AUTH-2588 add DoH to service mode

overwatch/app_manager.go

@@ -0,0 +1,53 @@
+package overwatch
+
+// AppManager is the default implementation of overwatch service management
+type AppManager struct {
+	services  map[string]Service
+	errorChan chan error
+}
+
+// NewAppManager creates a new overwatch manager
+func NewAppManager(errorChan chan error) Manager {
+	return &AppManager{services: make(map[string]Service), errorChan: errorChan}
+}
+
+// Add takes in a new service to manage.
+// It stops the service if it already exist in the manager and is running
+// It then starts the newly added service
+func (m *AppManager) Add(service Service) {
+	// check for existing service
+	if currentService, ok := m.services[service.Name()]; ok {
+		if currentService.Hash() == service.Hash() {
+			return // the exact same service, no changes, so move along
+		}
+		currentService.Shutdown() //shutdown the listener since a new one is starting
+	}
+	m.services[service.Name()] = service
+
+	//start the service!
+	go m.serviceRun(service)
+}
+
+// Remove shutdowns the service by name and removes it from its current management list
+func (m *AppManager) Remove(name string) {
+	if currentService, ok := m.services[name]; ok {
+		currentService.Shutdown()
+	}
+	delete(m.services, name)
+}
+
+// Services returns all the current Services being managed
+func (m *AppManager) Services() []Service {
+	values := []Service{}
+	for _, value := range m.services {
+		values = append(values, value)
+	}
+	return values
+}
+
+func (m *AppManager) serviceRun(service Service) {
+	err := service.Run()
+	if err != nil && m.errorChan != nil {
+		m.errorChan <- err
+	}
+}

overwatch/manager.go

@@ -0,0 +1,17 @@
+package overwatch
+
+// Service is the required functions for an object to be managed by the overwatch Manager
+type Service interface {
+	Name() string
+	Type() string
+	Hash() string
+	Shutdown()
+	Run() error
+}
+
+// Manager is based type to manage running services
+type Manager interface {
+	Add(Service)
+	Remove(string)
+	Services() []Service
+}

overwatch/manager_test.go

@@ -0,0 +1,74 @@
+package overwatch
+
+import (
+	"crypto/md5"
+	"errors"
+	"fmt"
+	"io"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+type mockService struct {
+	serviceName string
+	serviceType string
+	runError    error
+}
+
+func (s *mockService) Name() string {
+	return s.serviceName
+}
+
+func (s *mockService) Type() string {
+	return s.serviceType
+}
+
+func (s *mockService) Hash() string {
+	h := md5.New()
+	io.WriteString(h, s.serviceName)
+	io.WriteString(h, s.serviceType)
+	return fmt.Sprintf("%x", h.Sum(nil))
+}
+
+func (s *mockService) Shutdown() {
+}
+
+func (s *mockService) Run() error {
+	return s.runError
+}
+
+func TestManagerAddAndRemove(t *testing.T) {
+	m := NewAppManager(nil)
+
+	first := &mockService{serviceName: "first", serviceType: "mock"}
+	second := &mockService{serviceName: "second", serviceType: "mock"}
+	m.Add(first)
+	m.Add(second)
+	assert.Len(t, m.Services(), 2, "expected 2 services in the list")
+
+	m.Remove(first.Name())
+	services := m.Services()
+	assert.Len(t, services, 1, "expected 1 service in the list")
+	assert.Equal(t, second.Hash(), services[0].Hash(), "hashes should match. Wrong service was removed")
+}
+
+func TestManagerDuplicate(t *testing.T) {
+	m := NewAppManager(nil)
+
+	first := &mockService{serviceName: "first", serviceType: "mock"}
+	m.Add(first)
+	m.Add(first)
+	assert.Len(t, m.Services(), 1, "expected 1 service in the list")
+}
+
+func TestManagerErrorChannel(t *testing.T) {
+	errChan := make(chan error)
+	m := NewAppManager(errChan)
+
+	err := errors.New("test error")
+	first := &mockService{serviceName: "first", serviceType: "mock", runError: err}
+	m.Add(first)
+	respErr := <-errChan
+	assert.Equal(t, err, respErr, "errors don't match")
+}