Docker &amp; Kubernetes

Kubernetes Cluster-Level Logging

Cluster-level logging treats logs as a stream, not as files on ephemeral pods. It centralizes logs from all nodes before they disappear when a pod dies, which is essential for debugging any production application.

Prometheus Architecture: A Pull-Based Monitoring System

Prometheus is a monitoring system that actively pulls metrics from your services, rather than waiting for them to push data. It's the standard for tracking performance in dynamic environments like Kubernetes.

Prometheus Exporters: Translating Metrics for Monitoring

A Prometheus Exporter is a translator, converting metrics from third-party systems like databases or hardware into the format Prometheus can scrape. Use one when you can't modify an app's code directly.

cAdvisor: A Task Manager for Containers

cAdvisor is like a task manager for your containers, giving you a live view of their resource usage. It's used to track performance, historical usage, and network stats for every container on a host.

PromQL: Querying Time Series Data as Vectors

PromQL treats metrics as vectors of values over time, letting you slice and aggregate system state. It's used for Grafana dashboards and Alertmanager rules. The footgun: applying rate() to a gauge instead of a counter produces silent, nonsensical results.

Prometheus Alertmanager: Taming Your Alert Storms

Alertmanager is the traffic controller for your Prometheus alerts, turning a potential flood into actionable notifications. It groups, deduplicates, and routes alerts to services like PagerDuty. The footgun: don't load balance traffic to an HA cluster.

OpenTelemetry

OpenTelemetry is a CNCF standard for generating, collecting and exporting traces, metrics and logs from your services using one vendor neutral set of APIs and SDKs, so you can switch observability backends without rewriting instrumentation code.

Service Mesh Observability: Seeing Inside the Black Box

A service mesh provides observability by intercepting all service-to-service traffic. It automatically generates logs, metrics, and traces, helping you debug distributed systems without changing application code.

GitOps Principles: Your Repo as the Source of Truth

GitOps treats infrastructure state like code, with your Git repo as the single source of truth. Automated agents pull declarative configs from the repo to reconcile the live system, making it ideal for Kubernetes.

Helm: The Package Manager for Kubernetes

Helm is like apt or Homebrew for Kubernetes. It bundles all your app's YAML files into a single manageable package called a Chart, solving "YAML sprawl." Use it to install complex apps with one command or to package your own for repeatable deployments.

Helm Repository: Your Private App Store for Kubernetes

A Helm repository is a private app store for your Kubernetes applications. It's just an HTTP server with a catalog file (index.yaml) pointing to your packaged charts. Use it to share reusable app templates across teams without using public registries.

Helm Templates: Turning Static YAML into Dynamic Manifests

Think of Helm templating as a mail merge for Kubernetes. It combines static YAML templates with dynamic values to generate manifests for different environments. Use it to manage configurations for dev, staging, and prod.

Configuration Drift: When Live State Betrays Git

Configuration drift is when your live system's state no longer matches its Git source of truth. GitOps tools like Argo CD detect this by constantly comparing live resources to Git, flagging any discrepancies.

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.

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.

Argo CD Sync Phases and Waves: Ordering Your Deployments

Argo CD Sync Phases and Waves are a recipe for ordering deployments. Use them for complex apps where a database migration must run pre-sync. The footgun: a single failed resource in a wave halts the entire sync process, making it brittle if overused.

Flux Image Update Automation: Closing the GitOps Loop

Flux's image update automation acts like a bot that watches your container registry. It finds new image tags that match your policies (like semver) and automatically commits the change back to your Git repository, triggering a deployment.

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.

Custom Resource Definitions (CRDs): Teach Kubernetes New Tricks

CRDs let you define your own resource types, teaching Kubernetes new nouns like Database or Backup. This is how operators manage complex apps declaratively. The footgun is that a CRD only defines the API; you still need a controller to act on the objects.