Add postfix input plugin (#2553)

README.md

@@ -180,6 +180,7 @@ configuration options.
 * [phpfpm](./plugins/inputs/phpfpm)
 * [phusion passenger](./plugins/inputs/passenger)
 * [ping](./plugins/inputs/ping)
+* [postfix](./plugins/inputs/postfix)
 * [postgresql](./plugins/inputs/postgresql)
 * [postgresql_extensible](./plugins/inputs/postgresql_extensible)
 * [powerdns](./plugins/inputs/powerdns)

plugins/inputs/all/all.go

@@ -64,6 +64,7 @@ import (
 	_ "github.com/influxdata/telegraf/plugins/inputs/passenger"
 	_ "github.com/influxdata/telegraf/plugins/inputs/phpfpm"
 	_ "github.com/influxdata/telegraf/plugins/inputs/ping"
+	_ "github.com/influxdata/telegraf/plugins/inputs/postfix"
 	_ "github.com/influxdata/telegraf/plugins/inputs/postgresql"
 	_ "github.com/influxdata/telegraf/plugins/inputs/postgresql_extensible"
 	_ "github.com/influxdata/telegraf/plugins/inputs/powerdns"

plugins/inputs/postfix/README.md

@@ -0,0 +1,36 @@
+# Postfix Input Plugin
+
+The postfix plugin reports metrics on the postfix queues.
+
+For each of the active, hold, incoming, maildrop, and deferred queues (http://www.postfix.org/QSHAPE_README.html#queues), it will report the queue length (number of items), size (bytes used by items), and age (age of oldest item in seconds).
+
+### Configuration
+
+```toml
+[[inputs.postfix]]
+  ## Postfix queue directory. If not provided, telegraf will try to use
+  ## 'postconf -h queue_directory' to determine it.
+  # queue_directory = "/var/spool/postfix"
+```
+
+### Measurements & Fields:
+
+- postfix_queue
+    - length (integer)
+    - size (integer, bytes)
+    - age (integer, seconds)
+
+### Tags:
+
+- postfix_queue
+    - queue
+
+### Example Output
+
+```
+postfix_queue,queue=active length=3,size=12345,age=9
+postfix_queue,queue=hold length=0,size=0,age=0
+postfix_queue,queue=maildrop length=1,size=2000,age=2
+postfix_queue,queue=incoming length=1,size=1020,age=0
+postfix_queue,queue=deferred length=400,size=76543210,age=3600
+```

plugins/inputs/postfix/postfix.go

@@ -0,0 +1,119 @@
+package postfix
+
+import (
+	"fmt"
+	"os"
+	"os/exec"
+	"path"
+	"strings"
+	"time"
+
+	"github.com/influxdata/telegraf"
+	"github.com/influxdata/telegraf/plugins/inputs"
+)
+
+const sampleConfig = `
+  ## Postfix queue directory. If not provided, telegraf will try to use
+  ## 'postconf -h queue_directory' to determine it.
+  # queue_directory = "/var/spool/postfix"
+`
+
+const description = "Measure postfix queue statistics"
+
+func getQueueDirectory() (string, error) {
+	qd, err := exec.Command("postconf", "-h", "queue_directory").Output()
+	if err != nil {
+		return "", err
+	}
+	return strings.TrimSpace(string(qd)), nil
+}
+
+func qScan(path string) (int64, int64, int64, error) {
+	f, err := os.Open(path)
+	if err != nil {
+		return 0, 0, 0, err
+	}
+
+	finfos, err := f.Readdir(-1)
+	f.Close()
+	if err != nil {
+		return 0, 0, 0, err
+	}
+
+	var length, size int64
+	var oldest time.Time
+	for _, finfo := range finfos {
+		length++
+		size += finfo.Size()
+		if oldest.IsZero() || finfo.ModTime().Before(oldest) {
+			oldest = finfo.ModTime()
+		}
+	}
+	var age time.Duration
+	if !oldest.IsZero() {
+		age = time.Now().Sub(oldest) / time.Second
+	}
+	return length, size, int64(age), nil
+}
+
+type Postfix struct {
+	QueueDirectory string
+}
+
+func (p *Postfix) Gather(acc telegraf.Accumulator) error {
+	if p.QueueDirectory == "" {
+		var err error
+		p.QueueDirectory, err = getQueueDirectory()
+		if err != nil {
+			return fmt.Errorf("unable to determine queue directory: %s", err)
+		}
+	}
+
+	for _, q := range []string{"active", "hold", "incoming", "maildrop"} {
+		length, size, age, err := qScan(path.Join(p.QueueDirectory, q))
+		if err != nil {
+			acc.AddError(fmt.Errorf("error scanning queue %s: %s", q, err))
+			continue
+		}
+		fields := map[string]interface{}{"length": length, "size": size, "age": age}
+		acc.AddFields("postfix_queue", fields, map[string]string{"queue": q})
+	}
+
+	var dLength, dSize, dAge int64
+	for _, q := range []string{"0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "A", "B", "C", "D", "E", "F"} {
+		length, size, age, err := qScan(path.Join(p.QueueDirectory, "deferred", q))
+		if err != nil {
+			if os.IsNotExist(err) {
+				// the directories are created on first use
+				continue
+			}
+			acc.AddError(fmt.Errorf("error scanning queue deferred/%s: %s", q, err))
+			return nil
+		}
+		dLength += length
+		dSize += size
+		if age > dAge {
+			dAge = age
+		}
+	}
+	fields := map[string]interface{}{"length": dLength, "size": dSize, "age": dAge}
+	acc.AddFields("postfix_queue", fields, map[string]string{"queue": "deferred"})
+
+	return nil
+}
+
+func (p *Postfix) SampleConfig() string {
+	return sampleConfig
+}
+
+func (p *Postfix) Description() string {
+	return description
+}
+
+func init() {
+	inputs.Add("postfix", func() telegraf.Input {
+		return &Postfix{
+			QueueDirectory: "/var/spool/postfix",
+		}
+	})
+}

plugins/inputs/postfix/postfix_test.go

@@ -0,0 +1,63 @@
+package postfix
+
+import (
+	"io/ioutil"
+	"os"
+	"path"
+	"testing"
+	"time"
+
+	"github.com/influxdata/telegraf/testutil"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestGather(t *testing.T) {
+	td, err := ioutil.TempDir("", "")
+	require.NoError(t, err)
+	defer os.RemoveAll(td)
+
+	for _, q := range []string{"active", "hold", "incoming", "maildrop", "deferred"} {
+		require.NoError(t, os.Mkdir(path.Join(td, q), 0755))
+	}
+	for _, q := range []string{"0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "A", "B", "C", "D", "F"} { // "E" deliberately left off
+		require.NoError(t, os.Mkdir(path.Join(td, "deferred", q), 0755))
+	}
+
+	require.NoError(t, ioutil.WriteFile(path.Join(td, "active", "01"), []byte("abc"), 0644))
+	require.NoError(t, ioutil.WriteFile(path.Join(td, "active", "02"), []byte("defg"), 0644))
+	require.NoError(t, os.Chtimes(path.Join(td, "active", "02"), time.Now(), time.Now().Add(-time.Hour)))
+	require.NoError(t, ioutil.WriteFile(path.Join(td, "hold", "01"), []byte("abc"), 0644))
+	require.NoError(t, ioutil.WriteFile(path.Join(td, "incoming", "01"), []byte("abcd"), 0644))
+	require.NoError(t, ioutil.WriteFile(path.Join(td, "deferred", "0", "01"), []byte("abc"), 0644))
+	require.NoError(t, ioutil.WriteFile(path.Join(td, "deferred", "F", "F1"), []byte("abc"), 0644))
+
+	p := Postfix{
+		QueueDirectory: td,
+	}
+
+	var acc testutil.Accumulator
+	require.NoError(t, p.Gather(&acc))
+
+	metrics := map[string]*testutil.Metric{}
+	for _, m := range acc.Metrics {
+		metrics[m.Tags["queue"]] = m
+	}
+
+	assert.Equal(t, int64(2), metrics["active"].Fields["length"])
+	assert.Equal(t, int64(7), metrics["active"].Fields["size"])
+	assert.InDelta(t, int64(time.Hour/time.Second), metrics["active"].Fields["age"], 10)
+
+	assert.Equal(t, int64(1), metrics["hold"].Fields["length"])
+	assert.Equal(t, int64(3), metrics["hold"].Fields["size"])
+
+	assert.Equal(t, int64(1), metrics["incoming"].Fields["length"])
+	assert.Equal(t, int64(4), metrics["incoming"].Fields["size"])
+
+	assert.Equal(t, int64(0), metrics["maildrop"].Fields["length"])
+	assert.Equal(t, int64(0), metrics["maildrop"].Fields["size"])
+	assert.Equal(t, int64(0), metrics["maildrop"].Fields["age"])
+
+	assert.Equal(t, int64(2), metrics["deferred"].Fields["length"])
+	assert.Equal(t, int64(6), metrics["deferred"].Fields["size"])
+}