Engineering / advanced
Reconciliation at cluster scale
Build a precise model of desired state, watches, controllers, admission, ownership, and recovery in a distributed orchestration control plane.
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Inside this module
Module 01 advanced
Reconciliation at cluster scale
Build a precise model of desired state, watches, controllers, admission, ownership, and recovery in a distributed orchestration control plane.
- 01
Reconciliation: restore an invariant from the state you can observe
Design repeatable controller actions that converge toward desired state despite missed events, stale reads, and uncertain external outcomes.
25 min - 02
API concurrency: treat resourceVersion as an opaque token
Handle update conflicts by rereading and recomputing intent without turning API version tokens into timestamps or cross-object clocks.
25 min - 03
List and watch: rebuild state when history expires
Establish a collection baseline, resume supported watches, and handle lost history without mistaking bookmarks for periodic heartbeats.
25 min - 04
Work queues: coalesce keys and slow failing retries
Reason about dirty keys, processing completion, rate limiting, and fair recovery without treating notifications as one task each.
25 min - 05
Finalizers: make deletion wait for verifiable cleanup
Trace deletion timestamps and controller-owned cleanup while avoiding duplicate side effects and unsafe forced removal.
25 min - 06
Ownership: follow object UIDs through dependent lifecycles
Separate labels from ownership, apply namespace rules, and reason about foreground, background, and orphan deletion.
25 min - 07
Admission: mutate safely, then validate the resulting object
Separate authentication, authorization, mutation, validation, and persistence while handling reinvocation and webhook failure deliberately.
25 min - 08
Controller leadership: a lease does not fence old work
Trace cooperative leadership changes and require downstream fencing or idempotency for effects that must exclude a stale actor.
25 min - 09
Control-plane storage: history, watches, and write amplification
Budget logical churn and retained versions while separating Kubernetes API tokens from etcd’s documented revision model.
25 min - 10
Controller tests: attack the lifecycle boundaries
Build invariant-based scenarios for stale reads, conflicts, retries, deletion races, and stale leaders using the right test environment.
25 min