update micro, add Health/Live/Ready checks

Signed-off-by: Vasiliy Tolstov <v.tolstov@unistack.org>

handler/health/health.go

@@ -13,15 +13,30 @@ type Handler struct {
 	opts Options
 }
 
-type CheckFunc func(context.Context) error
+type (
+	CheckFunc func(context.Context) error
+	Option    func(*Options)
+)
 
-type Option func(*Options)
+type Stater interface {
+	Live() bool
+	Ready() bool
+	Health() bool
+}
 
 type Options struct {
-	Version     string
-	Name        string
-	LiveChecks  []CheckFunc
-	ReadyChecks []CheckFunc
+	Version      string
+	Name         string
+	Staters      []Stater
+	LiveChecks   []CheckFunc
+	ReadyChecks  []CheckFunc
+	HealthChecks []CheckFunc
+}
+
+func Service(s ...Stater) Option {
+	return func(o *Options) {
+		o.Staters = append(o.Staters, s...)
+	}
 }
 
 func LiveChecks(fns ...CheckFunc) Option {
@@ -36,6 +51,12 @@ func ReadyChecks(fns ...CheckFunc) Option {
 	}
 }
 
+func HealthChecks(fns ...CheckFunc) Option {
+	return func(o *Options) {
+		o.HealthChecks = append(o.HealthChecks, fns...)
+	}
+}
+
 func Name(name string) Option {
 	return func(o *Options) {
 		o.Name = name
@@ -56,18 +77,51 @@ func NewHandler(opts ...Option) *Handler {
 	return &Handler{opts: options}
 }
 
+func (h *Handler) Healthy(ctx context.Context, req *codecpb.Frame, rsp *codecpb.Frame) error {
+	var err error
+
+	for _, s := range h.opts.Staters {
+		if !s.Health() {
+			return errors.ServiceUnavailable(h.opts.Name, "%v", err)
+		}
+	}
+
+	for _, fn := range h.opts.HealthChecks {
+		if err = fn(ctx); err != nil {
+			return errors.ServiceUnavailable(h.opts.Name, "%v", err)
+		}
+	}
+
+	return nil
+}
+
 func (h *Handler) Live(ctx context.Context, req *codecpb.Frame, rsp *codecpb.Frame) error {
 	var err error
+
+	for _, s := range h.opts.Staters {
+		if !s.Live() {
+			return errors.ServiceUnavailable(h.opts.Name, "%v", err)
+		}
+	}
+
 	for _, fn := range h.opts.LiveChecks {
 		if err = fn(ctx); err != nil {
 			return errors.ServiceUnavailable(h.opts.Name, "%v", err)
 		}
 	}
+
 	return nil
 }
 
 func (h *Handler) Ready(ctx context.Context, req *codecpb.Frame, rsp *codecpb.Frame) error {
 	var err error
+
+	for _, s := range h.opts.Staters {
+		if !s.Ready() {
+			return errors.ServiceUnavailable(h.opts.Name, "%v", err)
+		}
+	}
+
 	for _, fn := range h.opts.ReadyChecks {
 		if err = fn(ctx); err != nil {
 			return errors.ServiceUnavailable(h.opts.Name, "%v", err)