Small refactoring of docker manager

- Add isWindows flag to dockerManager
- `CalculateCpuPercentWindows` and `CalculateCpuPercentLinux` methods added to container.ApiStats
- Remove prevNetStats.Time in favor of Stats.PrevRead
- Replace regex Windows check with strings.Contains, and check the `/containers/json` response

beszel/internal/agent/docker.go

@@ -26,6 +26,7 @@ type dockerManager struct {
 	containerStatsMap   map[string]*container.Stats // Keeps track of container stats
 	validIds            map[string]struct{}         // Map of valid container ids, used to prune invalid containers from containerStatsMap
 	goodDockerVersion   bool                        // Whether docker version is at least 25.0.0 (one-shot works correctly)
+	isWindows           bool                        // Whether the Docker Engine API is running on Windows
 }
 
 // userAgentRoundTripper is a custom http.RoundTripper that adds a User-Agent header to all requests
@@ -69,6 +70,8 @@ func (dm *dockerManager) getDockerStats() ([]*container.Stats, error) {
 		return nil, err
 	}
 
+	dm.isWindows = strings.Contains(resp.Header.Get("Server"), "windows")
+
 	containersLength := len(dm.apiContainerList)
 
 	// store valid ids to clean up old container ids from map
@@ -80,8 +83,7 @@ func (dm *dockerManager) getDockerStats() ([]*container.Stats, error) {
 
 	var failedContainers []*container.ApiInfo
 
-	for i := range dm.apiContainerList {
-		ctr := dm.apiContainerList[i]
+	for _, ctr := range dm.apiContainerList {
 		ctr.IdShort = ctr.Id[:12]
 		dm.validIds[ctr.IdShort] = struct{}{}
 		// check if container is less than 1 minute old (possible restart)
@@ -167,22 +169,27 @@ func (dm *dockerManager) updateContainerStats(ctr *container.ApiInfo) error {
 		return err
 	}
 
-	// check if container has valid data, otherwise may be in restart loop (#103)
-	if res.MemoryStats.Usage == 0 {
-		return fmt.Errorf("%s - no memory stats - see https://github.com/henrygd/beszel/issues/144", name)
+	// calculate cpu and memory stats
+	var usedMemory uint64
+	var cpuPct float64
+
+	if dm.isWindows {
+		usedMemory = res.MemoryStats.PrivateWorkingSet
+		cpuPct = res.CalculateCpuPercentWindows(stats.PrevCpu[0], stats.PrevRead)
+	} else {
+		// check if container has valid data, otherwise may be in restart loop (#103)
+		if res.MemoryStats.Usage == 0 {
+			return fmt.Errorf("%s - no memory stats - see https://github.com/henrygd/beszel/issues/144", name)
+		}
+		memCache := res.MemoryStats.Stats.InactiveFile
+		if memCache == 0 {
+			memCache = res.MemoryStats.Stats.Cache
+		}
+		usedMemory = res.MemoryStats.Usage - memCache
+
+		cpuPct = res.CalculateCpuPercentLinux(stats.PrevCpu)
 	}
 
-	// memory (https://docs.docker.com/reference/cli/docker/container/stats/)
-	memCache := res.MemoryStats.Stats.InactiveFile
-	if memCache == 0 {
-		memCache = res.MemoryStats.Stats.Cache
-	}
-	usedMemory := res.MemoryStats.Usage - memCache
-
-	// cpu
-	cpuDelta := res.CPUStats.CPUUsage.TotalUsage - stats.PrevCpu[0]
-	systemDelta := res.CPUStats.SystemUsage - stats.PrevCpu[1]
-	cpuPct := float64(cpuDelta) / float64(systemDelta) * 100
 	if cpuPct > 100 {
 		return fmt.Errorf("%s cpu pct greater than 100: %+v", name, cpuPct)
 	}
@@ -197,18 +204,18 @@ func (dm *dockerManager) updateContainerStats(ctr *container.ApiInfo) error {
 	var sent_delta, recv_delta float64
 	// prevent first run from sending all prev sent/recv bytes
 	if initialized {
-		secondsElapsed := time.Since(stats.PrevNet.Time).Seconds()
+		secondsElapsed := time.Since(stats.PrevRead).Seconds()
 		sent_delta = float64(total_sent-stats.PrevNet.Sent) / secondsElapsed
 		recv_delta = float64(total_recv-stats.PrevNet.Recv) / secondsElapsed
 	}
 	stats.PrevNet.Sent = total_sent
 	stats.PrevNet.Recv = total_recv
-	stats.PrevNet.Time = time.Now()
 
 	stats.Cpu = twoDecimals(cpuPct)
 	stats.Mem = bytesToMegabytes(float64(usedMemory))
 	stats.NetworkSent = bytesToMegabytes(sent_delta)
 	stats.NetworkRecv = bytesToMegabytes(recv_delta)
+	stats.PrevRead = res.Read
 
 	return nil
 }

beszel/internal/entities/container/container.go

@@ -27,38 +27,41 @@ type ApiInfo struct {
 
 // Docker container resources from /containers/{id}/stats
 type ApiStats struct {
-	// Common stats
-	// Read    time.Time `json:"read"`
-	// PreRead time.Time `json:"preread"`
+	Read        time.Time `json:"read"`               // Time of stats generation
+	NumProcs    uint32    `json:"num_procs,omitzero"` // Windows specific, not populated on Linux.
+	Networks    map[string]NetworkStats
+	CPUStats    CPUStats    `json:"cpu_stats"`
+	MemoryStats MemoryStats `json:"memory_stats"`
+}
 
-	// Linux specific stats, not populated on Windows.
-	// PidsStats  PidsStats  `json:"pids_stats,omitempty"`
-	// BlkioStats BlkioStats `json:"blkio_stats,omitempty"`
+func (s *ApiStats) CalculateCpuPercentLinux(prevCpuUsage [2]uint64) float64 {
+	cpuDelta := s.CPUStats.CPUUsage.TotalUsage - prevCpuUsage[0]
+	systemDelta := s.CPUStats.SystemUsage - prevCpuUsage[1]
+	return float64(cpuDelta) / float64(systemDelta) * 100
+}
 
-	// Windows specific stats, not populated on Linux.
-	// NumProcs uint32 `json:"num_procs"`
-	// StorageStats StorageStats `json:"storage_stats,omitempty"`
-	// Networks request version >=1.21
-	Networks map[string]NetworkStats
+// from: https://github.com/docker/cli/blob/master/cli/command/container/stats_helpers.go#L185
+func (s *ApiStats) CalculateCpuPercentWindows(prevCpuUsage uint64, prevRead time.Time) float64 {
+	// Max number of 100ns intervals between the previous time read and now
+	possIntervals := uint64(s.Read.Sub(prevRead).Nanoseconds())
+	possIntervals /= 100                // Convert to number of 100ns intervals
+	possIntervals *= uint64(s.NumProcs) // Multiple by the number of processors
 
-	// Shared stats
-	CPUStats CPUStats `json:"cpu_stats,omitempty"`
-	// PreCPUStats CPUStats    `json:"precpu_stats,omitempty"` // "Pre"="Previous"
-	MemoryStats MemoryStats `json:"memory_stats,omitempty"`
+	// Intervals used
+	intervalsUsed := s.CPUStats.CPUUsage.TotalUsage - prevCpuUsage
+
+	// Percentage avoiding divide-by-zero
+	if possIntervals > 0 {
+		return float64(intervalsUsed) / float64(possIntervals) * 100.0
+	}
+	return 0.00
 }
 
 type CPUStats struct {
 	// CPU Usage. Linux and Windows.
 	CPUUsage CPUUsage `json:"cpu_usage"`
-
 	// System Usage. Linux only.
 	SystemUsage uint64 `json:"system_cpu_usage,omitempty"`
-
-	// Online CPUs. Linux only.
-	// OnlineCPUs uint32 `json:"online_cpus,omitempty"`
-
-	// Throttling Data. Linux only.
-	// ThrottlingData ThrottlingData `json:"throttling_data,omitempty"`
 }
 
 type CPUUsage struct {
@@ -66,42 +69,15 @@ type CPUUsage struct {
 	// Units: nanoseconds (Linux)
 	// Units: 100's of nanoseconds (Windows)
 	TotalUsage uint64 `json:"total_usage"`
-
-	// Total CPU time consumed per core (Linux). Not used on Windows.
-	// Units: nanoseconds.
-	// PercpuUsage []uint64 `json:"percpu_usage,omitempty"`
-
-	// Time spent by tasks of the cgroup in kernel mode (Linux).
-	// Time spent by all container processes in kernel mode (Windows).
-	// Units: nanoseconds (Linux).
-	// Units: 100's of nanoseconds (Windows). Not populated for Hyper-V Containers.
-	// UsageInKernelmode uint64 `json:"usage_in_kernelmode"`
-
-	// Time spent by tasks of the cgroup in user mode (Linux).
-	// Time spent by all container processes in user mode (Windows).
-	// Units: nanoseconds (Linux).
-	// Units: 100's of nanoseconds (Windows). Not populated for Hyper-V Containers
-	// UsageInUsermode uint64 `json:"usage_in_usermode"`
 }
 
 type MemoryStats struct {
 	// current res_counter usage for memory
 	Usage uint64 `json:"usage,omitempty"`
 	// all the stats exported via memory.stat.
-	Stats MemoryStatsStats `json:"stats,omitempty"`
-	// maximum usage ever recorded.
-	// MaxUsage uint64 `json:"max_usage,omitempty"`
-	// TODO(vishh): Export these as stronger types.
-	// number of times memory usage hits limits.
-	// Failcnt uint64 `json:"failcnt,omitempty"`
-	// Limit   uint64 `json:"limit,omitempty"`
-
-	// // committed bytes
-	// Commit uint64 `json:"commitbytes,omitempty"`
-	// // peak committed bytes
-	// CommitPeak uint64 `json:"commitpeakbytes,omitempty"`
-	// // private working set
-	// PrivateWorkingSet uint64 `json:"privateworkingset,omitempty"`
+	Stats MemoryStatsStats `json:"stats"`
+	// private working set (Windows only)
+	PrivateWorkingSet uint64 `json:"privateworkingset,omitempty"`
 }
 
 type MemoryStatsStats struct {
@@ -119,7 +95,6 @@ type NetworkStats struct {
 type prevNetStats struct {
 	Sent uint64
 	Recv uint64
-	Time time.Time
 }
 
 // Docker container stats
@@ -131,4 +106,5 @@ type Stats struct {
 	NetworkRecv float64      `json:"nr"`
 	PrevCpu     [2]uint64    `json:"-"`
 	PrevNet     prevNetStats `json:"-"`
+	PrevRead    time.Time    `json:"-"`
 }