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kernel.go
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kernel.go
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//go:generate ../../../tools/readme_config_includer/generator
//go:build linux
package kernel
import (
"bytes"
_ "embed"
"fmt"
"os"
"path/filepath"
"strconv"
"github.com/influxdata/telegraf"
"github.com/influxdata/telegraf/plugins/inputs"
)
//go:embed sample.conf
var sampleConfig string
// /proc/stat file line prefixes to gather stats on:
var (
interrupts = []byte("intr")
contextSwitches = []byte("ctxt")
processesForked = []byte("processes")
diskPages = []byte("page")
bootTime = []byte("btime")
)
type Kernel struct {
ConfigCollect []string `toml:"collect"`
optCollect map[string]bool
statFile string
entropyStatFile string
ksmStatsDir string
}
func (k *Kernel) Init() error {
k.optCollect = make(map[string]bool, len(k.ConfigCollect))
for _, v := range k.ConfigCollect {
k.optCollect[v] = true
}
if k.optCollect["ksm"] {
if _, err := os.Stat(k.ksmStatsDir); os.IsNotExist(err) {
// ksm probably not enabled in the kernel, bail out early
return fmt.Errorf("directory %q does not exist. Is KSM enabled in this kernel?", k.ksmStatsDir)
}
}
return nil
}
func (*Kernel) SampleConfig() string {
return sampleConfig
}
func (k *Kernel) Gather(acc telegraf.Accumulator) error {
data, err := k.getProcValueBytes(k.statFile)
if err != nil {
return err
}
entropyValue, err := k.getProcValueInt(k.entropyStatFile)
if err != nil {
return err
}
fields := make(map[string]interface{})
fields["entropy_avail"] = entropyValue
dataFields := bytes.Fields(data)
for i, field := range dataFields {
switch {
case bytes.Equal(field, interrupts):
m, err := strconv.ParseInt(string(dataFields[i+1]), 10, 64)
if err != nil {
return err
}
fields["interrupts"] = m
case bytes.Equal(field, contextSwitches):
m, err := strconv.ParseInt(string(dataFields[i+1]), 10, 64)
if err != nil {
return err
}
fields["context_switches"] = m
case bytes.Equal(field, processesForked):
m, err := strconv.ParseInt(string(dataFields[i+1]), 10, 64)
if err != nil {
return err
}
fields["processes_forked"] = m
case bytes.Equal(field, bootTime):
m, err := strconv.ParseInt(string(dataFields[i+1]), 10, 64)
if err != nil {
return err
}
fields["boot_time"] = m
case bytes.Equal(field, diskPages):
in, err := strconv.ParseInt(string(dataFields[i+1]), 10, 64)
if err != nil {
return err
}
out, err := strconv.ParseInt(string(dataFields[i+2]), 10, 64)
if err != nil {
return err
}
fields["disk_pages_in"] = in
fields["disk_pages_out"] = out
}
}
if k.optCollect["ksm"] {
stats := []string{
"full_scans", "max_page_sharing",
"merge_across_nodes", "pages_shared",
"pages_sharing", "pages_to_scan",
"pages_unshared", "pages_volatile",
"run", "sleep_millisecs",
"stable_node_chains", "stable_node_chains_prune_millisecs",
"stable_node_dups", "use_zero_pages",
}
// these exist in very recent Linux versions only, but useful to include if there.
extraStats := []string{"general_profit"}
for _, f := range stats {
m, err := k.getProcValueInt(filepath.Join(k.ksmStatsDir, f))
if err != nil {
return err
}
fields["ksm_"+f] = m
}
for _, f := range extraStats {
m, err := k.getProcValueInt(filepath.Join(k.ksmStatsDir, f))
if err != nil {
// if an extraStats metric doesn't exist in our kernel version, ignore it.
continue
}
fields["ksm_"+f] = m
}
}
acc.AddCounter("kernel", fields, map[string]string{})
return nil
}
func (k *Kernel) getProcValueBytes(path string) ([]byte, error) {
if _, err := os.Stat(path); os.IsNotExist(err) {
return nil, fmt.Errorf("Path %q does not exist", path)
} else if err != nil {
return nil, err
}
data, err := os.ReadFile(path)
if err != nil {
return nil, fmt.Errorf("failed to read from %q: %w", path, err)
}
return data, nil
}
func (k *Kernel) getProcValueInt(path string) (int64, error) {
data, err := k.getProcValueBytes(path)
if err != nil {
return -1, err
}
m, err := strconv.ParseInt(string(bytes.TrimSpace(data)), 10, 64)
if err != nil {
return -1, fmt.Errorf("failed to parse %q as an integer: %w", data, err)
}
return m, nil
}
func init() {
inputs.Add("kernel", func() telegraf.Input {
return &Kernel{
statFile: "/proc/stat",
entropyStatFile: "/proc/sys/kernel/random/entropy_avail",
ksmStatsDir: "/sys/kernel/mm/ksm",
}
})
}