dashboard: CPU, memory, diskIO and traffic on the footer (#15950)

* dashboard: footer, deep state update

* dashboard: resolve asset path

* dashboard: prevent state update on every reconnection

* dashboard: fix linter issue

* dashboard, cmd: minor UI fix, include commit hash

* dashboard: gitCommit renamed to commit

* dashboard: move the geth version to the right, make commit optional

* dashboard: memory, traffic and CPU on footer

* dashboard: fix merge

* dashboard: CPU, diskIO on footer

* dashboard: rename variables, use group declaration

* dashboard: docs

vendor/github.com/elastic/gosigar/sigar_interface.go

@@ -0,0 +1,197 @@
+package gosigar
+
+import (
+	"time"
+)
+
+type ErrNotImplemented struct {
+	OS string
+}
+
+func (e ErrNotImplemented) Error() string {
+	return "not implemented on " + e.OS
+}
+
+func IsNotImplemented(err error) bool {
+	switch err.(type) {
+	case ErrNotImplemented, *ErrNotImplemented:
+		return true
+	default:
+		return false
+	}
+}
+
+type Sigar interface {
+	CollectCpuStats(collectionInterval time.Duration) (<-chan Cpu, chan<- struct{})
+	GetLoadAverage() (LoadAverage, error)
+	GetMem() (Mem, error)
+	GetSwap() (Swap, error)
+	GetFileSystemUsage(string) (FileSystemUsage, error)
+	GetFDUsage() (FDUsage, error)
+	GetRusage(who int) (Rusage, error)
+}
+
+type Cpu struct {
+	User    uint64
+	Nice    uint64
+	Sys     uint64
+	Idle    uint64
+	Wait    uint64
+	Irq     uint64
+	SoftIrq uint64
+	Stolen  uint64
+}
+
+func (cpu *Cpu) Total() uint64 {
+	return cpu.User + cpu.Nice + cpu.Sys + cpu.Idle +
+		cpu.Wait + cpu.Irq + cpu.SoftIrq + cpu.Stolen
+}
+
+func (cpu Cpu) Delta(other Cpu) Cpu {
+	return Cpu{
+		User:    cpu.User - other.User,
+		Nice:    cpu.Nice - other.Nice,
+		Sys:     cpu.Sys - other.Sys,
+		Idle:    cpu.Idle - other.Idle,
+		Wait:    cpu.Wait - other.Wait,
+		Irq:     cpu.Irq - other.Irq,
+		SoftIrq: cpu.SoftIrq - other.SoftIrq,
+		Stolen:  cpu.Stolen - other.Stolen,
+	}
+}
+
+type LoadAverage struct {
+	One, Five, Fifteen float64
+}
+
+type Uptime struct {
+	Length float64
+}
+
+type Mem struct {
+	Total      uint64
+	Used       uint64
+	Free       uint64
+	ActualFree uint64
+	ActualUsed uint64
+}
+
+type Swap struct {
+	Total uint64
+	Used  uint64
+	Free  uint64
+}
+
+type CpuList struct {
+	List []Cpu
+}
+
+type FDUsage struct {
+	Open   uint64
+	Unused uint64
+	Max    uint64
+}
+
+type FileSystem struct {
+	DirName     string
+	DevName     string
+	TypeName    string
+	SysTypeName string
+	Options     string
+	Flags       uint32
+}
+
+type FileSystemList struct {
+	List []FileSystem
+}
+
+type FileSystemUsage struct {
+	Total     uint64
+	Used      uint64
+	Free      uint64
+	Avail     uint64
+	Files     uint64
+	FreeFiles uint64
+}
+
+type ProcList struct {
+	List []int
+}
+
+type RunState byte
+
+const (
+	RunStateSleep   = 'S'
+	RunStateRun     = 'R'
+	RunStateStop    = 'T'
+	RunStateZombie  = 'Z'
+	RunStateIdle    = 'D'
+	RunStateUnknown = '?'
+)
+
+type ProcState struct {
+	Name      string
+	Username  string
+	State     RunState
+	Ppid      int
+	Pgid      int
+	Tty       int
+	Priority  int
+	Nice      int
+	Processor int
+}
+
+type ProcMem struct {
+	Size        uint64
+	Resident    uint64
+	Share       uint64
+	MinorFaults uint64
+	MajorFaults uint64
+	PageFaults  uint64
+}
+
+type ProcTime struct {
+	StartTime uint64
+	User      uint64
+	Sys       uint64
+	Total     uint64
+}
+
+type ProcArgs struct {
+	List []string
+}
+
+type ProcEnv struct {
+	Vars map[string]string
+}
+
+type ProcExe struct {
+	Name string
+	Cwd  string
+	Root string
+}
+
+type ProcFDUsage struct {
+	Open      uint64
+	SoftLimit uint64
+	HardLimit uint64
+}
+
+type Rusage struct {
+	Utime    time.Duration
+	Stime    time.Duration
+	Maxrss   int64
+	Ixrss    int64
+	Idrss    int64
+	Isrss    int64
+	Minflt   int64
+	Majflt   int64
+	Nswap    int64
+	Inblock  int64
+	Oublock  int64
+	Msgsnd   int64
+	Msgrcv   int64
+	Nsignals int64
+	Nvcsw    int64
+	Nivcsw   int64
+}