Show cpu and memory stats of every node

services/docker.go

@@ -1,6 +1,7 @@
 package services
 
 import (
+	"io"
 	"log"
 	"strings"
 
@@ -28,6 +29,12 @@ func init() {
 
 }
 
+func GetContainerStats(id string) (io.ReadCloser, error) {
+	stats, err := c.ContainerStats(context.Background(), id, true)
+
+	return stats.Body, err
+}
+
 func GetContainerInfo(id string) (types.ContainerJSON, error) {
 	return c.ContainerInspect(context.Background(), id)
 }

services/instance.go

@@ -2,6 +2,8 @@ package services
 
 import (
 	"context"
+	"encoding/json"
+	"fmt"
 	"io"
 	"log"
 	"os"
@@ -10,17 +12,19 @@ import (
 	"golang.org/x/text/encoding"
 
 	"github.com/docker/docker/api/types"
+	units "github.com/docker/go-units"
 )
 
 var rw sync.Mutex
 
 type Instance struct {
-	session  *Session                `json:"-"`
-	Name     string                  `json:"name"`
-	Hostname string                  `json:"hostname"`
-	IP       string                  `json:"ip"`
-	conn     *types.HijackedResponse `json:"-"`
-	ctx      context.Context         `json:"-"`
+	session     *Session                `json:"-"`
+	Name        string                  `json:"name"`
+	Hostname    string                  `json:"hostname"`
+	IP          string                  `json:"ip"`
+	conn        *types.HijackedResponse `json:"-"`
+	ctx         context.Context         `json:"-"`
+	statsReader io.ReadCloser           `json:"-"`
 }
 
 func (i *Instance) IsConnected() bool {
@@ -70,6 +74,9 @@ func NewInstance(session *Session) (*Instance, error) {
 
 	wsServer.BroadcastTo(session.Id, "new instance", instance.Name, instance.IP, instance.Hostname)
 
+	// Start collecting stats
+	go instance.CollectStats()
+
 	return instance, nil
 }
 
@@ -82,6 +89,67 @@ func (s *sessionWriter) Write(p []byte) (n int, err error) {
 	return len(p), nil
 }
 
+func (o *Instance) CollectStats() {
+	reader, err := GetContainerStats(o.Hostname)
+	if err != nil {
+		log.Println("Error while trying to collect instance stats", err)
+		return
+	}
+	o.statsReader = reader
+	dec := json.NewDecoder(o.statsReader)
+	var (
+		mem          = 0.0
+		memLimit     = 0.0
+		memPercent   = 0.0
+		v            *types.StatsJSON
+		memFormatted = ""
+
+		cpuPercent     = 0.0
+		previousCPU    uint64
+		previousSystem uint64
+		cpuFormatted   = ""
+	)
+	for {
+		e := dec.Decode(&v)
+		if e != nil {
+			break
+		}
+
+		// Memory
+		if v.MemoryStats.Limit != 0 {
+			memPercent = float64(v.MemoryStats.Usage) / float64(v.MemoryStats.Limit) * 100.0
+		}
+		mem = float64(v.MemoryStats.Usage)
+		memLimit = float64(v.MemoryStats.Limit)
+
+		memFormatted = fmt.Sprintf("%.2f%% (%s / %s)", memPercent, units.BytesSize(mem), units.BytesSize(memLimit))
+
+		// cpu
+		previousCPU = v.PreCPUStats.CPUUsage.TotalUsage
+		previousSystem = v.PreCPUStats.SystemUsage
+		cpuPercent = calculateCPUPercentUnix(previousCPU, previousSystem, v)
+		cpuFormatted = fmt.Sprintf("%.2f%%", cpuPercent)
+
+		wsServer.BroadcastTo(o.session.Id, "instance stats", o.Name, memFormatted, cpuFormatted)
+	}
+
+}
+
+func calculateCPUPercentUnix(previousCPU, previousSystem uint64, v *types.StatsJSON) float64 {
+	var (
+		cpuPercent = 0.0
+		// calculate the change for the cpu usage of the container in between readings
+		cpuDelta = float64(v.CPUStats.CPUUsage.TotalUsage) - float64(previousCPU)
+		// calculate the change for the entire system between readings
+		systemDelta = float64(v.CPUStats.SystemUsage) - float64(previousSystem)
+	)
+
+	if systemDelta > 0.0 && cpuDelta > 0.0 {
+		cpuPercent = (cpuDelta / systemDelta) * float64(len(v.CPUStats.CPUUsage.PercpuUsage)) * 100.0
+	}
+	return cpuPercent
+}
+
 func (i *Instance) ResizeTerminal(cols, rows uint) error {
 	return ResizeConnection(i.Name, cols, rows)
 }
@@ -111,6 +179,11 @@ func GetInstance(session *Session, name string) *Instance {
 	return session.Instances[name]
 }
 func DeleteInstance(session *Session, instance *Instance) error {
+	// stop collecting stats
+	if instance.statsReader != nil {
+		instance.statsReader.Close()
+	}
+
 	//TODO: Use redis
 	delete(session.Instances, instance.Name)
 	err := DeleteContainer(instance.Name)

services/session.go

@@ -144,6 +144,13 @@ func LoadSessionsFromDisk() error {
 		for _, s := range sessions {
 			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
+				go i.CollectStats()
+			}
 		}
 	}
 	file.Close()