docker-labs/services/session.go

package services

import (
	"encoding/gob"
	"fmt"
	"log"
	"math"
	"net"
	"net/http"
	"os"
	"strconv"
	"sync"
	"time"

	"github.com/docker/docker/client"
	"github.com/googollee/go-socket.io"
	"github.com/prometheus/client_golang/prometheus"
	"github.com/twinj/uuid"
)

var (
	sessionsGauge = prometheus.NewGauge(prometheus.GaugeOpts{
		Name: "sessions",
		Help: "Sessions",
	})
)

func init() {
	prometheus.MustRegister(sessionsGauge)
}

var wsServer *socketio.Server

type Session struct {
	rw        sync.Mutex
	Id        string               `json:"id"`
	Instances map[string]*Instance `json:"instances"`
	clients   []*Client            `json:"-"`
	CreatedAt time.Time            `json:"created_at"`
	ExpiresAt time.Time            `json:"expires_at"`
	scheduled bool                 `json:"-"`
	ticker    *time.Ticker         `json:"-"`
}

func (s *Session) Lock() {
	s.rw.Lock()
}

func (s *Session) Unlock() {
	s.rw.Unlock()
}

func (s *Session) GetSmallestViewPort() ViewPort {
	minRows := s.clients[0].ViewPort.Rows
	minCols := s.clients[0].ViewPort.Cols

	for _, c := range s.clients {
		minRows = uint(math.Min(float64(minRows), float64(c.ViewPort.Rows)))
		minCols = uint(math.Min(float64(minCols), float64(c.ViewPort.Cols)))
	}

	return ViewPort{Rows: minRows, Cols: minCols}
}

func (s *Session) AddNewClient(c *Client) {
	s.clients = append(s.clients, c)
}

func (s *Session) SchedulePeriodicTasks() {
	if s.scheduled {
		return
	}

	go func() {
		s.scheduled = true

		s.ticker = time.NewTicker(1 * time.Second)
		for range s.ticker.C {
			var wg = sync.WaitGroup{}
			wg.Add(len(s.Instances))
			for _, ins := range s.Instances {
				var i *Instance = ins
				if i.dockerClient == nil {
					// Need to create client to the DinD docker daemon

					transport := &http.Transport{
						DialContext: (&net.Dialer{
							Timeout:   1 * time.Second,
							KeepAlive: 30 * time.Second,
						}).DialContext}
					cli := &http.Client{
						Transport: transport,
					}
					c, err := client.NewClient(fmt.Sprintf("http://%s:2375", i.IP), client.DefaultVersion, cli, nil)
					if err != nil {
						log.Println("Could not connect to DinD docker daemon", err)
					} else {
						i.dockerClient = c
					}
				}
				go func() {
					defer wg.Done()
					for _, t := range periodicTasks {
						t.Run(i)
					}
				}()
			}
			wg.Wait()
			// broadcast all information
			for _, ins := range s.Instances {
				ins.Ports = ins.tempPorts
				ins.tempPorts = []uint16{}
				wsServer.BroadcastTo(ins.session.Id, "instance stats", ins.Name, ins.Mem, ins.Cpu, ins.IsManager, ins.Ports)
			}
		}
	}()
}

var sessions map[string]*Session

func init() {
	sessions = make(map[string]*Session)
}

func CreateWSServer() *socketio.Server {
	server, err := socketio.NewServer(nil)
	if err != nil {
		log.Fatal(err)
	}
	wsServer = server
	return server
}

func CloseSessionAfter(s *Session, d time.Duration) {
	time.AfterFunc(d, func() {
		CloseSession(s)
	})
}

func CloseSession(s *Session) error {
	s.rw.Lock()
	defer s.rw.Unlock()

	sessionsGauge.Dec()
	if s.ticker != nil {
		s.ticker.Stop()
	}
	wsServer.BroadcastTo(s.Id, "session end")
	for _, c := range s.clients {
		c.so.Emit("disconnect")
		clientsGauge.Dec()
	}
	log.Printf("Starting clean up of session [%s]\n", s.Id)
	for _, i := range s.Instances {
		if i.conn != nil {
			i.conn.Close()
		}
		if err := DeleteContainer(i.Name); err != nil {
			log.Println(err)
			return err
		}
	}
	if err := DeleteNetwork(s.Id); err != nil {
		log.Println(err)
		return err
	}
	delete(sessions, s.Id)

	// We store sessions as soon as we delete one
	if err := saveSessionsToDisk(); err != nil {
		return err
	}
	log.Printf("Cleaned up session [%s]\n", s.Id)
	return nil
}

// Todo: this handles minimum viable product and removes hard-coding of hours value :)
// For future enhance to return time.Duration and parse a string / flag.
func getExpiryHours() int {
	hours := 4
	override := os.Getenv("EXPIRY")
	if len(override) > 0 {
		value, err := strconv.Atoi(override)
		if err == nil {
			hours = value
		}
	}
	return hours
}

func NewSession() (*Session, error) {
	hours := getExpiryHours()
	duration := time.Duration(hours) * time.Hour

	s := &Session{}
	s.Id = uuid.NewV4().String()
	s.Instances = map[string]*Instance{}
	s.CreatedAt = time.Now()
	s.ExpiresAt = s.CreatedAt.Add(duration)
	log.Printf("NewSession id=[%s]\n", s.Id)

	sessions[s.Id] = s

	// Schedule cleanup of the session
	CloseSessionAfter(s, duration)

	if err := CreateNetwork(s.Id); err != nil {
		log.Println("ERROR NETWORKING")
		return nil, err
	}
	log.Printf("Network [%s] created for session [%s]\n", s.Id, s.Id)

	// Connect PWD daemon to the new network
	if err := ConnectNetwork("pwd", s.Id); err != nil {
		log.Println("ERROR NETWORKING")
		return nil, err
	}
	log.Printf("Connected pwd to network [%s]\n", s.Id)

	// Schedule peridic tasks execution
	s.SchedulePeriodicTasks()

	// We store sessions as soon as we create one so we don't delete new sessions on an api restart
	if err := saveSessionsToDisk(); err != nil {
		return nil, err
	}

	sessionsGauge.Inc()
	return s, nil
}

func GetSession(sessionId string) *Session {
	s := sessions[sessionId]
	if s != nil {
		for _, instance := range s.Instances {
			if !instance.IsConnected() {
				instance.SetSession(s)
				go instance.Attach()
			}
		}

	}
	return s
}

func LoadSessionsFromDisk() error {
	file, err := os.Open("./pwd/sessions.gob")
	if err == nil {
		decoder := gob.NewDecoder(file)
		err = decoder.Decode(&sessions)

		if err != nil {
			return err
		}

		// schedule session expiration
		for _, s := range sessions {
			sessionsGauge.Inc()
			timeLeft := s.ExpiresAt.Sub(time.Now())
			CloseSessionAfter(s, timeLeft)

			// start collecting stats for every instance
			for _, i := range s.Instances {
				// wire the session back to the instance
				i.session = s
				instancesGauge.Inc()
			}

			// Connect PWD daemon to the new network
			if err := ConnectNetwork("pwd", s.Id); err != nil {
				log.Println("ERROR NETWORKING")
				return err
			}
			log.Printf("Connected pwd to network [%s]\n", s.Id)

			// Schedule peridic tasks execution
			s.SchedulePeriodicTasks()
		}
	}
	file.Close()
	return err
}

func saveSessionsToDisk() error {
	rw.Lock()
	defer rw.Unlock()
	file, err := os.Create("./pwd/sessions.gob")
	if err == nil {
		encoder := gob.NewEncoder(file)
		err = encoder.Encode(&sessions)
	}
	file.Close()
	return err
}