Kubernetes: Objects
Predict what the cluster does next
Four objects and two numbers. A Pod and what its containers share, the chain from a Deployment down to a replaced Pod, a Service that points at labels and has never heard of your Deployment — and then the arithmetic: requests decide where a Pod goes, limits decide what happens to it there.
- Modules
- 4
- Drills
- 4
- Build steps
- 0
- Time
- ~4h
Walk out able to
Say whether a Pod fits on a node, and what becomes of a container that goes past its CPU limit and one that goes past its memory limit.
What you work on
Pods, and what they share
One address, one port space, four things left alone.
Deployments and rollouts
Selectors, the ownership chain, and both rollout bounds.
Services and their ports
Endpoints, readiness, and where a connection lands.
Requests and limits
Placement arithmetic, throttling, QoS and eviction.
The pitch
What you practise, and what you leave with
A capacity plan for four services: requests, limits, the class each Pod lands in, and a node pool that survives its own rollout.
You will practise
- Pods: sharing, restarts and ownership
- Selectors, rollouts and revisions
- Service endpoints, ports and types
- Placement, throttling, QoS and eviction
Afterwards you can
- Say whether a Pod fits, from the numbers
- Bound a rollout, rounded the right way
- Count a Service’s real endpoints
- Tell a throttle from an out-of-memory kill
Modules
4 modules, 23 items
Lessons explain one idea. Drills repeat it until it sticks. Build steps make something that exists afterwards.
- 1
The Pod
~53 minSay what a Pod is, what its containers share, and why you rarely make one yourself.
- LessonWhat this project lets you predict4 min
- LessonPut two containers in one Pod9 min
- LessonName what a Pod leaves alone8 min
- LessonPredict a restart from an exit status8 min
- LessonTell Succeeded from Failed8 min
- LessonDelete it and watch what comes back8 min
- LessonPredict what a deletion leaves8 min
- 2
Deployments and ReplicaSets
~46 minTrace the chain from one edit to a replaced Pod, and bound what a rollout costs.
- DrillCount what a selector claims12 min
- LessonBound a rolling update9 min
- LessonRound each bound its own way9 min
- LessonDecide which edit starts a rollout9 min
- LessonSay why a rollback costs nothing7 min
- 3
A stable address
~39 minSay who is really behind a Service address, and which port a connection lands on.
- LessonFind out who is behind the address10 min
- LessonRule out what a Service is not6 min
- DrillFollow one request through three ports11 min
- LessonPick the type the requirement forces12 min
- 4
Requests place, limits police
~1hDecide whether a Pod schedules, and say what a limit does when a container crosses it.
- LessonWork out where a Pod can go9 min
- LessonFilter, score, or stay Pending9 min
- DrillFit a Deployment onto the nodes14 min
- LessonThrottled, or killed10 min
- LessonPick the number that fixes it7 min
- DrillName the class the numbers put it in12 min
- LessonSize a pool that survives its rollout20 min
More in DevOps & cloud
Keep going
Nginx & Proxies
The config is right. The request went somewhere else.
Advanced~4h6 modules
Linux & Shell
The prompt stops being a place you guess.
Foundational~4h5 modules
Linux: Processes & Systems
Stop guessing why it did not come back.
Intermediate~4h6 modules
Bash Scripting
The line you keep is a different thing from the line you type.
Intermediate~5h5 modules
Stop guessing what the cluster will do next.
The first item is free. ~4h of focused work, at your own pace.
Intermediate~4h4 modules