LDAP: Add API endpoint to query the LDAP server(s) status (#18868)

* LDAP: Add API endpoint to query the LDAP server(s) status|

This endpoint returns the current status(es) of the configured LDAP server(s).

The status of each server is verified by dialling and if no error is returned we assume the server is operational.

This is the last piece I'll produce as an API before moving into #18759 and see the view come to life.

pkg/services/multildap/multildap.go

@@ -28,8 +28,17 @@ var ErrNoLDAPServers = errors.New("No LDAP servers are configured")
 // ErrDidNotFindUser if request for user is unsuccessful
 var ErrDidNotFindUser = errors.New("Did not find a user")
 
+// ServerStatus holds the LDAP server status
+type ServerStatus struct {
+	Host      string
+	Port      int
+	Available bool
+	Error     error
+}
+
 // IMultiLDAP is interface for MultiLDAP
 type IMultiLDAP interface {
+	Ping() ([]*ServerStatus, error)
 	Login(query *models.LoginUserQuery) (
 		*models.ExternalUserInfo, error,
 	)
@@ -55,6 +64,39 @@ func New(configs []*ldap.ServerConfig) IMultiLDAP {
 	}
 }
 
+// Ping dials each of the LDAP servers and returns their status. If the server is unavailable, it also returns the error.
+func (multiples *MultiLDAP) Ping() ([]*ServerStatus, error) {
+
+	if len(multiples.configs) == 0 {
+		return nil, ErrNoLDAPServers
+	}
+
+	serverStatuses := []*ServerStatus{}
+	for _, config := range multiples.configs {
+
+		status := &ServerStatus{}
+
+		status.Host = config.Host
+		status.Port = config.Port
+
+		server := newLDAP(config)
+		err := server.Dial()
+
+		if err == nil {
+			status.Available = true
+			serverStatuses = append(serverStatuses, status)
+		} else {
+			status.Available = false
+			status.Error = err
+			serverStatuses = append(serverStatuses, status)
+		}
+
+		defer server.Close()
+	}
+
+	return serverStatuses, nil
+}
+
 // Login tries to log in the user in multiples LDAP
 func (multiples *MultiLDAP) Login(query *models.LoginUserQuery) (
 	*models.ExternalUserInfo, error,

pkg/services/multildap/multildap_test.go

@@ -11,6 +11,56 @@ import (
 
 func TestMultiLDAP(t *testing.T) {
 	Convey("Multildap", t, func() {
+		Convey("Ping()", func() {
+			Convey("Should return error for absent config list", func() {
+				setup()
+
+				multi := New([]*ldap.ServerConfig{})
+				_, err := multi.Ping()
+
+				So(err, ShouldBeError)
+				So(err, ShouldEqual, ErrNoLDAPServers)
+
+				teardown()
+			})
+			Convey("Should return an unavailable status on dial error", func() {
+				mock := setup()
+
+				expectedErr := errors.New("Dial error")
+				mock.dialErrReturn = expectedErr
+
+				multi := New([]*ldap.ServerConfig{
+					{Host: "10.0.0.1", Port: 361},
+				})
+
+				statuses, err := multi.Ping()
+
+				So(err, ShouldBeNil)
+				So(statuses[0].Host, ShouldEqual, "10.0.0.1")
+				So(statuses[0].Port, ShouldEqual, 361)
+				So(statuses[0].Available, ShouldBeFalse)
+				So(statuses[0].Error, ShouldEqual, expectedErr)
+
+				teardown()
+			})
+			Convey("Shoudl get the LDAP server statuses", func() {
+				setup()
+
+				multi := New([]*ldap.ServerConfig{
+					{Host: "10.0.0.1", Port: 361},
+				})
+
+				statuses, err := multi.Ping()
+
+				So(err, ShouldBeNil)
+				So(statuses[0].Host, ShouldEqual, "10.0.0.1")
+				So(statuses[0].Port, ShouldEqual, 361)
+				So(statuses[0].Available, ShouldBeTrue)
+				So(statuses[0].Error, ShouldBeNil)
+
+				teardown()
+			})
+		})
 		Convey("Login()", func() {
 			Convey("Should return error for absent config list", func() {
 				setup()

pkg/services/multildap/testing.go

@@ -69,10 +69,17 @@ type MockMultiLDAP struct {
 	LoginCalledTimes int
 	UsersCalledTimes int
 	UserCalledTimes  int
+	PingCalledTimes  int
 
 	UsersResult []*models.ExternalUserInfo
 }
 
+func (mock *MockMultiLDAP) Ping() ([]*ServerStatus, error) {
+	mock.PingCalledTimes = mock.PingCalledTimes + 1
+
+	return nil, nil
+}
+
 // Login test fn
 func (mock *MockMultiLDAP) Login(query *models.LoginUserQuery) (
 	*models.ExternalUserInfo, error,