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

@@ -14,13 +14,9 @@ import (
 	"sync"
 	"time"
 
-	"regexp"
-
 	"github.com/blang/semver"
 )
 
-var headerRegexp = regexp.MustCompile(`\ADocker/.+\s\((.+)\)\z`)
-
 type dockerManager struct {
 	client              *http.Client                // Client to query Docker API
 	wg                  sync.WaitGroup              // WaitGroup to wait for all goroutines to finish
@@ -30,6 +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
@@ -73,6 +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
@@ -84,8 +83,7 @@ func (dm *dockerManager) getDockerStats() ([]*container.Stats, error) {
 
 	var failedContainers []*container.ApiInfo
 
-	for i := range dm.apiContainerList {
+	for _, ctr := range dm.apiContainerList {
-		ctr := dm.apiContainerList[i]
 		ctr.IdShort = ctr.Id[:12]
 		dm.validIds[ctr.IdShort] = struct{}{}
 		// check if container is less than 1 minute old (possible restart)
@@ -171,15 +169,13 @@ func (dm *dockerManager) updateContainerStats(ctr *container.ApiInfo) error {
 		return err
 	}
 
+	// calculate cpu and memory stats
 	var usedMemory uint64
 	var cpuPct float64
 
-	if getDockerOS(resp.Header.Get("Server")) == "windows" {
+	if dm.isWindows {
-
 		usedMemory = res.MemoryStats.PrivateWorkingSet
-		cpuPct = calculateCPUPercentWindows(res, stats.PrevCpu[0], stats.PrevRead)
+		cpuPct = res.CalculateCpuPercentWindows(stats.PrevCpu[0], stats.PrevRead)
-		stats.PrevRead = res.Read
-
 	} else {
 		// check if container has valid data, otherwise may be in restart loop (#103)
 		if res.MemoryStats.Usage == 0 {
@@ -191,9 +187,7 @@ func (dm *dockerManager) updateContainerStats(ctr *container.ApiInfo) error {
 		}
 		usedMemory = res.MemoryStats.Usage - memCache
 
-		cpuDelta := res.CPUStats.CPUUsage.TotalUsage - stats.PrevCpu[0]
+		cpuPct = res.CalculateCpuPercentLinux(stats.PrevCpu)
-		systemDelta := res.CPUStats.SystemUsage - stats.PrevCpu[1]
-		cpuPct = float64(cpuDelta) / float64(systemDelta) * 100
 	}
 
 	if cpuPct > 100 {
@@ -210,18 +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
 }
@@ -337,31 +331,3 @@ func getDockerHost() string {
 	}
 	return scheme + socks[0]
 }
-
-// getDockerOS returns the operating system based on the server header from the daemon.
-// from: https://github.com/docker/cli/blob/master/vendor/github.com/docker/docker/client/utils.go#L34
-func getDockerOS(serverHeader string) string {
-	var osType string
-	matches := headerRegexp.FindStringSubmatch(serverHeader)
-	if len(matches) > 0 {
-		osType = matches[1]
-	}
-	return osType
-}
-
-// from: https://github.com/docker/cli/blob/master/cli/command/container/stats_helpers.go#L185
-func calculateCPUPercentWindows(v container.ApiStats, prevCPUSsage uint64, prevRead time.Time) float64 {
-	// Max number of 100ns intervals between the previous time read and now
-	possIntervals := uint64(v.Read.Sub(prevRead).Nanoseconds())
-	possIntervals /= 100                // Convert to number of 100ns intervals
-	possIntervals *= uint64(v.NumProcs) // Multiple by the number of processors
-
-	// Intervals used
-	intervalsUsed := v.CPUStats.CPUUsage.TotalUsage - prevCPUSsage
-
-	// Percentage avoiding divide-by-zero
-	if possIntervals > 0 {
-		return float64(intervalsUsed) / float64(possIntervals) * 100.0
-	}
-	return 0.00
-}

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"`               // Time of stats generation
-	Read time.Time `json:"read"`
+	NumProcs    uint32    `json:"num_procs,omitzero"` // Windows specific, not populated on Linux.
-	// PreRead time.Time `json:"preread"`
+	Networks    map[string]NetworkStats
+	CPUStats    CPUStats    `json:"cpu_stats"`
+	MemoryStats MemoryStats `json:"memory_stats"`
+}
 
-	// Linux specific stats, not populated on Windows.
+func (s *ApiStats) CalculateCpuPercentLinux(prevCpuUsage [2]uint64) float64 {
-	// PidsStats  PidsStats  `json:"pids_stats,omitempty"`
+	cpuDelta := s.CPUStats.CPUUsage.TotalUsage - prevCpuUsage[0]
-	// BlkioStats BlkioStats `json:"blkio_stats,omitempty"`
+	systemDelta := s.CPUStats.SystemUsage - prevCpuUsage[1]
+	return float64(cpuDelta) / float64(systemDelta) * 100
+}
 
-	// Windows specific stats, not populated on Linux.
+// from: https://github.com/docker/cli/blob/master/cli/command/container/stats_helpers.go#L185
-	NumProcs uint32 `json:"num_procs"`
+func (s *ApiStats) CalculateCpuPercentWindows(prevCpuUsage uint64, prevRead time.Time) float64 {
-	// StorageStats StorageStats `json:"storage_stats,omitempty"`
+	// Max number of 100ns intervals between the previous time read and now
-	// Networks request version >=1.21
+	possIntervals := uint64(s.Read.Sub(prevRead).Nanoseconds())
-	Networks map[string]NetworkStats
+	possIntervals /= 100                // Convert to number of 100ns intervals
+	possIntervals *= uint64(s.NumProcs) // Multiple by the number of processors
 
-	// Shared stats
+	// Intervals used
-	CPUStats CPUStats `json:"cpu_stats,omitempty"`
+	intervalsUsed := s.CPUStats.CPUUsage.TotalUsage - prevCpuUsage
-	// PreCPUStats CPUStats    `json:"precpu_stats,omitempty"` // "Pre"="Previous"
+
-	MemoryStats MemoryStats `json:"memory_stats,omitempty"`
+	// 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 {
@@ -66,41 +69,14 @@ 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"`
+	Stats MemoryStatsStats `json:"stats"`
-	// maximum usage ever recorded.
+	// private working set (Windows only)
-	// 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"`
 }
 
@@ -119,7 +95,6 @@ type NetworkStats struct {
 type prevNetStats struct {
 	Sent uint64
 	Recv uint64
-	Time time.Time
 }
 
 // Docker container stats