configloader

README

pkg/controller/configloader

ConfigLoader component - parses ConfigMap data into configuration structures.

Overview

Event-driven component that subscribes to ConfigResourceChangedEvent, extracts YAML configuration from ConfigMap resources, and publishes ConfigParsedEvent for valid configurations.

Part of: Stage 1 (Config Management) in controller lifecycle

Installation

import "haptic/pkg/controller/configloader"

Quick Start

import (
    "haptic/pkg/controller/configloader"
    "haptic/pkg/events"
)

// Create component
loader := configloader.NewConfigLoaderComponent(bus, logger)

// Start component (blocks until context cancelled)
go loader.Start(ctx)

// Component automatically processes ConfigResourceChangedEvent
// and publishes ConfigParsedEvent

API

NewConfigLoaderComponent

func NewConfigLoaderComponent(bus *busevents.EventBus, logger *slog.Logger) *ConfigLoaderComponent

Creates a new ConfigLoader component.

Parameters:

• bus: EventBus for subscribing and publishing
• logger: Structured logger for diagnostics

Returns: ConfigLoaderComponent ready to start

Start

func (c *ConfigLoaderComponent) Start(ctx context.Context) error

Starts the component's event loop. Blocks until context is cancelled. Returns nil on graceful shutdown.

Process:

1. Subscribes to EventBus
2. Waits for ConfigResourceChangedEvent
3. Extracts ConfigMap data["config"]
4. Parses YAML using config.ParseConfig
5. Publishes ConfigParsedEvent on success

Stop

func (c *ConfigLoaderComponent) Stop()

Gracefully stops the component.

Events

Subscribes To

ConfigResourceChangedEvent:

type ConfigResourceChangedEvent struct {
    Resource interface{}  // *unstructured.Unstructured (ConfigMap)
}

Published by ConfigChange watcher when ConfigMap changes.

Publishes

ConfigParsedEvent (on success):

type ConfigParsedEvent struct {
    Config        *config.Config
    ConfigVersion string  // ConfigMap resourceVersion
    SecretVersion string  // Empty at this stage
}

Published when YAML successfully parsed into config.Config.

ConfigMap Format

Expected ConfigMap structure:

apiVersion: v1
kind: ConfigMap
metadata:
  name: haproxy-config
  namespace: default
data:
  config: |
    templates:
      main: |
        global
          maxconn 2000
        defaults
          mode http
    watched_resources:
      - name: ingresses
        group: networking.k8s.io
        version: v1
        resource: ingresses

Required:

• data.config: YAML configuration string

Error Handling

Component logs errors but does not publish events for failures:

Missing "config" key:

Error: ConfigMap data missing 'config' key

Invalid YAML:

Error: Failed to parse configuration YAML

Invalid resource type:

Error: ConfigResourceChangedEvent contains invalid resource type

No data field:

Error: ConfigMap has no data field

Example Usage

Basic Setup

func main() {
    bus := events.NewEventBus(100)
    logger := slog.Default()

    loader := configloader.NewConfigLoaderComponent(bus, logger)

    ctx, cancel := context.WithCancel(context.Background())
    defer cancel()

    go loader.Start(ctx)

    // Wait for ConfigParsedEvent
    eventChan := bus.Subscribe(10)
    for event := range eventChan {
        if parsed, ok := event.(*events.ConfigParsedEvent); ok {
            fmt.Printf("Config loaded: version %s\n", parsed.ConfigVersion)
        }
    }
}

Integration

Controller creates ConfigLoader in Stage 1:

// Stage 1: Config Management
configLoader := configloader.NewConfigLoaderComponent(bus, logger)
go configLoader.Start(ctx)

Component runs for entire controller lifecycle, processing ConfigMap updates.

License

See main repository for license information.

Documentation

Index

• Constants
• type ConfigLoaderComponent
  • func NewConfigLoaderComponent(eventBus *busevents.EventBus, logger *slog.Logger) *ConfigLoaderComponent
  • func (c *ConfigLoaderComponent) Start(ctx context.Context) error
  • func (c *ConfigLoaderComponent) Stop()

Constants

const (
	// ComponentName is the unique identifier for this component.
	ComponentName = "configloader"

	// EventBufferSize is the size of the event subscription buffer.
	// Size 50: Low-volume component (~1 event per config change).
	EventBufferSize = 50
)

Types

type ConfigLoaderComponent

type ConfigLoaderComponent struct {
	// contains filtered or unexported fields
}

ConfigLoaderComponent subscribes to ConfigResourceChangedEvent and parses config data.

This component is responsible for: - Converting HAProxyTemplateConfig CRD Spec to config.Config - Publishing ConfigParsedEvent for successfully parsed configs - Logging errors for conversion failures

Architecture: This is a pure event-driven component with no knowledge of watchers or Kubernetes. It simply reacts to ConfigResourceChangedEvent and produces ConfigParsedEvent.

func NewConfigLoaderComponent

func NewConfigLoaderComponent(eventBus *busevents.EventBus, logger *slog.Logger) *ConfigLoaderComponent

NewConfigLoaderComponent creates a new ConfigLoader component.

Parameters:

• eventBus: The EventBus to subscribe to and publish on
• logger: Structured logger for diagnostics

Returns:

• *ConfigLoaderComponent ready to start

func (*ConfigLoaderComponent) Start

func (c *ConfigLoaderComponent) Start(ctx context.Context) error

Start begins processing events from the EventBus.

This method blocks until Stop() is called or the context is canceled. The component is already subscribed to the EventBus (subscription happens in constructor). Returns nil on graceful shutdown.

Example:

go component.Start(ctx)

func (*ConfigLoaderComponent) Stop

func (c *ConfigLoaderComponent) Stop()

Stop gracefully stops the component.