Memcached plugin

plugins/memcached/memcached.go

@@ -0,0 +1,148 @@
+package memcached
+
+import (
+	"bufio"
+	"bytes"
+	"fmt"
+	"net"
+	"strconv"
+	"time"
+
+	"github.com/influxdb/telegraf/plugins"
+)
+
+// Memcached is a memcached plugin
+type Memcached struct {
+	Servers []string
+}
+
+var sampleConfig = `
+# An array of address to gather stats about. Specify an ip on hostname
+# with optional port. ie localhost, 10.0.0.1:11211, etc.
+#
+# If no servers are specified, then localhost is used as the host.
+servers = ["localhost"]`
+
+var defaultTimeout = 5 * time.Second
+
+// The list of metrics tha should be calculated
+var sendAsIs = []string{
+	"get_hits",
+	"get_misses",
+	"evictions",
+}
+
+// SampleConfig returns sample configuration message
+func (m *Memcached) SampleConfig() string {
+	return sampleConfig
+}
+
+// Description returns description of Memcached plugin
+func (m *Memcached) Description() string {
+	return "Read metrics from one or many memcached servers"
+}
+
+// Gather reads stats from all configured servers accumulates stats
+func (m *Memcached) Gather(acc plugins.Accumulator) error {
+	if len(m.Servers) == 0 {
+		return m.gatherServer(":11211", acc)
+	}
+
+	for _, serverAddress := range m.Servers {
+		if err := m.gatherServer(serverAddress, acc); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+func (m *Memcached) gatherServer(address string, acc plugins.Accumulator) error {
+	_, _, err := net.SplitHostPort(address)
+	if err != nil {
+		address = address + ":11211"
+	}
+
+	// Connect
+	conn, err := net.DialTimeout("tcp", address, defaultTimeout)
+	if err != nil {
+		return err
+	}
+	defer conn.Close()
+
+	// Extend connection
+	conn.SetDeadline(time.Now().Add(defaultTimeout))
+
+	// Read and write buffer
+	rw := bufio.NewReadWriter(bufio.NewReader(conn), bufio.NewWriter(conn))
+
+	// Send command
+	if _, err = fmt.Fprint(rw, "stats\r\n"); err != nil {
+		return err
+	}
+	if err = rw.Flush(); err != nil {
+		return err
+	}
+
+	// Read response
+	values := make(map[string]string)
+
+	for {
+		// Read line
+		line, _, errRead := rw.Reader.ReadLine()
+		if errRead != nil {
+			return errRead
+		}
+		// Done
+		if bytes.Equal(line, []byte("END")) {
+			break
+		}
+		// Read values
+		var name, value string
+		n, errScan := fmt.Sscanf(string(line), "STAT %s %s\r\n", &name, &value)
+		if errScan != nil || n != 2 {
+			return fmt.Errorf("unexpected line in stats response: %q", line)
+		}
+
+		// Save values
+		values[name] = value
+	}
+
+	//
+	tags := map[string]string{"server": address}
+
+	// Process values
+	for _, key := range sendAsIs {
+		if value, ok := values[key]; ok {
+			// Mostly it is the number
+			if iValue, errParse := strconv.ParseInt(value, 10, 64); errParse != nil {
+				acc.Add(key, value, tags)
+			} else {
+				acc.Add(key, iValue, tags)
+			}
+		}
+	}
+
+	// Usage
+	acc.Add("usage", m.calcUsage(values), tags)
+	return nil
+}
+
+func (m *Memcached) calcUsage(values map[string]string) float64 {
+	maxBytes, maxOk := values["limit_maxbytes"]
+	bytes, bytesOk := values["bytes"]
+	if maxOk && bytesOk {
+		if fMax, errMax := strconv.ParseFloat(maxBytes, 64); errMax == nil && fMax > 0 {
+			if fBytes, errBytes := strconv.ParseFloat(bytes, 64); errBytes == nil {
+				return fBytes / fMax
+			}
+		}
+	}
+	return 0
+}
+
+func init() {
+	plugins.Add("memcached", func() plugins.Plugin {
+		return &Memcached{}
+	})
+}

plugins/memcached/memcached_test.go

@@ -0,0 +1,31 @@
+package memcached
+
+import (
+	"testing"
+
+	"github.com/influxdb/telegraf/testutil"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestMemcachedGeneratesMetrics(t *testing.T) {
+	m := &Memcached{
+		Servers: []string{"localhost"},
+	}
+
+	var acc testutil.Accumulator
+
+	err := m.Gather(&acc)
+	require.NoError(t, err)
+
+	intMetrics := []string{"get_hits", "get_misses", "evictions"}
+	floatMetrics := []string{"usage"}
+
+	for _, metric := range intMetrics {
+		assert.True(t, acc.HasIntValue(metric), metric)
+	}
+
+	for _, metric := range floatMetrics {
+		assert.True(t, acc.HasFloatValue(metric), metric)
+	}
+}