Add opensmtpd input plugin (#3449)

plugins/inputs/opensmtpd/opensmtpd.go

@@ -0,0 +1,134 @@
+package opensmtpd
+
+import (
+	"bufio"
+	"bytes"
+	"fmt"
+	"os/exec"
+	"strconv"
+	"strings"
+	"time"
+
+	"github.com/influxdata/telegraf"
+	"github.com/influxdata/telegraf/filter"
+	"github.com/influxdata/telegraf/internal"
+	"github.com/influxdata/telegraf/plugins/inputs"
+)
+
+type runner func(cmdName string, Timeout internal.Duration, UseSudo bool) (*bytes.Buffer, error)
+
+// Opensmtpd is used to store configuration values
+type Opensmtpd struct {
+	Binary  string
+	Timeout internal.Duration
+	UseSudo bool
+
+	filter filter.Filter
+	run    runner
+}
+
+var defaultBinary = "/usr/sbin/smtpctl"
+var defaultTimeout = internal.Duration{Duration: time.Second}
+
+var sampleConfig = `
+  ## If running as a restricted user you can prepend sudo for additional access:
+  #use_sudo = false
+
+  ## The default location of the smtpctl binary can be overridden with:
+  binary = "/usr/sbin/smtpctl"
+
+  ## The default timeout of 1000ms can be overriden with (in milliseconds):
+  timeout = 1000
+`
+
+func (s *Opensmtpd) Description() string {
+	return "A plugin to collect stats from Opensmtpd - a validating, recursive, and caching DNS resolver "
+}
+
+// SampleConfig displays configuration instructions
+func (s *Opensmtpd) SampleConfig() string {
+	return sampleConfig
+}
+
+// Shell out to opensmtpd_stat and return the output
+func opensmtpdRunner(cmdName string, Timeout internal.Duration, UseSudo bool) (*bytes.Buffer, error) {
+	cmdArgs := []string{"show", "stats"}
+
+	cmd := exec.Command(cmdName, cmdArgs...)
+
+	if UseSudo {
+		cmdArgs = append([]string{cmdName}, cmdArgs...)
+		cmd = exec.Command("sudo", cmdArgs...)
+	}
+
+	var out bytes.Buffer
+	cmd.Stdout = &out
+	err := internal.RunTimeout(cmd, Timeout.Duration)
+	if err != nil {
+		return &out, fmt.Errorf("error running smtpctl: %s", err)
+	}
+
+	return &out, nil
+}
+
+// Gather collects the configured stats from smtpctl and adds them to the
+// Accumulator
+//
+// All the dots in stat name will replaced by underscores. Histogram statistics will not be collected.
+func (s *Opensmtpd) Gather(acc telegraf.Accumulator) error {
+	// Always exclude uptime.human statistics
+	stat_excluded := []string{"uptime.human"}
+	filter_excluded, err := filter.Compile(stat_excluded)
+	if err != nil {
+		return err
+	}
+
+	out, err := s.run(s.Binary, s.Timeout, s.UseSudo)
+	if err != nil {
+		return fmt.Errorf("error gathering metrics: %s", err)
+	}
+
+	// Process values
+	fields := make(map[string]interface{})
+	scanner := bufio.NewScanner(out)
+	for scanner.Scan() {
+
+		cols := strings.Split(scanner.Text(), "=")
+
+		// Check split correctness
+		if len(cols) != 2 {
+			continue
+		}
+
+		stat := cols[0]
+		value := cols[1]
+
+		// Filter value
+		if filter_excluded.Match(stat) {
+			continue
+		}
+
+		field := strings.Replace(stat, ".", "_", -1)
+
+		fields[field], err = strconv.ParseFloat(value, 64)
+		if err != nil {
+			acc.AddError(fmt.Errorf("Expected a numerical value for %s = %v\n",
+				stat, value))
+		}
+	}
+
+	acc.AddFields("opensmtpd", fields, nil)
+
+	return nil
+}
+
+func init() {
+	inputs.Add("opensmtpd", func() telegraf.Input {
+		return &Opensmtpd{
+			run:     opensmtpdRunner,
+			Binary:  defaultBinary,
+			Timeout: defaultTimeout,
+			UseSudo: false,
+		}
+	})
+}