add health check to ensure default subnet is bootstrapped. add monotonicHealthCheck type

api/health/checks.go

@@ -63,6 +63,24 @@ func (c check) InitialDelay() time.Duration { return c.initialDelay }
 // InitiallyPassing is whether or not to consider the Check healthy before the initial execution
 func (c check) InitiallyPassing() bool { return c.initiallyPassing }
 
+// monotonicCheck is a check that will run until it passes once, and after that it will
+// always pass without performing any logic. Used for bootstrapping, for example.
+type monotonicCheck struct {
+	passed bool
+	check
+}
+
+func (mc monotonicCheck) Execute() (interface{}, error) {
+	if mc.passed {
+		return nil, nil
+	}
+	details, pass := mc.Execute()
+	if pass == nil {
+		mc.passed = true
+	}
+	return details, pass
+}
+
 // Heartbeater provides a getter to the most recently observed heartbeat
 type Heartbeater interface {
 	GetHeartbeat() int64

api/health/service.go

@@ -66,6 +66,15 @@ func (h *Health) RegisterCheckFunc(name string, checkFn CheckFn) error {
 	return h.RegisterCheck(check)
 }
 
+// RegisterMonotonicCheckFunc adds a Check with default options and the given CheckFn
+// After it passes once, its logic (checkFunc) is never run again; it just passes
+func (h *Health) RegisterMonotonicCheckFunc(name string, checkFn CheckFn) error {
+	check := monotonicCheck{check: defaultCheckOpts}
+	check.name = name
+	check.checkFn = checkFn
+	return h.RegisterCheck(check)
+}
+
 // RegisterCheck adds the given Check
 func (h *Health) RegisterCheck(c Check) error {
 	return h.health.RegisterCheck(&health.Config{

node/node.go

@@ -7,6 +7,7 @@ import (
 	"crypto/tls"
 	"crypto/x509"
 	"encoding/pem"
+	"errors"
 	"fmt"
 	"io/ioutil"
 	"net"
@@ -507,6 +508,30 @@ func (n *Node) initHealthAPI() error {
 	n.Log.Info("initializing Health API")
 	service := health.NewService(n.Log)
 	service.RegisterHeartbeat("network.validators.heartbeat", n.Net, 5*time.Minute)
+	isBootstrappedFunc := func() (interface{}, error) {
+		pChainID, err := n.chainManager.Lookup("P")
+		if err != nil {
+			return nil, errors.New("P-Chain not created")
+		} else if !n.chainManager.IsBootstrapped(pChainID) {
+			return nil, errors.New("P-Chain not bootstrapped")
+		}
+		xChainID, err := n.chainManager.Lookup("X")
+		if err != nil {
+			return nil, errors.New("X-Chain not created")
+		} else if !n.chainManager.IsBootstrapped(xChainID) {
+			return nil, errors.New("X-Chain not bootstrapped")
+		}
+		cChainID, err := n.chainManager.Lookup("C")
+		if err != nil {
+			return nil, errors.New("C-Chain not created")
+		} else if !n.chainManager.IsBootstrapped(cChainID) {
+			return nil, errors.New("C-Chain not bootstrapped")
+		}
+		return nil, nil
+	}
+	if err := service.RegisterMonotonicCheckFunc("defaultChainsBootstrapped", isBootstrappedFunc); err != nil {
+		return err
+	}
 	return n.APIServer.AddRoute(service.Handler(), &sync.RWMutex{}, "health", "", n.HTTPLog)
 }