Initialization

Implement component.Initializer when a component needs setup after dependency injection.

cache.go

type CacheClient interface {
	Ping(context.Context) error
}

type Cache struct {
	client CacheClient
	ready  bool
}

func NewCache(client CacheClient) *Cache {
	return &Cache{client: client}
}

func (c *Cache) Init(ctx context.Context) error {
	if err := c.client.Ping(ctx); err != nil {
		return err
	}

	c.ready = true
	return nil
}

Use initialization for:

validating external clients
warming caches
preparing runtime state
checking required configuration

Return an error when initialization fails. Startup should fail clearly instead of leaving the component half-ready.