Easy everything in DevOps & Cloud, page 2
Core components of Prometheus
Server scrapes targets found via service discovery, stores samples in a local time-series database, with Alertmanager and exporters as helpers.
Essential tags for a request latency metric
Add method, route template, status code, and maybe service or region; they enable slicing while staying low-cardinality.
Structured vs unstructured logging
Unstructured logs are free-text lines; structured logs are machine-readable key-value or JSON, enabling reliable parsing, filtering, and aggregation.
The three pillars of observability
Metrics show what and when via cheap aggregates, logs give detailed per-event context, traces show where across services.
Proposing availability and latency SLIs for an auth API
Availability as the ratio of successful valid requests; latency as the fraction served under a threshold; measure at the edge from the user's view.
What is an error budget?
Error budget is one minus the SLO, the allowed unreliability; it gates feature velocity versus reliability work.
Relationship between SLI, SLO, and SLA
SLI is the measured metric, SLO is the internal target for that metric, SLA is the external contract with consequences.
What are the Four Golden Signals?
Name latency, traffic, errors, and saturation; explain each briefly; describe measuring latency as a distribution separating success from failure.
Explain the three pillars of observability
Metrics are cheap aggregated time series for detecting and alerting, logs are discrete event records for detail and context, traces follow one request across services to localize latency.
How do SRE and DevOps relate?
DevOps is a broad culture of breaking down silos; SRE is one prescriptive way to do it with specific practices.
SLI vs SLO vs SLA: how do they relate?
SLI is a measured metric, SLO is the internal target for that metric, SLA is the external contract with consequences.
What defines toil, with an example?
Define toil as manual, repetitive, automatable, tactical, no-enduring-value, scaling-with-growth work; distinguish it from overhead; give a concrete example.
kube-state-metrics versus node-exporter
Kube-state-metrics exposes API object state (deployment replicas, pod phase, restarts) from the control plane, while node-exporter exposes OS-level hardware metrics (CPU, memory, disk) per…
Viewing pod logs and durable log collection
Kubectl logs (with -c, --previous, -f) reads container stdout/stderr; because that storage is ephemeral, run a node-level logging agent as a DaemonSet shipping logs to a central store.
First NetworkPolicy flips a pod to default-deny
Once any policy selects a pod for a direction, that direction becomes default-deny and only explicitly allowed traffic passes; unselected pods stay open.
Role versus ClusterRole in RBAC
Role is namespaced, ClusterRole is cluster-wide and covers cluster-scoped resources, and you grant either via a RoleBinding (namespaced) or ClusterRoleBinding (cluster-wide) to a subject.
How do you stop new Pods scheduling on a node?
Kubectl cordon marks the node unschedulable so no new Pods land, while existing Pods keep running; drain is the follow-up that also evicts them.
How do you pin a Pod to nodes with a given label?
The simplest tool is nodeSelector, a key-value map in the Pod spec requiring matching node labels; node affinity is the richer alternative for complex rules.
Requests vs limits for CPU and memory?
Requests guide scheduling and reservation, limits cap usage; exceeding a CPU limit throttles the container, while exceeding a memory limit triggers an OOMKill since memory is incompressible.
Bind mounts vs named volumes for persisting Docker data?
Persist data outside the writable container layer via a bind mount (a host path you control) or a named volume (Docker-managed under its data dir, portable and the recommended default).
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