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 for _, metric := range metrics { value, err := e.serializer.Serialize(metric) if err != nil { return err } buffer.Write(value) } 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}, } }) }