Correctly send stats & proc information back for servers

environment/docker/container.go

@@ -47,19 +47,27 @@ func (e *Environment) Attach() error {
 		e.SetStream(&st)
 	}
 
-	console := new(Console)
+	c := new(Console)
+	go func(console *Console) {
+		ctx, cancel := context.WithCancel(context.Background())
 
-	// TODO: resource polling should be handled by the server itself and just call a function
-	//  on the environment that can return the data. Same for disabling polling.
-	go func() {
+		defer cancel()
 		defer e.stream.Close()
 		defer func() {
 			e.setState(system.ProcessOfflineState)
 			e.SetStream(nil)
 		}()
 
+		// Poll resources in a seperate thread since this will block the copy call below
+		// from being reached until it is completed if not run in a seperate process. However,
+		// we still want it to be stopped when the copy operation below is finished running which
+		// indicates that the container is no longer running.
+		go e.pollResources(ctx)
+
+		// Stream the reader output to the console which will then fire off events and handle console
+		// throttling and sending the output to the user.
 		_, _ = io.Copy(console, e.stream.Reader)
-	}()
+	}(c)
 
 	return nil
 }

environment/docker/stats.go

@@ -0,0 +1,120 @@
+package docker
+
+import (
+	"context"
+	"encoding/json"
+	"github.com/apex/log"
+	"github.com/docker/docker/api/types"
+	"github.com/pkg/errors"
+	"github.com/pterodactyl/wings/environment"
+	"github.com/pterodactyl/wings/system"
+	"io"
+	"math"
+	"sync/atomic"
+)
+
+// Attach to the instance and then automatically emit an event whenever the resource usage for the
+// server process changes.
+func (e *Environment) pollResources(ctx context.Context) error {
+	if e.State() == system.ProcessOfflineState {
+		return errors.New("attempting to enable resource polling on a stopped server instance")
+	}
+
+	stats, err := e.client.ContainerStats(context.Background(), e.Id, true)
+	if err != nil {
+		return errors.WithStack(err)
+	}
+
+	dec := json.NewDecoder(stats.Body)
+
+	for {
+		select {
+		case <-ctx.Done():
+			return ctx.Err()
+		default:
+			var v *types.StatsJSON
+
+			if err := dec.Decode(&v); err != nil {
+				if err != io.EOF {
+					log.WithField("container_id", e.Id).Warn("encountered error processing docker stats output, stopping collection")
+				}
+
+				return nil
+			}
+
+			// Disable collection if the server is in an offline state and this process is still running.
+			if e.State() == system.ProcessOfflineState {
+				return nil
+			}
+
+			var rx uint64
+			var tx uint64
+			for _, nw := range v.Networks {
+				atomic.AddUint64(&rx, nw.RxBytes)
+				atomic.AddUint64(&tx, nw.RxBytes)
+			}
+
+			st := &environment.Stats{
+				Memory:      calculateDockerMemory(v.MemoryStats),
+				MemoryLimit: v.MemoryStats.Limit,
+				CpuAbsolute: calculateDockerAbsoluteCpu(&v.PreCPUStats, &v.CPUStats),
+				Network: struct {
+					RxBytes uint64 `json:"rx_bytes"`
+					TxBytes uint64 `json:"tx_bytes"`
+				}{
+					RxBytes: rx,
+					TxBytes: tx,
+				},
+			}
+
+			b, _ := json.Marshal(st)
+			e.Events().Publish(environment.ResourceEvent, string(b))
+		}
+	}
+}
+
+// The "docker stats" CLI call does not return the same value as the types.MemoryStats.Usage
+// value which can be rather confusing to people trying to compare panel usage to
+// their stats output.
+//
+// This math is straight up lifted from their CLI repository in order to show the same
+// values to avoid people bothering me about it. It should also reflect a slightly more
+// correct memory value anyways.
+//
+// @see https://github.com/docker/cli/blob/96e1d1d6/cli/command/container/stats_helpers.go#L227-L249
+func calculateDockerMemory(stats types.MemoryStats) uint64 {
+	if v, ok := stats.Stats["total_inactive_file"]; ok && v < stats.Usage {
+		return stats.Usage - v
+	}
+
+	if v := stats.Stats["inactive_file"]; v < stats.Usage {
+		return stats.Usage - v
+	}
+
+	return stats.Usage
+}
+
+// Calculates the absolute CPU usage used by the server process on the system, not constrained
+// by the defined CPU limits on the container.
+//
+// @see https://github.com/docker/cli/blob/aa097cf1aa19099da70930460250797c8920b709/cli/command/container/stats_helpers.go#L166
+func calculateDockerAbsoluteCpu(pStats *types.CPUStats, stats *types.CPUStats) float64 {
+	// Calculate the change in CPU usage between the current and previous reading.
+	cpuDelta := float64(stats.CPUUsage.TotalUsage) - float64(pStats.CPUUsage.TotalUsage)
+
+	// Calculate the change for the entire system's CPU usage between current and previous reading.
+	systemDelta := float64(stats.SystemUsage) - float64(pStats.SystemUsage)
+
+	// Calculate the total number of CPU cores being used.
+	cpus := float64(stats.OnlineCPUs)
+	if cpus == 0.0 {
+		cpus = float64(len(stats.CPUUsage.PercpuUsage))
+	}
+
+	percent := 0.0
+	if systemDelta > 0.0 && cpuDelta > 0.0 {
+		percent = (cpuDelta / systemDelta) * cpus * 100.0
+	}
+
+	return math.Round(percent*1000) / 1000
+}