configloader

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("consumer", 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.