feat(inputs.linux_cpu): Add CPUFreq input plugin for Linux (v3)

plugins/inputs/all/linux_cpu.go

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+//go:build !custom || inputs || inputs.linux_cpu
+
+package all
+
+import _ "github.com/influxdata/telegraf/plugins/inputs/linux_cpu" // register plugin

plugins/inputs/linux_cpu/README.md

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+# Linux CPU Input Plugin
+
+The `linux_cpu` plugin gathers CPU metrics exposed on Linux-based systems.
+
+## Configuration
+
+```toml @sample.conf
+# Collects CPU metrics exposed on Linux
+[[inputs.linux_cpu]]
+  ## Path for sysfs filesystem.
+  ## See https://www.kernel.org/doc/Documentation/filesystems/sysfs.txt
+  ## Defaults:
+  # host_sys = "/sys"
+
+  ## CPU metrics collected by the plugin.
+  ## Supported options:
+  ## "cpufreq", "thermal"
+  ## Defaults:
+  # metrics = ["cpufreq"]
+```
+
+## Metrics
+
+The following tags are emitted by the plugin under the name `linux_cpu`:
+
+| Tag   | Description           |
+|-------|-----------------------|
+| `cpu` | Identifier of the CPU |
+
+The following fields are emitted by the plugin when selecting `cpufreq`:
+
+| Metric name (field) | Description                                                | Units |
+|---------------------|------------------------------------------------------------|-------|
+| `scaling_cur_freq`  | Current frequency of the CPU as determined by CPUFreq      | KHz   |
+| `scaling_min_freq`  | Minimum frequency the governor can scale to                | KHz   |
+| `scaling_max_freq`  | Maximum frequency the governor can scale to                | KHz   |
+| `cpuinfo_cur_freq`  | Current frequency of the CPU as determined by the hardware | KHz   |
+| `cpuinfo_min_freq`  | Minimum operating frequency of the CPU                     | KHz   |
+| `cpuinfo_max_freq`  | Maximum operating frequency of the CPU                     | KHz   |
+
+The following fields are emitted by the plugin when selecting `thermal`:
+
+| Metric name (field)   | Description                                                 | Units |
+|-----------------------|-------------------------------------------------------------|-------|
+| `throttle_count`      | Number of thermal throttle events reported by the CPU       |       |
+| `throttle_max_time`   | Maximum amount of time CPU was in throttled state           | ms    |
+| `throtlle_total_time` | Cumulative time during which the CPU was in throttled state | ms    |
+
+## Example Output
+
+```shell
+> linux_cpu,cpu=0,host=go scaling_max_freq=4700000i,cpuinfo_min_freq=400000i,cpuinfo_max_freq=4700000i,throttle_count=0i,throttle_max_time=0i,throttle_total_time=0i,scaling_cur_freq=803157i,scaling_min_freq=400000i 1617621150000000000
+> linux_cpu,cpu=1,host=go throttle_total_time=0i,scaling_cur_freq=802939i,scaling_min_freq=400000i,scaling_max_freq=4700000i,cpuinfo_min_freq=400000i,cpuinfo_max_freq=4700000i,throttle_count=0i,throttle_max_time=0i 1617621150000000000
+> linux_cpu,cpu=10,host=go throttle_max_time=0i,throttle_total_time=0i,scaling_cur_freq=838343i,scaling_min_freq=400000i,scaling_max_freq=4700000i,cpuinfo_min_freq=400000i,cpuinfo_max_freq=4700000i,throttle_count=0i 1617621150000000000
+> linux_cpu,cpu=11,host=go cpuinfo_max_freq=4700000i,throttle_count=0i,throttle_max_time=0i,throttle_total_time=0i,scaling_cur_freq=800054i,scaling_min_freq=400000i,scaling_max_freq=4700000i,cpuinfo_min_freq=400000i 1617621150000000000
+> linux_cpu,cpu=2,host=go throttle_total_time=0i,scaling_cur_freq=800404i,scaling_min_freq=400000i,scaling_max_freq=4700000i,cpuinfo_min_freq=400000i,cpuinfo_max_freq=4700000i,throttle_count=0i,throttle_max_time=0i 1617621150000000000
+> linux_cpu,cpu=3,host=go throttle_total_time=0i,scaling_cur_freq=800126i,scaling_min_freq=400000i,scaling_max_freq=4700000i,cpuinfo_min_freq=400000i,cpuinfo_max_freq=4700000i,throttle_count=0i,throttle_max_time=0i 1617621150000000000
+> linux_cpu,cpu=4,host=go cpuinfo_max_freq=4700000i,throttle_count=0i,throttle_max_time=0i,throttle_total_time=0i,scaling_cur_freq=800359i,scaling_min_freq=400000i,scaling_max_freq=4700000i,cpuinfo_min_freq=400000i 1617621150000000000
+> linux_cpu,cpu=5,host=go throttle_max_time=0i,throttle_total_time=0i,scaling_cur_freq=800093i,scaling_min_freq=400000i,scaling_max_freq=4700000i,cpuinfo_min_freq=400000i,cpuinfo_max_freq=4700000i,throttle_count=0i 1617621150000000000
+> linux_cpu,cpu=6,host=go cpuinfo_max_freq=4700000i,throttle_count=0i,throttle_max_time=0i,throttle_total_time=0i,scaling_cur_freq=741646i,scaling_min_freq=400000i,scaling_max_freq=4700000i,cpuinfo_min_freq=400000i 1617621150000000000
+> linux_cpu,cpu=7,host=go scaling_cur_freq=700006i,scaling_min_freq=400000i,scaling_max_freq=4700000i,cpuinfo_min_freq=400000i,cpuinfo_max_freq=4700000i,throttle_count=0i,throttle_max_time=0i,throttle_total_time=0i 1617621150000000000
+> linux_cpu,cpu=8,host=go throttle_max_time=0i,throttle_total_time=0i,scaling_cur_freq=700046i,scaling_min_freq=400000i,scaling_max_freq=4700000i,cpuinfo_min_freq=400000i,cpuinfo_max_freq=4700000i,throttle_count=0i 1617621150000000000
+> linux_cpu,cpu=9,host=go throttle_count=0i,throttle_max_time=0i,throttle_total_time=0i,scaling_cur_freq=700075i,scaling_min_freq=400000i,scaling_max_freq=4700000i,cpuinfo_min_freq=400000i,cpuinfo_max_freq=4700000i 1617621150000000000
+```

plugins/inputs/linux_cpu/linux_cpu.go

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+//go:build linux
+
+package linux_cpu
+
+import (
+	_ "embed"
+
+	"fmt"
+	"io"
+	"os"
+	"path"
+	"path/filepath"
+	"strconv"
+	"strings"
+
+	"github.com/influxdata/telegraf"
+	"github.com/influxdata/telegraf/internal/choice"
+	"github.com/influxdata/telegraf/plugins/inputs"
+)
+
+const (
+	defaultHostSys = "/sys"
+	cpufreq        = "cpufreq"
+	thermal        = "thermal"
+)
+
+type LinuxCPU struct {
+	Log       telegraf.Logger `toml:"-"`
+	PathSysfs string          `toml:"host_sys"`
+	Metrics   []string        `toml:"metrics"`
+	cpus      []cpu
+}
+
+type cpu struct {
+	id    string
+	path  string
+	props map[string]string
+}
+
+type prop struct {
+	name     string
+	path     string
+	optional bool
+}
+
+//go:embed sample.conf
+var sampleConfig string
+
+func (g *LinuxCPU) SampleConfig() string {
+	return sampleConfig
+}
+
+func (g *LinuxCPU) Init() error {
+	if g.PathSysfs == "" {
+		g.PathSysfs = defaultHostSys
+	}
+
+	if len(g.Metrics) == 0 {
+		// The user has not enabled any of the metrics
+		return fmt.Errorf("no metrics selected")
+	}
+
+	cpus, err := g.discoverCpus()
+	if err != nil {
+		return err
+	} else if len(cpus) == 0 {
+		// Although the user has specified metrics to collect, `discoverCpus` failed to find the required metrics
+		return fmt.Errorf("no CPUs detected to track")
+	}
+	g.cpus = cpus
+
+	return nil
+}
+
+func (g *LinuxCPU) Gather(acc telegraf.Accumulator) error {
+	for _, cpu := range g.cpus {
+		fields := make(map[string]interface{})
+		tags := map[string]string{"cpu": cpu.id}
+
+		failed := false
+		for name, propPath := range cpu.props {
+			v, err := readUintFromFile(propPath)
+			if err != nil {
+				acc.AddError(err)
+				failed = true
+				break
+			}
+
+			fields[name] = v
+		}
+
+		if !failed {
+			acc.AddFields("linux_cpu", fields, tags)
+		}
+	}
+
+	return nil
+}
+
+func (g *LinuxCPU) discoverCpus() ([]cpu, error) {
+	var cpus []cpu
+
+	glob := path.Join(g.PathSysfs, "devices/system/cpu/cpu[0-9]*")
+	cpuDirs, err := filepath.Glob(glob)
+	if err != nil {
+		return nil, err
+	}
+
+	if len(cpuDirs) == 0 {
+		return nil, fmt.Errorf("no CPUs detected at: %s", glob)
+	}
+
+	for _, dir := range cpuDirs {
+		_, cpuName := filepath.Split(dir)
+		cpuNum := strings.TrimPrefix(cpuName, "cpu")
+
+		cpu := cpu{
+			id:    cpuNum,
+			path:  dir,
+			props: make(map[string]string),
+		}
+
+		var props []prop
+
+		if choice.Contains(cpufreq, g.Metrics) {
+			props = append(props,
+				prop{name: "scaling_cur_freq", path: "cpufreq/scaling_cur_freq", optional: false},
+				prop{name: "scaling_min_freq", path: "cpufreq/scaling_min_freq", optional: false},
+				prop{name: "scaling_max_freq", path: "cpufreq/scaling_max_freq", optional: false},
+				prop{name: "cpuinfo_cur_freq", path: "cpufreq/cpuinfo_cur_freq", optional: true},
+				prop{name: "cpuinfo_min_freq", path: "cpufreq/cpuinfo_min_freq", optional: true},
+				prop{name: "cpuinfo_max_freq", path: "cpufreq/cpuinfo_max_freq", optional: true},
+			)
+		}
+
+		if choice.Contains(thermal, g.Metrics) {
+			props = append(
+				props,
+				prop{name: "throttle_count", path: "thermal_throttle/core_throttle_count", optional: false},
+				prop{name: "throttle_max_time", path: "thermal_throttle/core_throttle_max_time_ms", optional: false},
+				prop{name: "throttle_total_time", path: "thermal_throttle/core_throttle_total_time_ms", optional: false},
+			)
+		}
+
+		var failed = false
+		for _, prop := range props {
+			propPath := filepath.Join(dir, prop.path)
+			err := validatePath(propPath)
+			if err != nil {
+				if prop.optional {
+					continue
+				}
+
+				g.Log.Warnf("Failed to load property %s: %v", propPath, err)
+				failed = true
+				break
+			}
+
+			cpu.props[prop.name] = propPath
+		}
+
+		if len(cpu.props) == 0 {
+			g.Log.Warnf("No properties enabled/loaded for CPU %s", cpuNum)
+			failed = true
+		}
+
+		if !failed {
+			cpus = append(cpus, cpu)
+		}
+	}
+	return cpus, nil
+}
+
+func init() {
+	inputs.Add("linux_cpu", func() telegraf.Input {
+		return &LinuxCPU{
+			Metrics: []string{"cpufreq"},
+		}
+	})
+}
+
+func validatePath(propPath string) error {
+	f, err := os.Open(propPath)
+
+	if os.IsNotExist(err) {
+		return fmt.Errorf("CPU property does not exist: [%s]", propPath)
+	}
+
+	if err != nil {
+		return fmt.Errorf("cannot get system information for CPU property: [%s] - %v", propPath, err)
+	}
+
+	_ = f.Close() // File is not written to, closing should be safe
+	return nil
+}
+
+func readUintFromFile(propPath string) (uint64, error) {
+	f, err := os.Open(propPath)
+	if err != nil {
+		return 0, err
+	}
+	defer f.Close()
+
+	buffer := make([]byte, 22)
+
+	n, err := f.Read(buffer)
+	if err != nil && err != io.EOF {
+		return 0, fmt.Errorf("error on reading file, err: %v", err)
+	} else if n == 0 {
+		return 0, fmt.Errorf("error on reading file, file is empty")
+	}
+
+	return strconv.ParseUint(string(buffer[:n-1]), 10, 64)
+}

plugins/inputs/linux_cpu/linux_cpu_nonlinux.go

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+//go:build !linux
+
+package linux_cpu