Add ability to query many redis servers

plugins/redis/redis.go

@@ -7,13 +7,15 @@ import (
 	"net"
 	"strconv"
 	"strings"
+	"sync"
 
 	"github.com/influxdb/tivan/plugins"
 )
 
-type Gatherer struct {
+type Redis struct {
 	Disabled bool
 	Address  string
+	Servers  []string
 
 	c   net.Conn
 	buf []byte
@@ -54,13 +56,41 @@ var Tracking = map[string]string{
 
 var ErrProtocolError = errors.New("redis protocol error")
 
-func (g *Gatherer) Gather(acc plugins.Accumulator) error {
+// Reads stats from all configured servers accumulates stats.
-	if g.Address == "" || g.Disabled {
+// Returns one of the errors encountered while gather stats (if any).
+func (g *Redis) Gather(acc plugins.Accumulator) error {
+	if g.Disabled {
 		return nil
 	}
 
+	var wg sync.WaitGroup
+
+	var outerr error
+
+	var servers []string
+
+	if g.Address != "" {
+		servers = append(servers, g.Address)
+	}
+
+	servers = append(servers, g.Servers...)
+
+	for _, serv := range servers {
+		wg.Add(1)
+		go func(serv string) {
+			defer wg.Done()
+			outerr = g.gatherServer(serv, acc)
+		}(serv)
+	}
+
+	wg.Wait()
+
+	return outerr
+}
+
+func (g *Redis) gatherServer(addr string, acc plugins.Accumulator) error {
 	if g.c == nil {
-		c, err := net.Dial("tcp", g.Address)
+		c, err := net.Dial("tcp", addr)
 		if err != nil {
 			return err
 		}
@@ -134,6 +164,6 @@ func (g *Gatherer) Gather(acc plugins.Accumulator) error {
 
 func init() {
 	plugins.Add("redis", func() plugins.Plugin {
-		return &Gatherer{}
+		return &Redis{}
 	})
 }

plugins/redis/redis_test.go

@@ -42,7 +42,7 @@ func TestRedisGeneratesMetrics(t *testing.T) {
 
 	addr := l.Addr().String()
 
-	r := &Gatherer{
+	r := &Redis{
 		Address: addr,
 	}
 
@@ -102,6 +102,97 @@ func TestRedisGeneratesMetrics(t *testing.T) {
 	}
 }
 
+func TestRedisCanPullStatsFromMultipleServers(t *testing.T) {
+	l, err := net.Listen("tcp", ":0")
+	require.NoError(t, err)
+
+	defer l.Close()
+
+	go func() {
+		c, err := l.Accept()
+		if err != nil {
+			return
+		}
+
+		buf := bufio.NewReader(c)
+
+		for {
+			line, err := buf.ReadString('\n')
+			if err != nil {
+				return
+			}
+
+			if line != "info\n" {
+				return
+			}
+
+			fmt.Fprintf(c, "$%d\n", len(testOutput))
+			c.Write([]byte(testOutput))
+		}
+	}()
+
+	addr := l.Addr().String()
+
+	r := &Redis{
+		Servers: []string{addr},
+	}
+
+	var acc testutil.Accumulator
+
+	err = r.Gather(&acc)
+	require.NoError(t, err)
+
+	checkInt := []struct {
+		name  string
+		value uint64
+	}{
+		{"redis_uptime", 238},
+		{"redis_clients", 1},
+		{"redis_used_memory", 1003936},
+		{"redis_used_memory_rss", 811008},
+		{"redis_used_memory_peak", 1003936},
+		{"redis_used_memory_lua", 33792},
+		{"redis_rdb_changes_since_last_save", 0},
+		{"redis_total_connections_received", 2},
+		{"redis_total_commands_processed", 1},
+		{"redis_instantaneous_ops_per_sec", 0},
+		{"redis_sync_full", 0},
+		{"redis_sync_partial_ok", 0},
+		{"redis_sync_partial_err", 0},
+		{"redis_expired_keys", 0},
+		{"redis_evicted_keys", 0},
+		{"redis_keyspace_hits", 0},
+		{"redis_keyspace_misses", 0},
+		{"redis_pubsub_channels", 0},
+		{"redis_pubsub_patterns", 0},
+		{"redis_latest_fork_usec", 0},
+		{"redis_connected_slaves", 0},
+		{"redis_master_repl_offset", 0},
+		{"redis_repl_backlog_active", 0},
+		{"redis_repl_backlog_size", 1048576},
+		{"redis_repl_backlog_histlen", 0},
+	}
+
+	for _, c := range checkInt {
+		assert.NoError(t, acc.ValidateValue(c.name, c.value))
+	}
+
+	checkFloat := []struct {
+		name  string
+		value float64
+	}{
+		{"redis_mem_fragmentation_ratio", 0.81},
+		{"redis_used_cpu_sys", 0.14},
+		{"redis_used_cpu_user", 0.05},
+		{"redis_used_cpu_sys_children", 0.00},
+		{"redis_used_cpu_user_children", 0.00},
+	}
+
+	for _, c := range checkFloat {
+		assert.NoError(t, acc.ValidateValue(c.name, c.value))
+	}
+}
+
 const testOutput = `# Server
 redis_version:2.8.9
 redis_git_sha1:00000000