Add exec plugin

plugins/all/all.go

@@ -3,6 +3,7 @@ package all
 import (
 	_ "github.com/influxdb/telegraf/plugins/disque"
 	_ "github.com/influxdb/telegraf/plugins/elasticsearch"
+	_ "github.com/influxdb/telegraf/plugins/exec"
 	_ "github.com/influxdb/telegraf/plugins/haproxy"
 	_ "github.com/influxdb/telegraf/plugins/kafka_consumer"
 	_ "github.com/influxdb/telegraf/plugins/lustre2"

plugins/exec/exec.go

@@ -0,0 +1,125 @@
+package exec
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"github.com/gonuts/go-shellquote"
+	"github.com/influxdb/telegraf/plugins"
+	"os/exec"
+	"sync"
+)
+
+const sampleConfig = `
+# specify commands via an array of tables
+[[exec.commands]]
+# the command to run
+command = "/usr/bin/mycollector --foo=bar"
+
+# name of the command (used as a prefix for measurements)
+name = "mycollector"
+`
+
+type Command struct {
+	Command string
+	Name    string
+}
+
+type Exec struct {
+	Commands []*Command
+	runner   Runner
+}
+
+type Runner interface {
+	Run(string, ...string) ([]byte, error)
+}
+
+type CommandRunner struct {
+}
+
+func NewExec() *Exec {
+	return &Exec{runner: CommandRunner{}}
+}
+
+func (c CommandRunner) Run(command string, args ...string) ([]byte, error) {
+	cmd := exec.Command(command, args...)
+	var out bytes.Buffer
+	cmd.Stdout = &out
+
+	if err := cmd.Run(); err != nil {
+		return nil, fmt.Errorf("exec: %s for command '%s'", err, command)
+	}
+
+	return out.Bytes(), nil
+}
+
+func (e *Exec) SampleConfig() string {
+	return sampleConfig
+}
+
+func (e *Exec) Description() string {
+	return "Read flattened metrics from one or more commands that output JSON to stdout"
+}
+
+func (e *Exec) Gather(acc plugins.Accumulator) error {
+	var wg sync.WaitGroup
+
+	var outerr error
+
+	for _, c := range e.Commands {
+		wg.Add(1)
+		go func(c *Command, acc plugins.Accumulator) {
+			defer wg.Done()
+			outerr = e.gatherCommand(c, acc)
+		}(c, acc)
+	}
+
+	wg.Wait()
+
+	return outerr
+}
+
+func (e *Exec) gatherCommand(c *Command, acc plugins.Accumulator) error {
+	words, err := shellquote.Split(c.Command)
+	if err != nil || len(words) == 0 {
+		return fmt.Errorf("exec: unable to parse command, %s", err)
+	}
+
+	out, err := e.runner.Run(words[0], words[1:]...)
+	if err != nil {
+		return err
+	}
+
+	var jsonOut interface{}
+	err = json.Unmarshal(out, &jsonOut)
+	if err != nil {
+		return fmt.Errorf("exec: unable to parse output of '%s' as JSON, %s", c.Command, err)
+	}
+
+	return processResponse(acc, c.Name, map[string]string{}, jsonOut)
+}
+
+func processResponse(acc plugins.Accumulator, prefix string, tags map[string]string, v interface{}) error {
+	switch t := v.(type) {
+	case map[string]interface{}:
+		for k, v := range t {
+			if err := processResponse(acc, prefix+"_"+k, tags, v); err != nil {
+				return err
+			}
+		}
+	case float64:
+		acc.Add(prefix, v, tags)
+	case bool, string, []interface{}:
+		// ignored types
+		return nil
+	default:
+		return fmt.Errorf("exec: got unexpected type %T with value %v (%s)", t, v, prefix)
+	}
+	return nil
+}
+
+func init() {
+	plugins.Add("exec", func() plugins.Plugin {
+		return NewExec()
+	})
+}

plugins/exec/exec_test.go

@@ -0,0 +1,88 @@
+package exec
+
+import (
+	"fmt"
+	"github.com/influxdb/telegraf/testutil"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	"testing"
+)
+
+const validJson = `
+{
+    "status": "green",
+    "num_processes": 82,
+    "cpu": {
+        "status": "red",
+        "used": 8234,
+        "free": 32
+    },
+    "percent": 0.81,
+    "users": [0, 1, 2, 3]
+}`
+
+const malformedJson = `
+{
+    "status": "green",
+`
+
+type runnerMock struct {
+	out []byte
+	err error
+}
+
+func newRunnerMock(out []byte, err error) Runner {
+	return &runnerMock{out: out, err: err}
+}
+
+func (r runnerMock) Run(command string, args ...string) ([]byte, error) {
+	if r.err != nil {
+		return nil, r.err
+	}
+	return r.out, nil
+}
+
+func TestExec(t *testing.T) {
+	runner := newRunnerMock([]byte(validJson), nil)
+	command := Command{Command: "testcommand arg1", Name: "mycollector"}
+	e := &Exec{runner: runner, Commands: []*Command{&command}}
+
+	var acc testutil.Accumulator
+	err := e.Gather(&acc)
+	require.NoError(t, err)
+
+	checkFloat := []struct {
+		name  string
+		value float64
+	}{
+		{"mycollector_num_processes", 82},
+		{"mycollector_cpu_used", 8234},
+		{"mycollector_cpu_free", 32},
+		{"mycollector_percent", 0.81},
+	}
+
+	for _, c := range checkFloat {
+		assert.True(t, acc.CheckValue(c.name, c.value))
+	}
+
+	assert.Equal(t, len(acc.Points), 4, "non-numeric measurements should be ignored")
+}
+
+func TestExecMalformed(t *testing.T) {
+	runner := newRunnerMock([]byte(malformedJson), nil)
+	command := Command{Command: "badcommand arg1", Name: "mycollector"}
+	e := &Exec{runner: runner, Commands: []*Command{&command}}
+
+	var acc testutil.Accumulator
+	err := e.Gather(&acc)
+	require.Error(t, err)
+}
+
+func TestCommandError(t *testing.T) {
+	runner := newRunnerMock(nil, fmt.Errorf("exit status code 1"))
+	command := Command{Command: "badcommand", Name: "mycollector"}
+	e := &Exec{runner: runner, Commands: []*Command{&command}}
+	var acc testutil.Accumulator
+	err := e.Gather(&acc)
+	require.Error(t, err)
+}