Add dmcache input plugin

plugins/inputs/all/all.go

@@ -14,6 +14,7 @@ import (
 	_ "github.com/influxdata/telegraf/plugins/inputs/couchbase"
 	_ "github.com/influxdata/telegraf/plugins/inputs/couchdb"
 	_ "github.com/influxdata/telegraf/plugins/inputs/disque"
+	_ "github.com/influxdata/telegraf/plugins/inputs/dmcache"
 	_ "github.com/influxdata/telegraf/plugins/inputs/dns_query"
 	_ "github.com/influxdata/telegraf/plugins/inputs/docker"
 	_ "github.com/influxdata/telegraf/plugins/inputs/dovecot"

plugins/inputs/dmcache/README.md

@@ -0,0 +1,15 @@
+# DMCache Input Plugin
+
+This plugin provide a native collection for dmsetup based statistics for dm-cache.
+
+This plugin requires sudo, that is why you should setup and be sure that the telegraf is able to execute sudo without a password.
+
+`sudo /sbin/dmsetup status --target cache` is the full command that telegraf will run for debugging purposes.
+
+## Configuration
+
+```
+[[inputs.dmcache]]
+  ## Whether to report per-device stats or not
+  per_device = true
+```

plugins/inputs/dmcache/dmcache.go

@@ -0,0 +1,51 @@
+package dmcache
+
+import (
+	"os/exec"
+	"strings"
+
+	"github.com/influxdata/telegraf"
+	"github.com/influxdata/telegraf/plugins/inputs"
+)
+
+type DMCache struct {
+	PerDevice        bool `toml:"per_device"`
+	getCurrentStatus func() ([]string, error)
+}
+
+var sampleConfig = `
+  ## Whether to report per-device stats or not
+  per_device = true
+`
+
+func (c *DMCache) SampleConfig() string {
+	return sampleConfig
+}
+
+func (c *DMCache) Description() string {
+	return "Provide a native collection for dmsetup based statistics for dm-cache"
+}
+
+func dmSetupStatus() ([]string, error) {
+	out, err := exec.Command("/bin/sh", "-c", "sudo /sbin/dmsetup status --target cache").Output()
+	if err != nil {
+		return nil, err
+	}
+	if string(out) == "No devices found\n" {
+		return []string{}, nil
+	}
+
+	outString := strings.TrimRight(string(out), "\n")
+	status := strings.Split(outString, "\n")
+
+	return status, nil
+}
+
+func init() {
+	inputs.Add("dmcache", func() telegraf.Input {
+		return &DMCache{
+			PerDevice:        true,
+			getCurrentStatus: dmSetupStatus,
+		}
+	})
+}

plugins/inputs/dmcache/dmcache_linux.go

@@ -0,0 +1,131 @@
+// +build linux
+
+package dmcache
+
+import (
+	"strconv"
+	"strings"
+
+	"errors"
+
+	"github.com/influxdata/telegraf"
+)
+
+const metricName = "dmcache"
+
+func (c *DMCache) Gather(acc telegraf.Accumulator) error {
+	outputLines, err := c.getCurrentStatus()
+	if err != nil {
+		return err
+	}
+
+	total := make(map[string]interface{})
+
+	for _, s := range outputLines {
+		fields, err := parseDMSetupStatus(s)
+		if err != nil {
+			return err
+		}
+
+		if c.PerDevice {
+			tags := map[string]string{"device": fields["device"].(string)}
+			acc.AddFields(metricName, fields, tags)
+		}
+		aggregateStats(total, fields)
+	}
+
+	acc.AddFields(metricName, total, map[string]string{"device": "all"})
+
+	return nil
+}
+
+func parseDMSetupStatus(line string) (map[string]interface{}, error) {
+	var err error
+	parseError := errors.New("Output from dmsetup could not be parsed")
+	status := make(map[string]interface{})
+	values := strings.Fields(line)
+	if len(values) < 15 {
+		return nil, parseError
+	}
+
+	status["device"] = strings.TrimRight(values[0], ":")
+	status["length"], err = strconv.Atoi(values[2])
+	if err != nil {
+		return nil, err
+	}
+	status["target"] = values[3]
+	status["metadata_blocksize"], err = strconv.Atoi(values[4])
+	if err != nil {
+		return nil, err
+	}
+	metadata := strings.Split(values[5], "/")
+	if len(metadata) != 2 {
+		return nil, parseError
+	}
+	status["metadata_used"], err = strconv.Atoi(metadata[0])
+	if err != nil {
+		return nil, err
+	}
+	status["metadata_total"], err = strconv.Atoi(metadata[1])
+	if err != nil {
+		return nil, err
+	}
+	status["cache_blocksize"], err = strconv.Atoi(values[6])
+	if err != nil {
+		return nil, err
+	}
+	cache := strings.Split(values[7], "/")
+	if len(cache) != 2 {
+		return nil, parseError
+	}
+	status["cache_used"], err = strconv.Atoi(cache[0])
+	if err != nil {
+		return nil, err
+	}
+	status["cache_total"], err = strconv.Atoi(cache[1])
+	if err != nil {
+		return nil, err
+	}
+	status["read_hits"], err = strconv.Atoi(values[8])
+	if err != nil {
+		return nil, err
+	}
+	status["read_misses"], err = strconv.Atoi(values[9])
+	if err != nil {
+		return nil, err
+	}
+	status["write_hits"], err = strconv.Atoi(values[10])
+	if err != nil {
+		return nil, err
+	}
+	status["write_misses"], err = strconv.Atoi(values[11])
+	if err != nil {
+		return nil, err
+	}
+	status["demotions"], err = strconv.Atoi(values[12])
+	if err != nil {
+		return nil, err
+	}
+	status["promotions"], err = strconv.Atoi(values[13])
+	if err != nil {
+		return nil, err
+	}
+	status["dirty"], err = strconv.Atoi(values[14])
+	if err != nil {
+		return nil, err
+	}
+
+	return status, nil
+}
+
+func aggregateStats(total, fields map[string]interface{}) {
+	for key, value := range fields {
+		if _, ok := value.(int); ok {
+			if _, ok := total[key]; ok {
+				total[key] = total[key].(int) + value.(int)
+			} else {
+				total[key] = value.(int)
+			}
+		}
+	}
+}

plugins/inputs/dmcache/dmcache_notlinux.go

@@ -0,0 +1,11 @@
+// +build !linux
+
+package dmcache
+
+import (
+	"github.com/influxdata/telegraf"
+)
+
+func (c *DMCache) Gather(acc telegraf.Accumulator) error {
+	return nil
+}