config-center

name	config-center
description	ConfigCenter subsystem — ConfCenter trait abstraction, FileSystemCenter and KubernetesCenter implementations, unified Workqueue + ResourceProcessor pipeline.

03 ConfigCenter

The ConfigCenter is a core Controller subsystem responsible for receiving resource configuration from various sources. Both backends share the same Workqueue + ResourceProcessor pipeline; only the event source and persistence layer differ.

ConfCenter Trait Abstraction

The ConfigCenter defines a unified interface via the ConfCenter trait, which contains two groups of capabilities:

• CenterApi — resource CRUD operations: get_one, set_one, create_one, update_one, list
• CenterLifeCycle — lifecycle management: start, ready check, reload, shutdown

Whether the underlying backend is the file system or the Kubernetes API, the upper-layer Workqueue and ResourceProcessor pipeline is identical. Resource changes from the event source enter the Workqueue uniformly for dedup and delayed (coalesced) requeue, then the ResourceProcessor performs validation, preparse, processing, and dispatch.

File List

File	Topic	Recommended reading scenario
00-overview.md	ConfCenter trait architecture	Understanding the ConfigCenter abstraction design
01-file-system.md	FileSystemCenter implementation	Local development / debugging mode
02-kubernetes/	Kubernetes ConfigCenter	Production environments, HA, leader election
(etcd has no standalone document)	EtcdCenter implementation	Non-K8s production, single-Controller deployment

Architecture Comparison

ConfCenter trait
├── CenterApi     (CRUD: get_one, set_one, create_one, update_one, list)
└── CenterLifeCycle (start, ready check, reload, shutdown)

FileSystemCenter      KubernetesCenter         EtcdCenter
├── Local YAML files  ├── K8s API Server        ├── etcd KV store
├── inotify watching  ├── Reflector watch        ├── etcd watch events
├── .status files     ├── Status subresource    ├── No status persistence
├── No leader elect   ├── Lease-based election  ├── No leader election
└── Use: dev/test     └── Use: production K8s   └── Use: non-K8s production

EtcdCenter design constraint: EtcdStorage::create_one/update_one are non-atomic check-then-write operations. The design assumes a single Controller exclusively owns etcd; concurrent writes from multiple Controllers to the same etcd instance are not supported.