telegraf/plugins/outputs/exec/exec.go

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2019-08-21 00:07:24 +00:00
package exec
import (
"bytes"
"fmt"
"io"
"log"
"os/exec"
"time"
"github.com/influxdata/telegraf"
"github.com/influxdata/telegraf/internal"
"github.com/influxdata/telegraf/plugins/outputs"
"github.com/influxdata/telegraf/plugins/serializers"
)
const maxStderrBytes = 512
// Exec defines the exec output plugin.
type Exec struct {
Command []string `toml:"command"`
Timeout internal.Duration `toml:"timeout"`
runner Runner
serializer serializers.Serializer
}
var sampleConfig = `
## Command to injest metrics via stdin.
command = ["tee", "-a", "/dev/null"]
## Timeout for command to complete.
# timeout = "5s"
## Data format to output.
## Each data format has its own unique set of configuration options, read
## more about them here:
## https://github.com/influxdata/telegraf/blob/master/docs/DATA_FORMATS_OUTPUT.md
# data_format = "influx"
`
// SetSerializer sets the serializer for the output.
func (e *Exec) SetSerializer(serializer serializers.Serializer) {
e.serializer = serializer
}
// Connect satisfies the Ouput interface.
func (e *Exec) Connect() error {
return nil
}
// Close satisfies the Ouput interface.
func (e *Exec) Close() error {
return nil
}
// Description describes the plugin.
func (e *Exec) Description() string {
return "Send metrics to command as input over stdin"
}
// SampleConfig returns a sample configuration.
func (e *Exec) SampleConfig() string {
return sampleConfig
}
// Write writes the metrics to the configured command.
func (e *Exec) Write(metrics []telegraf.Metric) error {
var buffer bytes.Buffer
serializedMetrics, err := e.serializer.SerializeBatch(metrics)
if err != nil {
return err
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}
buffer.Write(serializedMetrics)
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if buffer.Len() <= 0 {
return nil
}
return e.runner.Run(e.Timeout.Duration, e.Command, &buffer)
}
// Runner provides an interface for running exec.Cmd.
type Runner interface {
Run(time.Duration, []string, io.Reader) error
}
// CommandRunner runs a command with the ability to kill the process before the timeout.
type CommandRunner struct {
cmd *exec.Cmd
}
// Run runs the command.
func (c *CommandRunner) Run(timeout time.Duration, command []string, buffer io.Reader) error {
cmd := exec.Command(command[0], command[1:]...)
cmd.Stdin = buffer
var stderr bytes.Buffer
cmd.Stderr = &stderr
err := internal.RunTimeout(cmd, timeout)
s := stderr
if err != nil {
if err == internal.TimeoutErr {
return fmt.Errorf("%q timed out and was killed", command)
}
if s.Len() > 0 {
log.Printf("E! [outputs.exec] Command error: %q", truncate(s))
}
if status, ok := internal.ExitStatus(err); ok {
return fmt.Errorf("%q exited %d with %s", command, status, err.Error())
}
return fmt.Errorf("%q failed with %s", command, err.Error())
}
c.cmd = cmd
return nil
}
func truncate(buf bytes.Buffer) string {
// Limit the number of bytes.
didTruncate := false
if buf.Len() > maxStderrBytes {
buf.Truncate(maxStderrBytes)
didTruncate = true
}
if i := bytes.IndexByte(buf.Bytes(), '\n'); i > 0 {
// Only show truncation if the newline wasn't the last character.
if i < buf.Len()-1 {
didTruncate = true
}
buf.Truncate(i)
}
if didTruncate {
buf.WriteString("...")
}
return buf.String()
}
func init() {
outputs.Add("exec", func() telegraf.Output {
return &Exec{
runner: &CommandRunner{},
Timeout: internal.Duration{Duration: time.Second * 5},
}
})
}