Environments, configuration, and secrets management
By the end of today you can separate configuration from code so one build runs correctly everywhere, and explain what to do the moment a secret leaks.
YesterdayOn Day 51 you built one artefact and shipped it. Today that same artefact behaves correctly in three different places.
TomorrowTomorrow, seeing what that deployed system is actually doing.
Why this matters
Configuration mistakes cause outages that look like code bugs and waste hours. Getting the boundary right once removes a whole category of confusion.
- Configuration against code
- Environment parity
- Rotating a leaked secret
- Feature flags
Learn it
75 minCopy this into Claude or ChatGPT. It quizzes you before it explains anything, which is deliberate. The resources under it are how you check what it told you.
Today's Master Prompt
Free · sign inA prompt written for this day alone: your level, the exact scope, what to leave out, and an instruction to quiz you before it explains anything. Paste it into Claude or ChatGPT and it teaches you today's material.
Check it against something that is not a model
An assistant can be fluent and wrong, and on a topic you met today you will not catch it. These cover the same ground and were made by people who do this for a living, so they are what you hold the explanation up against. They are other people's work and we only link to them, so judge them for yourself.
3 hand-picked resources
Free · sign inVideos, official docs and articles covering the same ground, each opened and annotated by hand. They are what you check the assistant against on a day you cannot yet catch it being wrong.
Build it
45 minMove every environment-specific value in your API out of code and into environment variables, validated at startup so the app refuses to boot with a clear message if any is missing or malformed. Then run it with a variable deliberately absent and confirm the failure is immediate and readable.
Recall it
20 minAnswer out loud, reveal, then mark honestly whether you had it. That score is the only thing on this page you do not get to choose.
5 recall questions
Free · sign inQuestions you answer from memory, then grade yourself against the real answer. The score is carried into the mastery rating below it, so an honest miss cannot quietly become a tick.
Rate it
Completion and mastery are tracked separately. Be honest, because an inflated rating only means the concept resurfaces sooner.
Mastery tracking
Free · sign inRate yourself against five named criteria per concept. Completion and mastery are tracked separately, and anything you rate shakily comes back automatically on a spaced schedule.
Recap
- 01Configuration is what differs between deployments, and it lives outside the code
- 02Build once, configure per environment, or you ship what you never tested
- 03Validate at startup so failures are immediate and named
- 04A leaked secret is rotated first and cleaned up second
Your progress
Free · sign inMark days complete, pick up where you left off across devices, and watch completion and mastery diverge. Free, and the account exists only so ninety days of work cannot vanish with a cleared browser.