
An instrumented system is not a safe system until it has been loaded on purpose. This lecture turns the load drill into a program — four steps from forty-five to one hundred fifty requests per second — and judges it with three saturation gate rules on connections, p ninety-nine latency, and errors. The first three steps pass; the last fails line by line, with connections pinned at one hundred of one hundred, a wait queue fourteen deep, and p ninety-nine at one point nine seconds. Little's law then sizes the honest fix — an app-side pool of sixty for the storefront service, against the PostgreSQL hundred-connection ceiling the drill counts — and the lecture defends the verdict, DO NOT SHIP THE SALE, as the drill succeeding, not failing. AI disclosure: this course's narration uses a cloned voice of the instructor, created with the instructor's consent; all content, code, and curriculum are authored and verified by the instructor team. Music: "Frozen Star" by Kevin MacLeod — CC BY 4.0
This is the hunt the sampling policy was bought for. Starting from the sale-day board — p ninety-nine at four point two seconds, errors at six point five percent, CPU green the entire time — you jump from the latency histogram's exemplars to the single trace that matters: four thousand one hundred eighty milliseconds across fifty-three spans, forty-seven of them inventory database spans of roughly eighty-four milliseconds each. Logs pulled by trace identity confirm the loop shipped in the sale-day deploy, and the root cause turns out to be two failures wearing one coat: an N+1 query loop, and the inventory service's own app-side connection pool capped at ten — ten borrowed connections at a time out of the database's shared hundred-connection ceiling. AI disclosure: this course's narration uses a cloned voice of the instructor, created with the instructor's consent; all content, code, and curriculum are authored and verified by the instructor team. Music: "Frozen Star" by Kevin MacLeod — CC BY 4.0
A fix is a hypothesis until two boards sign it. This lecture builds the prove board for SwiftCart's sale-day repair — the batched query and the pool raised from ten to forty — and reads it line by line: p ninety-nine from four point two seconds to five hundred eighty milliseconds, errors from six point five percent to zero point zero seven, spans from fifty-three to seven, database spans from forty-seven to one. Then the Lecture 13 load drill is re-run with the fix in place, and at one hundred fifty requests per second it passes: p ninety-nine seven hundred ten milliseconds, database connections sixty-one of the shared hundred. Only then is the fix signed — and the lecture closes on what unsigned fixes look like in the wild. AI disclosure: this course's narration uses a cloned voice of the instructor, created with the instructor's consent; all content, code, and curriculum are authored and verified by the instructor team. Music: "Frozen Star" by Kevin MacLeod — CC BY 4.0
Project 3 begins by choosing service level indicators from the golden signals you already measure, then setting SwiftCart's two service level objectives: ninety-nine point nine percent availability and ninety-five percent of checkout requests under three hundred milliseconds. You derive the error budget in both units — forty-three point two minutes and one hundred seventeen thousand failed requests a month — derive burn rate live as error ratio divided by budget ratio, and see why fourteen point four times burn consumes two percent of the budget in an hour. The lecture closes with an alert audit: ten paging rules become six symptom-based pages, and the four cause-based pages are struck — CPU and pod restarts deleted outright, disk and queue depth demoted to tickets — the CPU page among them having fired eleven times with zero user impact. AI disclosure: this course's narration uses a cloned voice of the instructor, created with the instructor's consent; all content, code, and curriculum are authored and verified by the instructor team. Music: "Frozen Star" by Kevin MacLeod — CC BY 4.0
An interview incident walked minute by minute, exactly as you should narrate it. A canary deploy lands at zero two forty-seven on five percent of traffic; the canary pods sit on a node being drained, their inventory calls time out and retry, and the burn concentrates in the canary slice. At zero three twelve the fourteen point four times burn alert pages. Working the method from Lecture 9 — symptom, scope, recent change, trace, mitigate, verify — the scope step isolates the canary slice, rollback completes at zero three twenty-three, eleven minutes from page to mitigated, and the budget line reads about half a budget-minute consumed — roughly zero point five of forty-three point two minutes, about one point two percent. The lecture closes on what the interviewer is actually scoring: method, not heroics. AI disclosure: this course's narration uses a cloned voice of the instructor, created with the instructor's consent; all content, code, and curriculum are authored and verified by the instructor team. Music: "Frozen Star" by Kevin MacLeod — CC BY 4.0
This course contains the use of artificial intelligence.
Your dashboards were green. Your users were failing. That gap — between what your graphs said and what your customers felt — is where production careers are made and lost, and closing it is a learnable engineering discipline. This course teaches it the way it is practised: on one running system, with every claim measured on a board, a drill, or a trace you can read yourself.
**The core ten lectures** build the discipline in order: why monitoring is not observability; the four golden signals and the RED/USE methods that tell you what to measure first; Prometheus metrics without the cardinality trap that melts servers (one label, multiplied by 2.1 million users, is 1.3 billion series — you will do that multiplication yourself); logs that earn their keep, structured and carrying trace IDs; distributed tracing with OpenTelemetry; dashboards built as answers to questions instead of walls of charts; alerting that pages on symptoms, not causes; SLOs and error budgets — the numbers that end arguments between product and engineering; a six-step incident method; and the full-stack blueprint with its sampling and retention economics priced out.
**Then you work three production projects on SwiftCart, one running example system you reproduce locally from fixtures.** Project 1: you write the telemetry contract, census its twelve signal groups, build RED metrics and the four-panel Grafana dashboard — then run the load drill that finds the saturation wall at 150 requests per second in an afternoon, instead of letting the sale find it in production. Project 2: you price full trace capture (31 gigabytes a day), design the sampling policy that cuts it to 3.4, and hunt the incident through a single 53-span trace to the 47 database calls an N+1 deploy was hiding — then prove the fix on a signed before/after board. Project 3: you set a 99.9% SLO, turn its 43.2-minute error budget into burn-rate alerts that page at 14.4× and ticket at 3×, strike the four cause-based paging rules — including a CPU page that cried wolf eleven times in a month with zero user impact — and pass PagerGate, a five-gate ship board you will watch fail three sabotage drills on purpose.
**Then you crack the interview.** Four lectures with the arithmetic done live: observability for a payments platform at 5,000 requests per second (432 million requests a day, budgeted to the series), a 3 a.m. incident debugged minute-by-minute — paged at 03:12, rolled back by 03:23, about half a budget-minute spent (≈1.2% of the month's budget) — whiteboard SLO and telemetry-cost math, and a five-move playbook with a ten-question rapid-fire drawn from the whole course.
Every number in this course comes from the system on screen — census counts, drill boards, trace trees, budget tables. Nothing is asserted from memory. You also get downloadable code and exercise books, six quizzes — four checkpoints, an interview primer and a cumulative final, with a 70% mastery rule on the checkpoints and the final — five hands-on assignments with worked solutions, and a capstone: make your own production system observable, behind your own PagerGate.
AI disclosure: this course's narration uses a cloned voice of the instructor, created with the instructor's consent; all content, code, and curriculum are authored and verified by the instructor team.