discovery

type Instance interface {
	Address() net.Addr
	Weight() int
	Tag(key string) (value string, exist bool)
}

type Resolver interface {
	// Target should return a description for the given target that is suitable for being a key for cache.
	Target(ctx context.Context, target *TargetInfo) string

	// Resolve returns a list of instances for the given description of a target.
	Resolve(ctx context.Context, desc string) (Result, error)

	// Name returns the name of the resolver.
	Name() string
}

type Result struct {
	CacheKey  string
	Instances []Instance
}

type SynthesizedResolver struct {
	TargetFunc  func(ctx context.Context, target *TargetInfo) string
	ResolveFunc func(ctx context.Context, key string) (Result, error)
	NameFunc    func() string
}

type TargetInfo struct {
	Host string
	Tags map[string]string
}