GPU is wedged.
Pod QoS Classes: Guaranteed, Burstable, BestEffort
Kubernetes QoS classes are eviction priorities, not performance guarantees. Under node pressure, the kubelet kills BestEffort pods first, then Burstable, then Guaranteed. Omitting limits does not grant infinite headroom; it makes your pod die first.
What problem can a breaking API change cause during a rolling update?
Tests if you know rolling updates run mixed versions, so breaking API changes crash cross-traffic. Good answer: note old and new pods serve together, watch probes fail, and monitor 5xx spikes. Red flag: claiming Kubernetes isolates versions during rollout.
How does your app authenticate with secrets management and solve secret zero?
This tests platform trust chains and the bootstrap credential problem. A strong answer names IAM, Kubernetes, or AppRole auth, explains platform attestation, and uses short-lived tokens.
Health Check Endpoints: Reporting App Status
A health check is a dedicated endpoint that tells an orchestrator if your app is alive and ready for traffic. Systems like Kubernetes use it to decide whether to send traffic (readiness) or restart a container (liveness).
Chaos Mesh: Orchestrated Failure for Resilient Systems
Chaos Mesh is a disaster-as-a-service for Kubernetes. It lets you inject failures like network latency or pod kills to test system resilience. Use it to find weaknesses before they impact users, but be warned: its job is to break things, so scope experiments…
Declarative vs. Imperative Automation
Declarative automation defines the desired end state (“what”), not the steps to get there (“how”). It's used in tools like Kubernetes to manage complex infrastructure, letting the system figure out the details.
Prometheus: Monitoring with a Dimensional Data Model
Prometheus models system health as labeled time series, not just flat metrics. It pulls data from targets, making it ideal for dynamic cloud environments like Kubernetes. The footgun is using high-cardinality labels, which can overwhelm its storage.
SPIFFE: Cryptographic Identity for Services
SPIFFE gives every service a cryptographic passport instead of a static secret. It's used in zero-trust networks for services to authenticate each other, like in a Kubernetes service mesh.
The Operator Pattern: A Robot SRE for Your App
The Operator pattern adds a custom, automated "robot SRE" to your Kubernetes cluster. It encodes human operational knowledge for a specific application, like a database, into software that handles complex tasks like upgrades, backups, and failovers…
Helm Post-Rendering: Customize Charts Without Forks
Helm post-rendering lets you modify a chart's Kubernetes manifests just before deployment. It's ideal for applying kustomize patches or injecting sidecars without forking a public chart.
Helm Hooks: Running Operations During a Release
Helm Hooks are Kubernetes resources that run at specific moments in a release lifecycle. Use them to run a database migration before an app upgrade or to back up data before a deletion. The footgun: a failing hook Job will block and fail the entire.
Helm Subcharts: Composing Applications from Dependencies
Helm subcharts are nested components a parent chart can configure, like a docker-compose for Kubernetes manifests. Use them to bundle dependencies like a database with your app. The footgun: subcharts are sandboxed and cannot access parent values directly.