feat(exec, execd): add an option to pass a custom environment to their child process

internal/process/process.go

@@ -5,6 +5,7 @@ import (
 	"errors"
 	"fmt"
 	"io"
+	"os"
 	"os/exec"
 	"sync"
 	"sync/atomic"
@@ -26,13 +27,14 @@ type Process struct {
 
 	name       string
 	args       []string
+	envs       []string
 	pid        int32
 	cancel     context.CancelFunc
 	mainLoopWg sync.WaitGroup
 }
 
 // New creates a new process wrapper
-func New(command []string) (*Process, error) {
+func New(command []string, envs []string) (*Process, error) {
 	if len(command) == 0 {
 		return nil, errors.New("no command")
 	}
@@ -41,6 +43,7 @@ func New(command []string) (*Process, error) {
 		RestartDelay: 5 * time.Second,
 		name:         command[0],
 		args:         []string{},
+		envs:         envs,
 	}
 
 	if len(command) > 1 {
@@ -85,6 +88,10 @@ func (p *Process) Stop() {
 func (p *Process) cmdStart() error {
 	p.Cmd = exec.Command(p.name, p.args...)
 
+	if len(p.envs) > 0 {
+		p.Cmd.Env = append(os.Environ(), p.envs...)
+	}
+
 	var err error
 	p.Stdin, err = p.Cmd.StdinPipe()
 	if err != nil {

internal/process/process_test.go

@@ -27,7 +27,7 @@ func TestRestartingRebindsPipes(t *testing.T) {
 	exe, err := os.Executable()
 	require.NoError(t, err)
 
-	p, err := New([]string{exe, "-external"})
+	p, err := New([]string{exe, "-external"}, []string{"INTERNAL_PROCESS_MODE=application"})
 	p.RestartDelay = 100 * time.Nanosecond
 	p.Log = testutil.Logger{}
 	require.NoError(t, err)
@@ -62,7 +62,8 @@ var external = flag.Bool("external", false,
 
 func TestMain(m *testing.M) {
 	flag.Parse()
-	if *external {
+	runMode := os.Getenv("INTERNAL_PROCESS_MODE")
+	if *external && runMode == "application" {
 		externalProcess()
 		os.Exit(0)
 	}

plugins/inputs/exec/README.md

@@ -17,6 +17,12 @@ This plugin can be used to poll for custom metrics from any source.
     "/tmp/collect_*.sh"
   ]
 
+  ## Environment variables
+  ## Array of "key=value" pairs to pass as environment variables
+  ## e.g. "KEY=value", "USERNAME=John Doe",
+  ## "LD_LIBRARY_PATH=/opt/custom/lib64:/usr/local/libs"
+  # environment = []
+
   ## Timeout for each command to complete.
   timeout = "5s"
 
@@ -55,7 +61,7 @@ It can be paired with the following configuration and will be run at the `interv
 
 ### My script works when I run it by hand, but not when Telegraf is running as a service
 
-This may be related to the Telegraf service running as a different user.  The
+This may be related to the Telegraf service running as a different user. The
 official packages run Telegraf as the `telegraf` user and group on Linux
 systems.
 

plugins/inputs/exec/exec.go

@@ -4,6 +4,7 @@ import (
 	"bytes"
 	"fmt"
 	"io"
+	"os"
 	osExec "os/exec"
 	"path/filepath"
 	"runtime"
@@ -24,9 +25,10 @@ import (
 const MaxStderrBytes int = 512
 
 type Exec struct {
-	Commands []string        `toml:"commands"`
-	Command  string          `toml:"command"`
-	Timeout  config.Duration `toml:"timeout"`
+	Commands    []string        `toml:"commands"`
+	Command     string          `toml:"command"`
+	Environment []string        `toml:"environment"`
+	Timeout     config.Duration `toml:"timeout"`
 
 	parser parsers.Parser
 
@@ -42,13 +44,14 @@ func NewExec() *Exec {
 }
 
 type Runner interface {
-	Run(string, time.Duration) ([]byte, []byte, error)
+	Run(string, []string, time.Duration) ([]byte, []byte, error)
 }
 
 type CommandRunner struct{}
 
 func (c CommandRunner) Run(
 	command string,
+	environments []string,
 	timeout time.Duration,
 ) ([]byte, []byte, error) {
 	splitCmd, err := shellquote.Split(command)
@@ -58,6 +61,10 @@ func (c CommandRunner) Run(
 
 	cmd := osExec.Command(splitCmd[0], splitCmd[1:]...)
 
+	if len(environments) > 0 {
+		cmd.Env = append(os.Environ(), environments...)
+	}
+
 	var (
 		out    bytes.Buffer
 		stderr bytes.Buffer
@@ -120,7 +127,7 @@ func (e *Exec) ProcessCommand(command string, acc telegraf.Accumulator, wg *sync
 	defer wg.Done()
 	_, isNagios := e.parser.(*nagios.NagiosParser)
 
-	out, errbuf, runErr := e.runner.Run(command, time.Duration(e.Timeout))
+	out, errbuf, runErr := e.runner.Run(command, e.Environment, time.Duration(e.Timeout))
 	if !isNagios && runErr != nil {
 		err := fmt.Errorf("exec: %s for command '%s': %s", runErr, command, string(errbuf))
 		acc.AddError(err)

plugins/inputs/exec/exec_test.go

@@ -75,7 +75,7 @@ func newRunnerMock(out []byte, errout []byte, err error) Runner {
 	}
 }
 
-func (r runnerMock) Run(_ string, _ time.Duration) ([]byte, []byte, error) {
+func (r runnerMock) Run(_ string, _ []string, _ time.Duration) ([]byte, []byte, error) {
 	return r.out, r.errout, r.err
 }
 
@@ -191,6 +191,23 @@ func TestExecCommandWithoutGlobAndPath(t *testing.T) {
 	acc.AssertContainsFields(t, "metric", fields)
 }
 
+func TestExecCommandWithEnv(t *testing.T) {
+	parser, _ := parsers.NewValueParser("metric", "string", "", nil)
+	e := NewExec()
+	e.Commands = []string{"/bin/sh -c 'echo ${METRIC_NAME}'"}
+	e.Environment = []string{"METRIC_NAME=metric_value"}
+	e.SetParser(parser)
+
+	var acc testutil.Accumulator
+	err := acc.GatherError(e.Gather)
+	require.NoError(t, err)
+
+	fields := map[string]interface{}{
+		"value": "metric_value",
+	}
+	acc.AssertContainsFields(t, "metric", fields)
+}
+
 func TestTruncate(t *testing.T) {
 	tests := []struct {
 		name string

plugins/inputs/execd/README.md

@@ -22,6 +22,12 @@ STDERR from the process will be relayed to Telegraf as errors in the logs.
   ## NOTE: process and each argument should each be their own string
   command = ["telegraf-smartctl", "-d", "/dev/sda"]
 
+  ## Environment variables
+  ## Array of "key=value" pairs to pass as environment variables
+  ## e.g. "KEY=value", "USERNAME=John Doe",
+  ## "LD_LIBRARY_PATH=/opt/custom/lib64:/usr/local/libs"
+  # environment = []
+
   ## Define how the process is signaled on each collection interval.
   ## Valid values are:
   ##   "none"    : Do not signal anything. (Recommended for service inputs)

plugins/inputs/execd/execd.go

@@ -19,6 +19,7 @@ import (
 
 type Execd struct {
 	Command      []string        `toml:"command"`
+	Environment  []string        `toml:"environment"`
 	Signal       string          `toml:"signal"`
 	RestartDelay config.Duration `toml:"restart_delay"`
 	Log          telegraf.Logger `toml:"-"`
@@ -35,7 +36,7 @@ func (e *Execd) SetParser(parser parsers.Parser) {
 func (e *Execd) Start(acc telegraf.Accumulator) error {
 	e.acc = acc
 	var err error
-	e.process, err = process.New(e.Command)
+	e.process, err = process.New(e.Command, e.Environment)
 	if err != nil {
 		return fmt.Errorf("error creating new process: %w", err)
 	}

plugins/inputs/execd/execd_test.go

@@ -25,6 +25,7 @@ func TestSettingConfigWorks(t *testing.T) {
 	cfg := `
 	[[inputs.execd]]
 		command = ["a", "b", "c"]
+		environment = ["d=e", "f=1"]
 		restart_delay = "1m"
 		signal = "SIGHUP"
 	`
@@ -35,6 +36,7 @@ func TestSettingConfigWorks(t *testing.T) {
 	inp, ok := conf.Inputs[0].Input.(*Execd)
 	require.True(t, ok)
 	require.EqualValues(t, []string{"a", "b", "c"}, inp.Command)
+	require.EqualValues(t, []string{"d=e", "f=1"}, inp.Environment)
 	require.EqualValues(t, 1*time.Minute, inp.RestartDelay)
 	require.EqualValues(t, "SIGHUP", inp.Signal)
 }
@@ -48,6 +50,7 @@ func TestExternalInputWorks(t *testing.T) {
 
 	e := &Execd{
 		Command:      []string{exe, "-counter"},
+		Environment:  []string{"PLUGINS_INPUTS_EXECD_MODE=application", "METRIC_NAME=counter"},
 		RestartDelay: config.Duration(5 * time.Second),
 		parser:       influxParser,
 		Signal:       "STDIN",
@@ -152,7 +155,8 @@ var counter = flag.Bool("counter", false,
 
 func TestMain(m *testing.M) {
 	flag.Parse()
-	if *counter {
+	runMode := os.Getenv("PLUGINS_INPUTS_EXECD_MODE")
+	if *counter && runMode == "application" {
 		if err := runCounterProgram(); err != nil {
 			os.Exit(1)
 		}
@@ -163,6 +167,7 @@ func TestMain(m *testing.M) {
 }
 
 func runCounterProgram() error {
+	envMetricName := os.Getenv("METRIC_NAME")
 	i := 0
 	serializer, err := serializers.NewInfluxSerializer()
 	if err != nil {
@@ -173,7 +178,7 @@ func runCounterProgram() error {
 
 	scanner := bufio.NewScanner(os.Stdin)
 	for scanner.Scan() {
-		m := metric.New("counter",
+		m := metric.New(envMetricName,
 			map[string]string{},
 			map[string]interface{}{
 				"count": i,

plugins/outputs/exec/README.md

@@ -20,6 +20,12 @@ For better performance, consider execd, which runs continuously.
   ## Command to ingest metrics via stdin.
   command = ["tee", "-a", "/dev/null"]
 
+  ## Environment variables
+  ## Array of "key=value" pairs to pass as environment variables
+  ## e.g. "KEY=value", "USERNAME=John Doe",
+  ## "LD_LIBRARY_PATH=/opt/custom/lib64:/usr/local/libs"
+  # environment = []
+
   ## Timeout for command to complete.
   # timeout = "5s"
 

plugins/outputs/exec/exec.go

@@ -4,6 +4,7 @@ import (
 	"bytes"
 	"fmt"
 	"io"
+	"os"
 	"os/exec"
 	"runtime"
 	"time"
@@ -19,9 +20,10 @@ const maxStderrBytes = 512
 
 // Exec defines the exec output plugin.
 type Exec struct {
-	Command []string        `toml:"command"`
-	Timeout config.Duration `toml:"timeout"`
-	Log     telegraf.Logger `toml:"-"`
+	Command     []string        `toml:"command"`
+	Environment []string        `toml:"environment"`
+	Timeout     config.Duration `toml:"timeout"`
+	Log         telegraf.Logger `toml:"-"`
 
 	runner     Runner
 	serializer serializers.Serializer
@@ -61,12 +63,12 @@ func (e *Exec) Write(metrics []telegraf.Metric) error {
 		return nil
 	}
 
-	return e.runner.Run(time.Duration(e.Timeout), e.Command, &buffer)
+	return e.runner.Run(time.Duration(e.Timeout), e.Command, e.Environment, &buffer)
 }
 
 // Runner provides an interface for running exec.Cmd.
 type Runner interface {
-	Run(time.Duration, []string, io.Reader) error
+	Run(time.Duration, []string, []string, io.Reader) error
 }
 
 // CommandRunner runs a command with the ability to kill the process before the timeout.
@@ -76,8 +78,11 @@ type CommandRunner struct {
 }
 
 // Run runs the command.
-func (c *CommandRunner) Run(timeout time.Duration, command []string, buffer io.Reader) error {
+func (c *CommandRunner) Run(timeout time.Duration, command []string, environments []string, buffer io.Reader) error {
 	cmd := exec.Command(command[0], command[1:]...)
+	if len(environments) > 0 {
+		cmd.Env = append(os.Environ(), environments...)
+	}
 	cmd.Stdin = buffer
 	var stderr bytes.Buffer
 	cmd.Stderr = &stderr

plugins/outputs/execd/README.md

@@ -13,6 +13,12 @@ Telegraf minimum version: Telegraf 1.15.0
   ## NOTE: process and each argument should each be their own string
   command = ["my-telegraf-output", "--some-flag", "value"]
 
+  ## Environment variables
+  ## Array of "key=value" pairs to pass as environment variables
+  ## e.g. "KEY=value", "USERNAME=John Doe",
+  ## "LD_LIBRARY_PATH=/opt/custom/lib64:/usr/local/libs"
+  # environment = []
+
   ## Delay before the process is restarted after an unexpected termination
   restart_delay = "10s"
 

plugins/outputs/execd/execd.go

@@ -16,6 +16,7 @@ import (
 
 type Execd struct {
 	Command      []string        `toml:"command"`
+	Environment  []string        `toml:"environment"`
 	RestartDelay config.Duration `toml:"restart_delay"`
 	Log          telegraf.Logger
 
@@ -34,7 +35,7 @@ func (e *Execd) Init() error {
 
 	var err error
 
-	e.process, err = process.New(e.Command)
+	e.process, err = process.New(e.Command, e.Environment)
 	if err != nil {
 		return fmt.Errorf("error creating process %s: %w", e.Command, err)
 	}

plugins/outputs/execd/execd_test.go

@@ -32,6 +32,7 @@ func TestExternalOutputWorks(t *testing.T) {
 
 	e := &Execd{
 		Command:      []string{exe, "-testoutput"},
+		Environment:  []string{"PLUGINS_OUTPUTS_EXECD_MODE=application", "METRIC_NAME=cpu"},
 		RestartDelay: config.Duration(5 * time.Second),
 		serializer:   influxSerializer,
 		Log:          testutil.Logger{},
@@ -74,7 +75,8 @@ var testoutput = flag.Bool("testoutput", false,
 
 func TestMain(m *testing.M) {
 	flag.Parse()
-	if *testoutput {
+	runMode := os.Getenv("PLUGINS_OUTPUTS_EXECD_MODE")
+	if *testoutput && runMode == "application" {
 		runOutputConsumerProgram()
 		os.Exit(0)
 	}
@@ -83,6 +85,7 @@ func TestMain(m *testing.M) {
 }
 
 func runOutputConsumerProgram() {
+	metricName := os.Getenv("METRIC_NAME")
 	parser := influx.NewStreamParser(os.Stdin)
 
 	for {
@@ -103,7 +106,7 @@ func runOutputConsumerProgram() {
 			os.Exit(1)
 		}
 
-		expected := testutil.MustMetric("cpu",
+		expected := testutil.MustMetric(metricName,
 			map[string]string{"name": "cpu1"},
 			map[string]interface{}{"idle": 50, "sys": 30},
 			now,

plugins/processors/execd/README.md

@@ -30,6 +30,12 @@ Telegraf minimum version: Telegraf 1.15.0
   ## eg: command = ["/path/to/your_program", "arg1", "arg2"]
   command = ["cat"]
 
+  ## Environment variables
+  ## Array of "key=value" pairs to pass as environment variables
+  ## e.g. "KEY=value", "USERNAME=John Doe",
+  ## "LD_LIBRARY_PATH=/opt/custom/lib64:/usr/local/libs"
+  # environment = []
+
   ## Delay before the process is restarted after an unexpected termination
   # restart_delay = "10s"
 ```