add chrony support (#1238)

* add chrony support

* remove path definition

* add changelog

plugins/inputs/chrony/chrony_test.go

@@ -0,0 +1,95 @@
+// +build linux
+
+package chrony
+
+import (
+	"fmt"
+	"os"
+	"os/exec"
+	"testing"
+
+	"github.com/influxdata/telegraf/testutil"
+)
+
+func TestGather(t *testing.T) {
+	c := Chrony{
+		path: "chronyc",
+	}
+	// overwriting exec commands with mock commands
+	execCommand = fakeExecCommand
+	defer func() { execCommand = exec.Command }()
+	var acc testutil.Accumulator
+
+	err := c.Gather(&acc)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	tags := map[string]string{
+		"reference_id": "192.168.1.22",
+		"leap_status":  "normal",
+		"stratum":      "3",
+	}
+	fields := map[string]interface{}{
+		"last_offset":     0.000012651,
+		"rms_offset":      0.000025577,
+		"frequency":       -16.001,
+		"residual_freq":   0.0,
+		"skew":            0.006,
+		"root_delay":      0.001655,
+		"root_dispersion": 0.003307,
+		"update_interval": 507.2,
+	}
+
+	acc.AssertContainsTaggedFields(t, "chrony", fields, tags)
+}
+
+// fackeExecCommand is a helper function that mock
+// the exec.Command call (and call the test binary)
+func fakeExecCommand(command string, args ...string) *exec.Cmd {
+	cs := []string{"-test.run=TestHelperProcess", "--", command}
+	cs = append(cs, args...)
+	cmd := exec.Command(os.Args[0], cs...)
+	cmd.Env = []string{"GO_WANT_HELPER_PROCESS=1"}
+	return cmd
+}
+
+// TestHelperProcess isn't a real test. It's used to mock exec.Command
+// For example, if you run:
+// GO_WANT_HELPER_PROCESS=1 go test -test.run=TestHelperProcess -- chrony tracking
+// it returns below mockData.
+func TestHelperProcess(t *testing.T) {
+	if os.Getenv("GO_WANT_HELPER_PROCESS") != "1" {
+		return
+	}
+
+	mockData := `Reference ID    : 192.168.1.22 (ntp.example.com)
+Stratum         : 3
+Ref time (UTC)  : Thu May 12 14:27:07 2016
+System time     : 0.000020390 seconds fast of NTP time
+Last offset     : +0.000012651 seconds
+RMS offset      : 0.000025577 seconds
+Frequency       : 16.001 ppm slow
+Residual freq   : -0.000 ppm
+Skew            : 0.006 ppm
+Root delay      : 0.001655 seconds
+Root dispersion : 0.003307 seconds
+Update interval : 507.2 seconds
+Leap status     : Normal
+`
+
+	args := os.Args
+
+	// Previous arguments are tests stuff, that looks like :
+	// /tmp/go-build970079519/…/_test/integration.test -test.run=TestHelperProcess --
+	cmd, args := args[3], args[4:]
+
+	if cmd == "chronyc" && args[0] == "tracking" {
+		fmt.Fprint(os.Stdout, mockData)
+	} else {
+		fmt.Fprint(os.Stdout, "command not found")
+		os.Exit(1)
+
+	}
+	os.Exit(0)
+}