Courses
Short packs on what everything else takes for granted. Buy once, keep forever.
Courses
Each one stands on its own. Start with any of them.
Linux Fundamentals
Move around a system, read permissions, watch processes and find out why something failed.
Bash Fundamentals
Quoting, pipes and redirection — and why a filename with a space breaks a script.
Git Fundamentals
The mental model that makes predictable what otherwise looks like black magic.
Building a Harness
Assemble a working agent harness from scratch in Python: the loop, a versioned system prompt, a tool surface, a sandbox and permission modes, hooks, subagents, compaction, and the traces that let you debug it.
Agent Tools
The agent loop, tool descriptions and schemas, error handling, parallel calls, and how to design a tool surface you can still say no to.
Context Engineering
Token budgets, prompt caching and what silently breaks it, pruning versus summarising, memory between sessions, and keeping tool output out of the window.
Evaluating AI Agents
Building a test set, deterministic checks before model judges, rubrics that discriminate, measuring the trajectory, and cost and latency as results.
Prompt Injection
Why no parser separates instructions from data, where untrusted text enters, why delimiters are not a boundary, and how to design so a landed instruction cannot do damage.
Agent Permissions
Blast radius, least privilege per tool, the confused deputy, secrets the agent must never see, egress control and an audit trail you can read months later.
Data Protection for AI Systems
What crosses the wire, what ends up in logs, retention and training terms, redaction, residency, and deleting a record that was already embedded into an index.
CKA Exam Mechanics
The format, the domain weights, context switching, using the documentation, what to skip, and how to verify a task before moving on.
Fast kubectl
Generating manifests instead of typing them, the imperative command set, editing running objects, jsonpath, and reading a broken object in the right order.
CKA Task Drills
Exam-shaped tasks across RBAC, workloads, scheduling, services, network policies, storage, troubleshooting and cluster operations — each with its minimal sequence and its trap.
Containers
Images, layers, the build cache, volumes, networking and users — and how to build a small image that stops cleanly.
Kubernetes Fundamentals
Reconciliation, pods, deployments, services, ingress, config and secrets, requests and limits, probes, storage and RBAC.
Kubernetes Troubleshooting
Pending, ImagePullBackOff, CrashLoopBackOff, exit code 137, lying probes, empty Services, cluster DNS, evictions and stuck rollouts.
Networking Fundamentals
Addresses, routing, ports, TCP and UDP, DNS and its caches, TLS and certificate errors — and a method for turning «it doesn't connect» into a question you can answer.
HTTP in Practice
Status codes that lie, caching, cookies and sessions, CORS, redirect loops, proxies and what HTTP/2 and HTTP/3 did and did not change.
Networking Troubleshooting
Where the time goes, latency against bandwidth, MTU black holes, keepalives, packet loss, tcpdump and reading a capture, exhausted connections and intermittent failures.
Metrics, Logs and Traces
What each signal answers, why percentiles beat averages, how histograms work, and where cardinality and sampling send the bill.
SLOs and Alerts
Indicators, targets, error budgets, burn-rate alerting, what an alert must contain, and who gets woken up.
Incident Response
The first five minutes, blast radius, cascades, graphs that mislead, partial failures, mitigation, communication and the post-mortem.
Packs
Several courses on one topic, bought once.
AI Agents
On saleTool design, context and cost, and how to evaluate an agent without fooling yourself. Three courses, 30 lessons.
AI Security
On salePrompt injection, what an agent can reach when it is compromised, and where your data actually goes. Assumes the AI Agents pack. Three courses, 30 lessons.
CKA Exam Prep
On saleExam mechanics, fast kubectl and task drills for the Certified Kubernetes Administrator. Assumes the Kubernetes pack; does not replace practising on a real cluster. Three courses, 30 lessons.
Fundamentals
FreeLinux, Bash and Git, interactive. Free once you sign up.
Harness Engineering
FreeBuild the layer that turns a model into an agent — the loop, the prompt, the tool surface, the sandbox, subagents and compaction. One course, 10 lessons.
Kubernetes
On saleContainers, the Kubernetes model and how to diagnose a failing cluster. Three courses, 32 lessons.
Networking
On saleHow a packet gets there, what goes wrong with HTTP, and how to diagnose a connection that fails intermittently. Three courses, 30 lessons.
Observability
On saleMetrics, logs and traces; SLOs and alerts; and what to do during an incident. Three courses, 30 lessons.