Commit d3360299 authored by Matthew Sykes's avatar Matthew Sykes
Browse files

Wire the health check handler into operations

FAB-12717 #done
FAB-12720 #done

Change-Id: I29da1e50a46edf7e889c12709012cdcb63f949ef
Signed-off-by: default avatarMatthew Sykes <>
parent db46110c
......@@ -350,6 +350,14 @@
pruneopts = "NUT"
revision = "6b78f7a22d950103fb2669aabb969f56d42d283b"
branch = "master"
digest = "1:0f4305e5a43e324844412168385a23ff23dafc55369fcbbc2ea77fb974f828cc"
name = ""
packages = ["healthz"]
pruneopts = "NUT"
revision = "90dc96fb23ab7eb18477e4bfcf9cd8ebdb7209f0"
digest = "1:406338ad39ab2e37b7f4452906442a3dbf0eb3379dd1f06aafb5c07e769a5fbb"
name = ""
......@@ -943,6 +951,7 @@
......@@ -57,6 +57,10 @@ noverify = [
branch = "master"
name = ""
branch = "master"
name = ""
branch = "master"
name = ""
// Code generated by counterfeiter. DO NOT EDIT.
package fakes
import (
context "context"
sync "sync"
type HealthChecker struct {
HealthCheckStub func(context.Context) error
healthCheckMutex sync.RWMutex
healthCheckArgsForCall []struct {
arg1 context.Context
healthCheckReturns struct {
result1 error
healthCheckReturnsOnCall map[int]struct {
result1 error
invocations map[string][][]interface{}
invocationsMutex sync.RWMutex
func (fake *HealthChecker) HealthCheck(arg1 context.Context) error {
ret, specificReturn := fake.healthCheckReturnsOnCall[len(fake.healthCheckArgsForCall)]
fake.healthCheckArgsForCall = append(fake.healthCheckArgsForCall, struct {
arg1 context.Context
fake.recordInvocation("HealthCheck", []interface{}{arg1})
if fake.HealthCheckStub != nil {
return fake.HealthCheckStub(arg1)
if specificReturn {
return ret.result1
fakeReturns := fake.healthCheckReturns
return fakeReturns.result1
func (fake *HealthChecker) HealthCheckCallCount() int {
defer fake.healthCheckMutex.RUnlock()
return len(fake.healthCheckArgsForCall)
func (fake *HealthChecker) HealthCheckCalls(stub func(context.Context) error) {
defer fake.healthCheckMutex.Unlock()
fake.HealthCheckStub = stub
func (fake *HealthChecker) HealthCheckArgsForCall(i int) context.Context {
defer fake.healthCheckMutex.RUnlock()
argsForCall := fake.healthCheckArgsForCall[i]
return argsForCall.arg1
func (fake *HealthChecker) HealthCheckReturns(result1 error) {
defer fake.healthCheckMutex.Unlock()
fake.HealthCheckStub = nil
fake.healthCheckReturns = struct {
result1 error
func (fake *HealthChecker) HealthCheckReturnsOnCall(i int, result1 error) {
defer fake.healthCheckMutex.Unlock()
fake.HealthCheckStub = nil
if fake.healthCheckReturnsOnCall == nil {
fake.healthCheckReturnsOnCall = make(map[int]struct {
result1 error
fake.healthCheckReturnsOnCall[i] = struct {
result1 error
func (fake *HealthChecker) Invocations() map[string][][]interface{} {
defer fake.invocationsMutex.RUnlock()
defer fake.healthCheckMutex.RUnlock()
copiedInvocations := map[string][][]interface{}{}
for key, value := range fake.invocations {
copiedInvocations[key] = value
return copiedInvocations
func (fake *HealthChecker) recordInvocation(key string, args []interface{}) {
defer fake.invocationsMutex.Unlock()
if fake.invocations == nil {
fake.invocations = map[string][][]interface{}{}
if fake.invocations[key] == nil {
fake.invocations[key] = [][]interface{}{}
fake.invocations[key] = append(fake.invocations[key], args)
......@@ -14,6 +14,7 @@ import (
. ""
. ""
......@@ -69,3 +70,8 @@ func newHTTPClient(tlsDir string) *http.Client {
//go:generate counterfeiter -o fakes/healthchecker.go -fake-name HealthChecker . healthChecker
type healthChecker interface {
......@@ -16,6 +16,7 @@ import (
kitstatsd ""
......@@ -63,6 +64,7 @@ type System struct {
logger Logger
healthHandler *healthz.HealthHandler
options Options
statsd *kitstatsd.Statsd
collectorTicker *time.Ticker
......@@ -84,6 +86,7 @@ func NewSystem(o Options) *System {
......@@ -135,6 +138,10 @@ func (s *System) Stop() error {
return s.httpServer.Shutdown(ctx)
func (s *System) RegisterChecker(component string, checker healthz.HealthChecker) error {
return s.healthHandler.RegisterChecker(component, checker)
func (s *System) initializeServer() {
s.mux = http.NewServeMux()
s.httpServer = &http.Server{
......@@ -188,6 +195,11 @@ func (s *System) initializeLoggingHandler() {
s.mux.Handle("/logspec", s.handlerChain(httpadmin.NewSpecHandler(), secure))
func (s *System) initializeHealthCheckHandler() {
s.healthHandler = healthz.NewHealthHandler()
s.mux.Handle("/healthz", s.handlerChain(s.healthHandler, false))
func (s *System) startMetricsTickers() error {
m := s.options.Metrics
if s.statsd != nil {
......@@ -7,6 +7,8 @@ SPDX-License-Identifier: Apache-2.0
package operations_test
import (
......@@ -17,6 +19,7 @@ import (
......@@ -158,6 +161,34 @@ var _ = Describe("System", func() {
It("hosts a health check endpoint", func() {
err := system.Start()
healthy := &fakes.HealthChecker{}
unhealthy := &fakes.HealthChecker{}
unhealthy.HealthCheckReturns(errors.New("Unfortunately, I am not feeling well."))
system.RegisterChecker("healthy", healthy)
system.RegisterChecker("unhealthy", unhealthy)
resp, err := client.Get(fmt.Sprintf("https://%s/healthz", system.Addr()))
body, err := ioutil.ReadAll(resp.Body)
var healthStatus healthz.HealthStatus
err = json.Unmarshal(body, &healthStatus)
Component: "unhealthy",
Reason: "Unfortunately, I am not feeling well.",
Context("when the metrics provider is disabled", func() {
BeforeEach(func() {
options.Metrics = operations.MetricsOptions{
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SPDX-License-Identifier: Apache-2.0
// Package healthz provides an HTTP handler which returns the health status of
// one or more components of an application or service.
package healthz
import (
type AlreadyRegisteredError string
func (are AlreadyRegisteredError) Error() string {
return fmt.Sprintf("'%s' is already registered", are)
const (
// StatusOK is returned if all health checks pass.
StatusOK = "OK"
// StatusUnavailable is returned if any health check fails.
StatusUnavailable = "Service Unavailable"
//go:generate counterfeiter -o mock/health_checker.go -fake-name HealthChecker . HealthChecker
// HealthChecker defines the interface components must implement in order to
// register with the Handler in order to be included in the health status.
// HealthCheck is passed a context with a Done channel which is closed due to
// a timeout or cancellation.
type HealthChecker interface {
HealthCheck(context.Context) error
// FailedCheck represents a failed status check for a component.
type FailedCheck struct {
Component string `json:"component"`
Reason string `json:"reason"`
// HealthStatus represents the current health status of all registered components.
type HealthStatus struct {
Status string `json:"status"`
Time time.Time `json:"time"`
FailedChecks []FailedCheck `json:"failed_checks,omitempty"`
// NewHealthHandler returns a new HealthHandler instance.
func NewHealthHandler() *HealthHandler {
return &HealthHandler{
healthCheckers: map[string]HealthChecker{},
now: time.Now,
timeout: 30 * time.Second,
// HealthHandler is responsible for executing registered health checks. It
// provides an HTTP handler which returns the health status for all registered
// components.
type HealthHandler struct {
mutex sync.RWMutex
healthCheckers map[string]HealthChecker
now func() time.Time
timeout time.Duration
// RegisterChecker registers a HealthChecker for a named component and adds it to
// the list of status checks to run. It returns an error if the component has
// already been registered.
func (h *HealthHandler) RegisterChecker(component string, checker HealthChecker) error {
defer h.mutex.Unlock()
if _, ok := h.healthCheckers[component]; ok {
return AlreadyRegisteredError(component)
h.healthCheckers[component] = checker
return nil
// DeregisterChecker deregisters a named HealthChecker.
func (h *HealthHandler) DeregisterChecker(component string) {
defer h.mutex.Unlock()
delete(h.healthCheckers, component)
// SetTimeout sets the timeout for handling HTTP requests. If not explicitly
// set, defaults to 30 seconds.
func (h *HealthHandler) SetTimeout(timeout time.Duration) {
h.timeout = timeout
// ServerHTTP is an HTTP handler (see http.Handler) which can be used as
// an HTTP endpoint for health checks. If all registered checks pass, it returns
// an HTTP status `200 OK` with a JSON payload of `{"status": "OK"}`. If all
// checks do not pass, it returns an HTTP status `503 Service Unavailable` with
// a JSON payload of `{"status": "Service Unavailable","failed_checks":[...]}.
func (h *HealthHandler) ServeHTTP(rw http.ResponseWriter, req *http.Request) {
if req.Method != "GET" {
checksCtx, cancel := context.WithTimeout(req.Context(), h.timeout)
defer cancel()
failedCheckCh := make(chan []FailedCheck)
go func() {
failedCheckCh <- h.RunChecks(checksCtx)
select {
case failedChecks := <-failedCheckCh:
hs := HealthStatus{
Status: StatusOK,
if len(failedChecks) > 0 {
hs.Status = StatusUnavailable
hs.FailedChecks = failedChecks
writeHTTPResponse(rw, hs)
case <-checksCtx.Done():
if checksCtx.Err() == context.DeadlineExceeded {
// RunChecks runs all healthCheckers and returns any failures.
func (h *HealthHandler) RunChecks(ctx context.Context) []FailedCheck {
defer h.mutex.RUnlock()
var failedChecks []FailedCheck
for component, checker := range h.healthCheckers {
if err := checker.HealthCheck(ctx); err != nil {
failedCheck := FailedCheck{
Component: component,
Reason: err.Error(),
failedChecks = append(failedChecks, failedCheck)