configchange

pkg/controller/configchange

Configuration validation orchestrator and reinitialization signaller.

Overview

ConfigChangeHandler bridges configuration parsing, validation, and controller reinitialization. It does not watch any Kubernetes resource — that's the job of the CRD watcher in pkg/controller. Instead it consumes events:

1. Validation orchestration — subscribes to ConfigParsedEvent, fans a ConfigValidationRequest out to all registered validators (basic, template, jsonpath, validationtests) using the bus's scatter-gather (bus.Request), aggregates the ConfigValidationResponse events, and publishes either ConfigValidatedEvent or ConfigInvalidEvent. When validators report that they couldn't judge the config (ConfigValidationResponse.Inconclusive, e.g. schemas transiently unavailable) and none rejected it, it publishes ConfigValidationInconclusiveEvent, keeps the running config, and validates the same candidate again with backoff (1 s doubling to 30 s) until a verdict arrives or a newer config supersedes it. The scatter-gather can take tens of seconds, so it runs off the event loop — single-flight, latest-wins for parsed configs arriving mid-validation — keeping side events responsive throughout.
2. Reinitialization signal — keeps the running iteration's active snapshot separate from its latest accepted candidate and hands one authoritative snapshot to the controller. Config, credential, and effective-resolution reasons are tracked independently, so superseding a config candidate can't discard a credential or schema reload. Retiring an accepted candidate also replays the active snapshot to state consumers without producing another validation verdict or reload.

This package also contains StatusUpdater, which writes validation results back onto the HAProxyTemplateConfig CRD's status subresource. It runs on the leader only and re-asserts the leader's verdict when another controller (an old version during a rolling upgrade, or a replica's startup load gate) overwrites it for the same or an older generation.

Leadership handover replays the real validation result, including its source generations. A synthetic startup event only seeds an empty replay cache; it cannot replace a validation result or turn an active-state restoration into a new verdict.

Quick Start

import "github.com/haproxy-haptic/HAPTIC/pkg/controller/configchange"

configChangeCh := make(chan *configchange.ReloadRequest, 1)

handler := configchange.NewConfigChangeHandler(
    bus,
    logger,
    configChangeCh,
    []string{"basic", "template", "jsonpath"}, // validator names that must respond
    0,                                         // 0 → DefaultReinitDebounceInterval (2s)
)
go handler.Start(ctx)

// Elsewhere: react to the reinit signal
for request := range configChangeCh {
    // controller restarts its iteration with request.Snapshot
}

The next iteration consumes the snapshot rather than refetching a newer, unvalidated CR. A newer parsed config retracts an accepted candidate until that newer generation passes, while independent credential and schema reloads continue from the active snapshot. Schema changes re-resolve the selected raw config and run the complete config-validation contract before activation. Exact startup-version echoes are ignored; newer changes observed during startup are replayed latest-wins by EnableReinitialization.

Events

• Subscribes: ConfigParsedEvent, ConfigValidatedEvent, BecameLeaderEvent, CredentialsUpdatedEvent
• Publishes: ConfigValidationRequest (scatter), ConfigValidatedEvent, ConfigInvalidEvent, ConfigValidationInconclusiveEvent
• Receives: ConfigValidationResponse (gather — collected via bus.Request, not a registered responder)

License

Apache-2.0 — see root LICENSE.