Input plugin for running ntp queries

see #235

plugins/inputs/EXAMPLE_README.md

@@ -30,8 +30,6 @@ The example plugin gathers metrics about example things
 
 ### Example Output:
 
-Give an example `-test` output here
-
 ```
 $ ./telegraf -config telegraf.conf -input-filter example -test
 measurement1,tag1=foo,tag2=bar field1=1i,field2=2.1 1453831884664956455

plugins/inputs/all/all.go

@@ -29,6 +29,7 @@ import (
 	_ "github.com/influxdata/telegraf/plugins/inputs/net_response"
 	_ "github.com/influxdata/telegraf/plugins/inputs/nginx"
 	_ "github.com/influxdata/telegraf/plugins/inputs/nsq"
+	_ "github.com/influxdata/telegraf/plugins/inputs/ntpq"
 	_ "github.com/influxdata/telegraf/plugins/inputs/passenger"
 	_ "github.com/influxdata/telegraf/plugins/inputs/phpfpm"
 	_ "github.com/influxdata/telegraf/plugins/inputs/ping"

plugins/inputs/ntpq/README.md

@@ -0,0 +1,60 @@
+# ntpq Input Plugin
+
+Get standard NTP query metrics, requires ntpq executable.
+
+Below is the documentation of the various headers returned from the NTP query
+command when running `ntpq -p`.
+
+- remote – The remote peer or server being synced to. “LOCAL” is this local host
+(included in case there are no remote peers or servers available);
+- refid – Where or what the remote peer or server is itself synchronised to;
+- st (stratum) – The remote peer or server Stratum
+- t (type) – Type (u: unicast or manycast client, b: broadcast or multicast client,
+l: local reference clock, s: symmetric peer, A: manycast server,
+B: broadcast server, M: multicast server, see “Automatic Server Discovery“);
+- when – When last polled (seconds ago, “h” hours ago, or “d” days ago);
+- poll – Polling frequency: rfc5905 suggests this ranges in NTPv4 from 4 (16s)
+to 17 (36h) (log2 seconds), however observation suggests the actual displayed
+value is seconds for a much smaller range of 64 (26) to 1024 (210) seconds;
+- reach – An 8-bit left-shift shift register value recording polls (bit set =
+successful, bit reset = fail) displayed in octal;
+- delay – Round trip communication delay to the remote peer or server (milliseconds);
+- offset – Mean offset (phase) in the times reported between this local host and
+the remote peer or server (RMS, milliseconds);
+- jitter – Mean deviation (jitter) in the time reported for that remote peer or
+server (RMS of difference of multiple time samples, milliseconds);
+
+### Configuration:
+
+```toml
+# Get standard NTP query metrics, requires ntpq executable
+[[inputs.ntpq]]
+  ## If false, set the -n ntpq flag. Can reduce metric gather times.
+  dns_lookup = true
+```
+
+### Measurements & Fields:
+
+- ntpq
+    - delay (float, milliseconds)
+    - jitter (float, milliseconds)
+    - offset (float, milliseconds)
+    - poll (int, seconds)
+    - reach (int)
+    - when (int, seconds)
+
+### Tags:
+
+- All measurements have the following tags:
+    - refid
+    - remote
+    - type
+    - stratum
+
+### Example Output:
+
+```
+$ telegraf -config ~/ws/telegraf.conf -input-filter ntpq -test
+* Plugin: ntpq, Collection 1
+> ntpq,refid=.GPSs.,remote=*time.apple.com,stratum=1,type=u delay=91.797,jitter=3.735,offset=12.841,poll=64i,reach=377i,when=35i 1457960478909556134
+```

plugins/inputs/ntpq/ntpq.go

@@ -0,0 +1,192 @@
+// +build !windows
+
+package ntpq
+
+import (
+	"bufio"
+	"bytes"
+	"log"
+	"os/exec"
+	"strconv"
+	"strings"
+
+	"github.com/influxdata/telegraf"
+	"github.com/influxdata/telegraf/plugins/inputs"
+)
+
+// Mapping of ntpq header names to tag keys
+var tagHeaders map[string]string = map[string]string{
+	"remote": "remote",
+	"refid":  "refid",
+	"st":     "stratum",
+	"t":      "type",
+}
+
+// Mapping of the ntpq tag key to the index in the command output
+var tagI map[string]int = map[string]int{
+	"remote":  -1,
+	"refid":   -1,
+	"stratum": -1,
+	"type":    -1,
+}
+
+// Mapping of float metrics to their index in the command output
+var floatI map[string]int = map[string]int{
+	"delay":  -1,
+	"offset": -1,
+	"jitter": -1,
+}
+
+// Mapping of int metrics to their index in the command output
+var intI map[string]int = map[string]int{
+	"when":  -1,
+	"poll":  -1,
+	"reach": -1,
+}
+
+type NTPQ struct {
+	runQ func() ([]byte, error)
+
+	DNSLookup bool `toml:"dns_lookup"`
+}
+
+func (n *NTPQ) Description() string {
+	return "Get standard NTP query metrics, requires ntpq executable."
+}
+
+func (n *NTPQ) SampleConfig() string {
+	return `
+  ## If false, set the -n ntpq flag. Can reduce metric gather times.
+  dns_lookup = true
+`
+}
+
+func (n *NTPQ) Gather(acc telegraf.Accumulator) error {
+	out, err := n.runQ()
+	if err != nil {
+		return err
+	}
+
+	lineCounter := 0
+	scanner := bufio.NewScanner(bytes.NewReader(out))
+	for scanner.Scan() {
+		fields := strings.Fields(scanner.Text())
+		if len(fields) < 2 {
+			continue
+		}
+
+		// If lineCounter == 0, then this is the header line
+		if lineCounter == 0 {
+			for i, field := range fields {
+				// Check if field is a tag:
+				if tagKey, ok := tagHeaders[field]; ok {
+					tagI[tagKey] = i
+					continue
+				}
+
+				// check if field is a float metric:
+				if _, ok := floatI[field]; ok {
+					floatI[field] = i
+					continue
+				}
+
+				// check if field is an int metric:
+				if _, ok := intI[field]; ok {
+					intI[field] = i
+					continue
+				}
+			}
+		} else {
+			tags := make(map[string]string)
+			mFields := make(map[string]interface{})
+
+			// Get tags from output
+			for key, index := range tagI {
+				if index == -1 {
+					continue
+				}
+				tags[key] = fields[index]
+			}
+
+			// Get integer metrics from output
+			for key, index := range intI {
+				if index == -1 {
+					continue
+				}
+
+				if key == "when" {
+					when := fields[index]
+					switch {
+					case strings.HasSuffix(when, "h"):
+						m, err := strconv.Atoi(strings.TrimSuffix(fields[index], "h"))
+						if err != nil {
+							log.Printf("ERROR ntpq: parsing int: %s", fields[index])
+							continue
+						}
+						// seconds in an hour
+						mFields[key] = int64(m) * 360
+						continue
+					case strings.HasSuffix(when, "d"):
+						m, err := strconv.Atoi(strings.TrimSuffix(fields[index], "d"))
+						if err != nil {
+							log.Printf("ERROR ntpq: parsing int: %s", fields[index])
+							continue
+						}
+						// seconds in a day
+						mFields[key] = int64(m) * 86400
+						continue
+					}
+				}
+
+				m, err := strconv.Atoi(fields[index])
+				if err != nil {
+					log.Printf("ERROR ntpq: parsing int: %s", fields[index])
+					continue
+				}
+				mFields[key] = int64(m)
+			}
+
+			// get float metrics from output
+			for key, index := range floatI {
+				if index == -1 {
+					continue
+				}
+
+				m, err := strconv.ParseFloat(fields[index], 64)
+				if err != nil {
+					log.Printf("ERROR ntpq: parsing float: %s", fields[index])
+				}
+				mFields[key] = m
+			}
+
+			acc.AddFields("ntpq", mFields, tags)
+		}
+
+		lineCounter++
+	}
+	return nil
+}
+
+func (n *NTPQ) runq() ([]byte, error) {
+	bin, err := exec.LookPath("ntpq")
+	if err != nil {
+		return nil, err
+	}
+
+	var cmd *exec.Cmd
+	if n.DNSLookup {
+		cmd = exec.Command(bin, "-p")
+	} else {
+		cmd = exec.Command(bin, "-p", "-n")
+	}
+
+	return cmd.Output()
+}
+
+func init() {
+	inputs.Add("ntpq", func() telegraf.Input {
+		n := &NTPQ{}
+		n.runQ = n.runq
+		return n
+	})
+}